Ferrofluid is an amazing substance if you own a large Direct Drive  hubmotor. It does NOT benefit geared hubs or mid drives, but…if you like the double D’s, you need to read this article.

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Ferrofluid, what is it?

If you own a large Direct Drive  (DD) hubmotor, you will likely find this information interesting and helpful. FF is a liquid with ferrous (iron oxide) particles suspended in it, that bridges the magnetic air-gap between the stator and the rotor in a DD hubmotor, and it allows the heat in the hot stator coils to move to the aluminum side-plates much faster.

Why should you care? The answer is HEAT…the “real” limiting factor in just about every ebike power system component is how much heat it can survive. Forget about what the factories ads rate their components at (the controller, battery, and motor). Some companies purposefully rate them for more  amps of heat than they can ever possibly survive (in order to impress new customers), and other companies purposefully under-rate their components, so that they can avoid as many warranty failure claims as possible.

The actual power limit of controllers, battery packs, and motors is how much HEAT they can survive.

If you live where there are uphills are long and steep,  your hubmotor will just keep getting hotter and hotter all the way up. Hopefully, your motor or controller will not fry before it reaches the top. However…for those ebikers that live on relatively flat land? Large DD hubmotors have been holding on and surviving because they work quite well in that demographic. When a rider applies the full max amps when the light turns green, they are only applying high heat to the motor for a few seconds, and then…during the majority of the cruise-phase, the motor and controller are both cooling off while they are drawing the minimum amps needed to maintain speed.

This is where FF steps in and might even allow you to double the power of your system.

Inside DD hubmotors, there is an air layer between the stator (connected to the axle) and the rotor (connected to the spokes and rim). This air-layer acts as an insulator between the heat of the stator coils and the part of the motor that is connected to the outside air.

I have been a vocal advocate for the hubmotor variations that have a cast aluminum stator support (shown below, on the right side), to act as a heat sponge (instead of the common thin stamped-steel stator support, shown on the left). This single modification allows builders to spec a higher-amp controller, because the aluminum mass will absorb heat-spikes during acceleration, and then to shed it over time.

However, the motors that have this aluminum stator-support still  have to shed their accumulated heat through that layer of air-insulation…eventually.

To be clear, an aluminum stator-support does not stop the interior of the motor from getting hot, it simply cuts off the temporary heat spike peaks,  and then spreads that heat out, over time. On an extra-long uphill, a DD hubmotor with a cast aluminum stator support can still  eventually overheat if you keep hammering it, but…the interior aluminum mass will slow  the heat build up. What we need is a way to help the DD hub shed the interior heat faster.

There is only about one millimeters worth of air-space between the swept face of the stator electro-magnets, and the thin permanent magnets in the rotor. FF is a fluid that is drawn to magnets, where the magnetism of the motors’ rotor-magnets hold it in place (no leaks or drips), and…when you add about 10ml’s worth of it?…the heat in the stator electro-magnets is much more quickly moved to the aluminum side-plates so it can be shed to the outside air. The thin viscosity of the fluid still allows the rotor to spin easily, but the liquid FF fills-in the air-gap, allowing heat from the stator to flow quickly to the aluminum motor shell.

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Where is FF from?

Back in the 1960’s, NASA was pondering several ways about how to feed fuel to space-ship thrusters for maneuvering, without any gravity to pull the fuel towards the fuel-pump inlet. One engineer came up with the idea of suspending tiny ferrous particles in the fuel, and placing a magnet next to the fuel-pump inlet.

Later, in the 1970’s…the music speaker industry was looking for a method to draw heat away from the voice-coils in the high-wattage speakers that customers wanted. The speaker-cone has a large magnet attached to its center, and around it was a large electromagnetic coil. By varying the current to the electromagnet, the free-floating magnet on the center of the speaker-cone would be induced to vibrate back and forth, making sound.

When raising the watts that drive a speaker, you can reach a point where you overheat the magnet on the speaker-cone.

The problem was that the magnet at the center of the speaker cone would get hot when a high wattage magnetic field was applied (high-watt, to make it extra-loud), and its magnetism would be permanently damaged. They needed a way to get the heat in the free-floating magnet to be more easily shed, while not interfering with the speaker cone magnets’ ability to freely move back and forth.

The answer, was to take a very thin oil, and suspend ferrous particles in it. That “ferrofluid” would fill the air-gap between the stationary electromagnets, and the permanent speaker-cone magnet. Doing this transferred heat from the central speaker-cone magnet to the stationary voice-coil housing…where various other methods could be used to shed that heat to the air. Since FF is attracted to magnets, it sticks to the magnets and will not drip.

Ferrofluids are made up of tiny ferrous particles (often iron oxide), which are suspended in a thin oil (often synthetic low-VOC kerosene), with a surfacant added to prevent clumping or settling (usually some type of oleic acid). Depending on the application, there are many minor variations to the various recipes of FF.

Here is a youtube video showing how the FF aligns itself with the invisible magnetic field of the large and strong magnet under it.

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FF in hubmotors

FF does not help geared hubmotors, and it does not help mid drives. It is arguable that it may help non-hub outrunners, but…they already enjoy great success with air-fan cooling, due to their open framework, plus…the oil in the FF would accumulate dust and grit in any motor that is open to the air.

We wrote about cooling methods to help builders hot rod their hubmotors, and…back in 2012 there were two methods. First, you could cut holes in the sideplates of the hubmotor (ventilation) to simply let the heat out. This is what the Pikes Peak 111V racer did. However, this allows road-grit and rain into the inside of the motor-shell, so…it is important to coat the stator with a high-temperature water-proof coating, and use sealed bearings.

Sideplate ventilation holes on a large DD hubmotor. If there are cast ribs on the insides of the sideplate, do not cut a hole over the rib. This model has nine ribs, so there are nine holes located between the ribs.

The second method was that you could add a coffee cups’ worth of synthetic  automobile transmission fluid  (ATF) to the inside of your hubmotor, which works in much the same way as FF, because when the motor starts spinning, the ATF spreads out across the interior rim and connects the hot stator coils to the aluminum sideplates. ATF is cheap and available, but…it can sometimes drip and leak out, in spite of a builders best sealing efforts.

FF has created a whole new world of options for large DD hubmotor owners. Now, it allows you to raise the amps on your system to a higher level (add a temp sensor to the inside of the motor to avoid damaging it), and you can keep raising the amps until you reach our recommended max of 200F / 93C. Without FF, it wouldn’t take many amps to reach 200F, but…with  FF helping the motor shed heat to the outside air, you can use MUCH higher temporary peak amps during the acceleration phase.

[side note: if you add ATF to the inside of a hubmotor, you MUST also add a small pressure-equalizing vent to one of the sideplates, and if the vent is a threaded removable version, it can also be used for a fill-port. Without the pressure equalization vent, the heated interior will actually push the ATF out of every possible joint. Any humidity that is drawn in when cooling will be vaporised the next time the motor gets above 120F / 48C in normal use]

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Adding FF to a DD Hubmotor

First of all, this stuff is MESSY. Wear old clothes, because they WILL get stained. Wear snug surgical gloves, because this stuff is supposedly a skin irritant, and did I mention…it will stain everything it touches?

Removing the sideplate bolts with my favorite L-wrench using a 4mm hex bit. This is an Edge 1500W hubmotor with a 35mm wide stator, 12-ga spokes in a one-cross pattern, using a 19 X 1.6-inch moped rim, with DOT-rated moped tires.

The sideplate bolts (8 per side) are typically M4 X 0.70mm on hubmotors of this style and size, and I bought some stainless steel #8 washers to put on them when I re-assemble the sideplate. I know adding washers decreases the penetration of the stock bolt threads, but I believe they will still be strong enough.

Remove the axle-nut on the freewheel side, and place that axle-tip on some wood. Press hard and the cable-side of the hubmotor should pop out.

In the pic above, I have separated the hubmotor components by pulling out the cable side and stator as a unit. You “could” remove the sideplate on the other side without pulling out the stator, and then squirt the FF in, but…for me? I find that this method is actually easier. If you are going to drill a hole to epoxy-in a vent to the side-plate, now is the time to do it, and de-burr both sides of the hole. Here is one example of a sideplate vent. And also, here are some more examples.

WHEN RE-ASSEMBLING THE MOTOR, DO NOT HOLD THE SIDEPLATE EDGES WITH YOUR FINGERS. The very strong magnets will snap together with the steel stator core when they get close to each other, and it will crush your fingertips.  Hold the central axle when reassembling the hubmotor.

Of course, if you do re-assemble the hub by holding the sideplate edges with your fingers, the good news is that you won’t leave any fingerprints at the scene of your next crime. Then, your electric bike will allow you to have a silent getaway, but…make sure to install a PAS (pedal sensor), because you won’t be able to reliably operate a hand-throttle…

10ml is not a lot of volume. This is a 20ml syringe that’s filled to 50%, and a few drops of FF clinging to the rotor magnets. See the nine radial ribs on the inside of the sideplate? If you are going to drill ventilation holes in your hubmotor, place the holes between these ribs, and don’t cut the ribs. They may be small and shallow ribs, but you need every bit of strength that can remain after drilling.

In the pic above, you can Google “oral medication syringes” to find these for less than $0.25 each.

There is a formula listed below about how to calculate the precise amount needed to get the heat bridging effect, without adding so much FF that the rotor-drag is significantly increased. 10ml should be plenty enough for a large QS 205/H50. A MXUS 3000W will likely be fine with about 9ml, and for the 35mm wide stator hubs (Like the Leafbike 1500W and the Edge 1500W that I like) will likely work well with about 7ml. The common Yescom and 9C hubmotors with 28mm-30mm wide stators will likely work well with 6ml. I’ve been told you can actually just dump it in, and the magnetic fields of the rotor magnets will automatically spread it out evenly (if you have a vent hole already).

This volume needed was determined by builders measuring the very small “no load” amp draw of the motor (with the throttle on, and the wheel spinning in the air), and then they added more FF until there was a small bump in the no load draw, due to added drag.

Some builders have expressed concerns about centripetal forces sending some of the FF in the hubmotor out through the joint between the motor rim and the sideplates, so they have gooped that joint with a high-temp sealant. However, unless you are going faster than 40-MPH, the RPMs should be low enough that this “probably” wouldn’t be a problem. But…feel free to add some side-plate edge sealant if this concerns you.

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Adding Fins?

After some builders began enjoying measurable success using FF, a few builders pondered the possibility of adding some type of aluminum fins to the outer motor shell in some way, in order to help the heat-shedding process. Some suggested that the amount of extra heat-shedding that such fins would provide would likely be very small. However…temperature gauge readings and hands-on rider results have indicated that adding aluminum fins to the outside of the motor shell are a big help.

To be clear, aluminum fins added to the motor shell by themselves  have a small benefit (with no FF or ATF), but they do help some. However, if you are using FF or ATF to move heat from the stator to the motor-shell, adding fins has a much more dramatic benefit.

Using FF + fins is like 3 + 1 = 5, when it comes to heat-shedding.

There must be several shapes and locations of aluminum fins that would help, but one developer has created a kit of fin-sections designed to be clamped to the outside of the motor-shell rim. These are sold in six sections so they are small enough to be added to a popular and common size of hubmotor (with a 205mm diameter stator) without needing to remove half of the spokes. If your new hubmotor is already fully spoked-up to a rim, the fins can be added right away. The fins I bought for this article are called “hubsinks” by the retailer, and they are 15mm wide.

A tube of thermal paste, and the six hubsink sections, ready to bolt-on

The side-plates of these large DD hubmotors are made from aluminum, and they were made from that material because aluminum is light, it’s strong enough, and it absorbs and sheds heat well.  The outer rim of these hubmotors is steel, because it provides the magnetic-focusing backing material for the rotor magnets. It also provides the strong flanges that the spokes are attached to, and it is vital for those to be strong because the weight of a DD hubmotor can put a huge strain on the spokes.

It is the steel material in the motor rim that these aluminum fins will help. The amount of area where the steel rim is bolted to the edges of the aluminum sideplates is not very big, and…that creates a bottle-neck to moving heat from the stator to the sideplates (and then to the outside air).

Since the common hubmotor rims are a steel component…anything that can be done to shed heat directly from the steel motor-rim to the air  will help. The main reason I feel the rim-fins / hubsinks are important is because…they directly help to keep the temperature of the rotor-magnets lower. If you over-heat the magnets, the power level of their magnetism can be permanently damaged. The symptom of overheated magnets is that the top speed is now higher, and the power of the motor is lower (at the same input watts that you used before).

FF and hubmotor rim-fins go together in a very mutually beneficial way. However, if you don’t want to use both, definitely get the FF first.

[side-note: if you use motor shell rim-fins, you should spread out a thin smear of thermal paste between the motor-shell and the aluminum fins]

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High Performance Heat-Shedding Options in 2017

If your motor is only getting warm, you don’t need to add any extra cooling mods. However if you are raising the amps of your system to get harder acceleration? Here are some options. [warning: if you raise the amps too much, you might break something in your system…even if it doesn’t overheat the motor]

Geared hubmotors: two options…

• First is adding ATF and a tiny side-plate vent (and maybe hubsinks later?).
• Second is cutting ventilation holes into the sideplates, with the interior being coated with a high-temp motor epoxy.

Direct Drive hubmotors:

• First is adding ATF and a tiny side-plate vent (and maybe hubsinks later?).
• Second is cutting ventilation holes in the sideplates, with the interior being coated with high-temp motor epoxy.
• Third is to add about 10ml of Ferrofluid, and after that…maybe even aluminum rim-fins.

The header pic and this pic of a MXUS 3000W with FF and fins is courtesy of ES member litespeed.

The third option listed above is now my first choice. I always liked the idea of using ATF, but it seemed that no matter how well you sealed the sideplates to the rim with goop, there were still red oily drips on the floor, every where that you parked. And…I never liked the idea of a spinning motor occasionally flinging a drop of oil around near the brakes. Once the pads and wheel-rim (or disc) gets oily, its annoying to fix.

Builders who used the sideplate ventilation holes (with anti-corrosion coating over the entire interior), said that any moisture that got in was immediately vaporised by the motor heat on the next ride (like an automobiles’ open-framed alternator). They also stated that getting road grit and dust into the motor and bearing hasn’t been a problem so far. Sideplate ventilation remains a fast, cheap, and easy way to let the heat out of a race  hubmotor, but…I am still uncomfortable with the idea of using that method on a long-term commuter build, with an expensive motor that I want to last.

Any direct drive hubmotor will run cooler with FF, but…the motor that I think will immediately benefit the most from FF + fins is the Leafbike 1500W.  It does not  have the aluminum stator support that I have mentioned that I like very much (as a heat sponge). It had previously been my favorite middle-weight street-fighter to recommend, until the similar Edge 1500W  came along.

Both the Edge and Leafbike have thin laminations (to reduce eddy-current waste heat, and also to reduce cogging), and both have a 35mm wide stator, which is about the most power-potential a DD hub can have (in copper mass) while still leaving enough room to fit a 6-speed freewheel, and remain narrow enough to drop right into the common 135mm wide frame drop-outs (which allows them to still fit a wide variety of common bicycles). The major difference is that the Edge has the cast aluminum stator-support (So I immediately bought one as soon as they were available).

To compare, I would have to get a Leafbike 1500W and add a temp probe to it, then data-log identical runs against the Edge 1500W, with both using the FF and fins. That way the only difference would be the Edge’s aluminum stator-support. If the temp-limiting results were the same for both, then…the Leafbike would actually be the better choice, since it is a little lighter and slightly less expensive.

[side note: I have not forgotten about the MXUS 3000W with a 45mm wide stator, or the QS 205 with its 50mm wide stator. Both will benefit greatly from adding FF and rim fins]

I am currently happy running 52V X 50A = 2600W on my Edge 1500W hubmotor. However, I am now looking forward to getting a new controller so I can raise that to 52V X 80A = 4200W, so I can see for myself (be aware, I live where it’s flat, so…if you live in the mountains and fry your DD hubbie at 4200W, remember…I warned you). If this ends up the way that I think it will…this mid-sized DD hub with FF combo will be a total “sleeper” (a Superman, who looks like Clark Kent all the time)

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More FF info

Karl at electricbike-blog.com has also written about his experiences with FF. Don’t take just my word for it, check out what Karl says about FF in his article here.

I want to thank Richard Fechter for bringing up using FF for heat transfer in this July 2015 discussion thread. There was an earlier 2010 mention that had been ignored, found here. FF has been mentioned before that, but never for heat transfer in a DD hubmotor, until then.

Here is Bill Bushnells page on his FF experiments.

“If memory serves, the magic amount of ferrofluid is 1ml per 50cm^2 of stator surface area. Based on my own observations, as you increase the amount of ferrofluid [over that amount] you get slightly better heat-conducting at the expense of noticeably greater drag. Assuming the MXUS 3000W motor stator has a 20cm diameter, the sweet spot is about 5.6 ml. I’d probably err by overfilling it slightly at 6 ml to make sure I get most of the heat transfer benefit” -Bill Bushnell

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Written by Ron/spinningmagnets, April 2017

If…the idea of using cordless tool batteries to power an ebike has ever crossed your mind? You are not alone. After some research, I found out that…it is not as crazy as it might sound.

First of all, I have known for a long time that the 18650-format cells that are in cordless tools (18650 = 18mm diameter, 65mm long), are the premium cells that you would want for making an ebike battery pack. Its true that laptop computers also  use 18650-format cells, but…those are low-amp cells that compete on lowest price, not high-performance or long run-time. Just four years ago, pioneer ebike hot-rodders like Doctor Bass had to buy and gut cordless tool packs to get high-performance cells (now, there are hot-rod packs from many suppliers, like Luna Cycle).

So…this leads to a question. Which cordless tool packs can power an ebike? This isn’t a crazy question. International trade conflicts mean that at any moment, products from China can become a temporary casualty of a trade war (there is currently a trade deficit, meaning the US buys more from China, than China buys from the US). Trust me, all ebike products have some component that comes from China.

If there is a trade war, there will still be tens of thousands of cordless tool battery packs that are still in US warehouses. They will be waiting to be bought by construction contractors, but…if some of them are appropriate for our ebikes, right when you need one most? this article will try to help you identify which one are worth going out of your way to snap them up, before anybody else gets them.

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What Voltage?

First of all, we must limit ourselves to the voltages that are supported by common ebike controllers. The capacitors (inside ebike controllers) are the component that will limit the top voltage of the system. The common 36V, 48V, and 52V controllers typically use 63V capacitors. Then, the Low Voltage Cutoff  (LVC) is what really designates what a certain controller is suppose to work with (some controllers have a fixed LVC, and others are adjustable), and an LVC is important, because you never want to drain the cells to zero volts. Sadly, I haven’t found any good lithium cordless tool options at 48V (13S), so…

If we agree on a low voltage of 3.3V per cell for common 18650 chemistries (3.3V for long pack life, as opposed to a more common 3.0V per cell), then…a 10S and 14S battery pack would have an LVC of 33.0V and 46V…respectively, (commonly called 36V and 52V batteries).

Ebike battery packs made from lithium 18650 cells are considered fully-charged to 100% when they are at 4.2V per cell, so…a nominal 36V / 10S battery pack will have a top-voltage of 10S X 4.2V = 42V, and a 52V / 14S pack will have a top-voltage of 14S X 4.2V = 58.8V. The cordless tool battery packs we are interested in have a top-voltage of 10S / 42V…and 14S / 58.8V, commonly called 36V and 52V.

This is a typical lithium-Ion battery discharge chart. If you respect our opinion on this? Only charge your lithium battery pack up to 4.1V per cell. It will double the life of you expensive battery pack, as opposed to the commonly-used 4.2V per cell.

So…where does this lead us?…if you are happy with 36V (10S) and 52V (14S), then…you DO have some cordless tool options for your ebike.

It is possible to get 36V (10S) from connecting two 18V (5S) cordless tool packs in series (in fact, several manufacturers do this for some of their tools like Ryobi, Makita, Black and Decker, along with Greenworks). I don’t think this will ever catch on for ebikers, and the only 36V / 10S packs that “might” find a few EV users will have a full 36V / 10S voltage in one single pack (plus one single charger, instead of two 18V chargers).

Powered skateboards are growing in popularity. I am amazed that nobody has built them to accept cordless tool packs yet. Shipping lithium is a hassle with tons of liability, and cordless drill packs can be found in any major cities’ hardware stores.

[This web-magazine is focused on ebikes, but…we also love power-boards. Most of those  are using “Radio Controlled” (RC) components, and for good reason. That being said, common RC voltages are 18V (5S), 22V (6S), 28V (8S), and a few even use 36V (10S), or 44V (12S). If I was starting a power-board company? I would DEFINITELY  use an existing cordless tool battery pack as my interface. Why wrestle with shipping compliance and warranty issues when my product can simply use a battery pack that can be found at any Home Depot, Menards, and Lowes hardware store? not to mention Ebay and Amazon ]

If you are  interested in getting 36V by connecting two 18V battery packs in series, seriously consider the Milwaukee 18V / 9.0-Ah packs. In fact…if you are happy with 36V and 9.0-Ah…this would be my preferred battery pack, since the largest single 36V pack listed below is 6.0-Ah.

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Miscellaneous Notes

I don’t list anything from Ridgid, Skil, Festool, or Hitachi in the text below. Their lithium batteries do exist, but I haven’t found any worth mentioning for this type of application. Metabo and Hilti brands are high-quality and heavy-duty, but their batteries are only 18-volt and low-Ah, not to mention very expensive.

It’s my understanding that Milwaukee has purchased Ryobi and Ridgid brand names. It has been speculated that Ridgid is now their “affordable” brand, Ryobi is marketed as the mid-range home-owner “light duty” brand, and Milwaukee is advertised as their serious heavy-duty and high-quality contractor “use all day” brand.

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36V choices (10S)

There are several cordless 36V tools that use TWO of their 18V battery packs (mounted in series) to achieve 36V (like Makita). That is good for the contractor who wants more power than 18V (while still using his existing 18V batteries and chargers), but…I don’t think the 18V batteries will be popular with ebikers. However, there are actually quite a few 36V battery packs, though…

[be aware, if you are buying cordless packs in order to cut out the cells and build your own pack? The smallest packs provide the most amps per cell, because in order to get the minimum needed amps to power the tool with the fewest number of cells, the small packs have the highest current cells. The 2.0-Ah packs often have only five of the Samsung 20R cells rated for 22A per cell in a 10S / 1P  configuration, and the 5.0-Ah packs often have Samsung 25R cells in a 10S / 2P, rated for 20A per cell (2P = 40A total). The 6.0-Ah packs sometimes have the 30Q cell in 10S / 2P, rated at 15A per cell (2P = 30A), however…do your homework before buying any pack, and first buy just one to gut…before you buy ten of them]

The Bosch packs should be on the short-list for consideration, if you want 36V, or…72V with two packs in series.

Be aware, there are many 10S cordless tool battery packs (ten lithium-ion cells connected in series), that the manufacturer is calling a “40V” pack. Rest assured that all of the packs listed in this section are the same voltage, whether they are called 36V or 40V.

Kobalt

The Kobalt brand is the house re-branding name for cordless tools from the very large Lowes chain of hardware stores. The 40V Kobalt line has a 2.5-Ah, and also a 5.0-Ah size, the KB540-06

Ryobi

Ryobi products are typically found in Home Depot hardware stores. Their 40V line has a 2.4-Ah size of pack, a 4,0-Ah, and also a 40V 5.0-Ah…part number OP4050A.

Stihl

The Stihl brand is very well-known as a serious gasoline-powered gardening tool maker, like chainsaws. Their 36V AP-300 is a serious 6.0-Ah. In this video below, the smaller AP-180 is shown “opened up” for a few seconds, showing that is has 30 cells in a 10S / 3P configuration. 3P providing 6.0-Ah means each cell is a 2000-mAh, which suggests that they are likely the highest amp-producing cells available, and…that explains why Stihl is getting chainsaw-levels of power from only 36V, the Stihl tools use very high amps.

Troy-Bilt

The Troy-Bilt brand is listed as having a 40V 6.0-Ah pack, but…I can’t find any details about it so far. They want people to buy it, but I guess they just don’t want you asking any questions about the internal details…

DeWalt

The DeWalt 40V DCB404 is only 4-Ah (somewhat small), BUT!…the DeWalt 40V DCB406 is 6.0-Ah.

Bosch

I saved the best for last, and if you really want to use a 36V battery pack for an electric bike? seriously consider the Bosch 36V packs. Not only is Bosch a very large global brand that has a reputation for using quality components, they are the only 36V pack that uses air-cooling. In our article on making lithium batteries last as long as possible, one of the key elements was preventing them from getting too hot. I’ve only found two brands that have this air-cooling feature, Bosch and EGO.

The Bosch charger definitely blows air through the battery pack when it is charging. I haven’t found proof yet that it gets powered air-flow when you are running  the tool, but…their engineers are nuts if they didn’t do that. But…even if they don’t...the Bosch 36V / 10S pack system has a 6.0-Ah option for their mower, so…it’s at least as good as the other options above. If the 6.0-Ah pack is fan-cooled when it’s running, then it is the clear winner. At he very least, it’s construction allows an ebiker to add a fan to it, and the others do not.

Husqvarna and Craftsman are generally considered fairly decent brands, but…their only 40V packs are small (4.0-Ah, or less)

If you Google 36V and 40V battery packs…you will also come across the off-brand names Enegitech, Earthwise, Lynxx, Sun Joe, Oregon, and others. I have no experience with these, but I suspect they use some pretty generic cells with a cheap BMS and a cheap charger, so I don’t recommend them. If you try them out, please post about them on the internet (and send me a link), whether the results are good or bad.

Hilti makes a rock-solid 36V / 6.0-Ah pack made from only the highest quality components with a bomb-proof warranty, but…did I mention? Its over $420 for only one of them without the charger…yeah.

Conclusion for 36V packs

I do not consider 6.0-Ah to be a very big pack (for an ebike, at least), but…if your ebike can “get by” with this size, then…the 10S DeWalt, Troy-Bilt, Stihl, and Bosch all have a 6.o-Ah battery pack model available. Prices vary, so shop around…(don’t forget the option of using two Milwaukee 18V / 9.0-Ah packs in series)

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48V

I had really hoped I would find at least one cordless tool lithium battery pack that used 48V (13 cells in series, 13S). The few 48V devices I found (lawn mowers, etc), turned out to use lead-acid batteries. If you find any, please send me a link.

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52V choices (14S)

This is the jackpot for cordless tool batteries being re-purposed as ebike packs. Before we get started here, a large direct drive (DD) hubmotor draws very high amps for the first few moments of acceleration. How high? well…how much money do you have? Speed costs money, and large DD hubs can take as much as you’ve got. I don’t  recommend cordless tool packs for a large DD hubmotor…

However, mid-drives such as the popular Bafang BBS02 and BBSHD typically only draw 25A-30A when using the stock controllers. Their controllers will also run off of a 48V pack or a 52V pack. There are several selections listed here that will easily provide 52V and 30A. There are even small geared hubmotors that would be happy with 52V / 30A, without straining the battery packs.

When a pack with 14-cells in series is fully-charged to 4.2V per cell, the packs’ top voltage when hot off the charger is 58.8V. The nominal “average” voltage is commonly referred to as 3.6V per cell, so the 14S nominal voltage is 14S X 3.6V = 50.4V…

Some ebike 14S pack sellers call their packs 50V, and others call them 52V, but…if they use lithium-ion cells? They are all the same exact voltage. That would be 50.4V nominal up to 58.8V when fully charged. The internationally-recognized standard for DC voltage to penetrate dry skin is 60V. The starting voltage of these 14S packs just barely misses that, but…after only a few moments of run time, the pack will settle into the long “nominal” voltage portion of the discharge that is near a much safer 52V.

Worx

The Worx brand weed trimmer is listed as 56V, but it appears to be physically identical to the Echo 58V. There are teardown videos of the Echo battery (see below), but I haven’t found video of the Worx pack interior to verify my theory that they are the same.

Echo

These Echo packs are called 58V, but they are definitely 14S, so…they have the same voltage as the other packs in this section regardless of the voltage in the name. The Echo engineers wanted their packs to be as compact as possible, so they are mounted in a tight cube. That does  make the pack small, but…it also restricts airflow through the pack, making the cells in the center of it warmer than the cells at the edges. Heat is bad, and it is very beneficial if you can avoid that as much as possible. It doesn’t matter how long the cells around the edge survive, if the cells in the center die an early death, the whole pack immediately becomes trash, amirite?

The largest Echo 58V pack is a modest 4.0-Ah, and this is another way in which their weed trimmer is kept to a very light weight, but…it also hurts the mowers run-time (they both use the same pack, with the mower using two of them, and the weed trimmer using only one). However, there are  options, so…keep on reading below!

EGO 56V

Buckle-up, because this section is going to be an earful. Fair warning, I am a huge fan of the EGO batteries. In the interests of full disclosure, I have never received anything for free from EGO, and I paid the full retail price for their weed trimmer and lawn mower, both purchased at Home Depot.

The EGO 4.0-Ah pack for my trimmer, and the monster 7.5-Ah pack for the mower (they also carry 2.5-Ah and 5.0-Ah packs). The banana-for-scale is calibrated in 4-inches and 10-centimeters.

Not only does EGO use high-quality name-brand cells, they have done four specific things to keep the cells as cool as possible, which is why the EGO packs should last much longer than the other brands.

1. Each cell has a PCM sleeve to absorb heat-spikes. PCM is a “Phase Change Material“, and the All-Cell  company is famous for inserting their cells into a large block of PCM to help manage battery heat. With this type of PCM, it doesn’t change from a solid to a liquid, it’s more like changing from a hard rubber to a soft rubber, when the cell gets hot. During that process, it can actually absorb a surprising amount of heat. The heat still has to be dissipated over time, but this simple addition limits the highest portion of the working cell temperature peaks.
2. Speaking of dissipating that stored heat that was absorbed by the PCM sleeves, these packs have an unusual shape that spreads the cells out, instead of bunching them up in a block. This helps air-circulation, which is vital for the next feature…air-fan cooling!
3. These packs from EGO are not sealed, they have channels that allow fans to blow air through the packs when they are being used, and also when they are being charged.
4. The last feature that helps these stay as cool as they can be…is their size. The EGO mower does have an UN-exciting 5.0-Ah pack available, but I opted for the 7.5-Ah, which is the largest cordless tool battery pack I have found (other than the backpack batteries listed farther below). A 7.5-Ah is not only the best range of a cordless pack, it’s size means that each individual cell is less stressed, and will run cooler than it would if you were pulling the same amps from a smaller pack.

Since these EGO packs require an open architecture to allow for the awesome fan-cooling feature, the electronics are all fully potted in epoxy against rain and accidental splashing. I’m sure the various brands of mowers and weed trimmers have a performance that all work about the same, but…it was the batteries  that made me a fan of the EGO brand.

The insides of the 4.0-Ah pack

I now own a mower and trimmer, and I can verify that they are pretty damn great. I don’t need earplugs like I did with the loud gasoline mower, and it is quiet enough that I can get up early in the summer to mow, instead of waiting until later when it gets hot…and I used to do that so I didn’t wake up my neighbors who are trying to sleep-in on a Saturday.

One other great feature is that I own two 52V ebikes, and…when they get to being several years old? their capacity will eventually erode down to 14-Ah from the original 17-Ah (as all batteries do, regardless of manufacturer). When that happens I will buy a new 52V battery pack for my ebike, and the old pack can be used for the mower until it is completely dead. At a well-worn 14-Ah, my old ebike pack will still be almost twice the capacity of the stock 7.5-Ah EGO pack when that one was new.

Here is a teardown video of the Echo and EGO battery packs to show the insides:

Here’s another wrinkle. In a power outage, how many batteries do you have that can keep your smart-phone, re-chargable flashlight, and laptop computer charged for as long as possible? I have a small DC/DC converter that takes the 52V and produces 12V for my ebikes lights and radio. That 12V socket can also keep my phone, 18650-cell flashlight, and laptop charged up for a very long time, by using my 52V ebike batteries…and…my EGO lawn mower batteries!

One last note, the large 7.5-Ah pack will not only run the mower for which it is designed, it will also run the string-trimmer, which of course would make the trimmer a little tail-heavy. The smaller 4.0-Ah pack WILL NOT run the larger mower, and there is some voodoo involved by EGO to prevent you trying that. Both chargers will charge either pack, but…only the charger for the 7.5-Ah pack has four LEDs to show the state of charge.

[side note: EGO has two sizes of mower, I purchased the larger one for an extra $50 because it has powered wheels as a RWD. The smaller mower has a base-model 5.0-Ah battery pack. The 7.5-Ah battery alone is worth the extra $50]

I was so disappointed years ago when I tried out an 18V string trimmer. Others have come and gone (24V, 36V), but…this was the first time I was willing to give it another try, and I am VERY satisfied.

I charge them to 75% immediately after mowing (three LEDs out of four), and then I only charge to 100% just before mowing. If you store lithium-ion battery packs at 100% charge, they will die much sooner than necessary. Store them at 90% or less, in accordance with the information we researched, found here. Doing this can double the life of your expensive packs!

Here’s another article on the EGO 56V batteries by one of my favorite writers, Karl.  It’s from a year ago in April 2016, and this article convinced me to actually buy an EGO 56V weed trimmer, instead of just reading about them.

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DeWalt 60V

I originally thought that the DeWalt 60V packs must be 14S (fully-charged 14S packs are 58.8V). However, a teardown video showed that they are definitely 15S. A nominal 3.6V per cell would be 3.6V X 15S = 54.0V, and fully-charged they are 4.2V X 15S = 63.0V

This is cutting it real close to popping the 63V capacitors inside the popular Bafang BBS02 and BBSHD controllers. A small geared hubmotor wouldn’t care, as long as the easily up-gradable external controller was made for that voltage range, but…why use the odd voltage that nobody else is using? After looking into why, it’s actually quite clever what DeWalt did with these (warning! If you are uncomfortable with rough language, then don’t click on this AWE-some battery teardown video link)

Every major cordless tool manufacturer on the planet has a variety of 18V tools, which use five cells in series (5S). DeWalt created a clever 20V / 60V pack with 15 cells inside.

The interface is made so that…when it is plugged into a 20V tool, the pack is automatically configured as a 5S / 3P pack…with a VERY long run-time. However, when you want to use that battery pack on a more powerful 60V tool, you just plug it in, and the tool interface will automatically configure the pack as a 15S / 1P pack. High power, but with a short run time.

I know of one builder who is using these on his BBS02 ebike, and I wrote about it back in January of 2017.

Blairs BBS02 DeWalt Cruiser

Snapper 60V

If 15S interests you, the Snapper brand “might be” a better bet. It has a 15S / 2P pack that is definitely 30 cells at 4-Ah (with no fancy 20V / 60V switching like the DeWalt). However, even at 2P, it does not have very much range, so you will have to add several of them, just like Blain’s BBS02 / DeWalt cruiser listed just above.

Greenworks 60V

I couldn’t find any battery pack teardown videos for these, but it uses TWO small 2.0-Ah packs to get a decent run-time from the mower (instead of one large 60V pack). The weed trimmer only needs one of these 60V packs at a pretty small 2.0-Ah.

Black and Decker 60V

B&D is still selling 36V lead-acid mowers, so its no surprise that their new lithium mowers use an existing system (rather than invest in a risky new-to-them format)…yup, the dual small 60V packs look identical to the Greenworks packs listed above. Each brand of mower does  have differences in their features, but…both of them look like they use the same battery system. There is no word on whether both of them use the same 18650 cell, or what that cell-brand and chemistry that they might be. Both use small 2.0-Ah packs…

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80V / 20S Systems

I don’t recommend these for ebike experiments. Not only is the higher voltage un-necessarily more dangerous, but…if you truly want to run 20S, I feel it would be easier to adapt using two large 10S / 36V packs in series. That being said, they do exist.

20S would be  a nominal 3.6V X 20S = 72.0V, and when fully-charged?…it is 4.2V X 20S = 84.0V

Snapper

The Snapper brand has an “82V” series (with a respectable 4.0-Ah size) that is made in partnership with Briggs and Stratton. B&S is no stranger to electric motors, and their ETEK motor is an ebike hot-rodders favorite…found in floor scrubbers and lawn mowers.

Greenworks

The Greenworks brand has an 80V mower, and the larger 4.0-Ah pack looks identical to the Snapper packs listed above. They also have a smaller mower that uses two 80V / 2.0-Ah packs, instead of one large pack.

Kobalt

This is the house-brand for Lowes, and the only size pack I can find is the 80V / 2.0-Ah

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Making Mounting Adapters

No matter what size and type of cordless pack you decide you want to use, you will have to make mounting adapters for each pack. In the video tutorial above (for Blairs DeWalt Cruiser), he cut the bottoms off of six DeWalt worklights, since they were the least expensive DeWalt tool that had the slide-in interface for the batteries. Some builders have the tools and skills to make mounting adapters from scratch, but I believe most cordless battery ebike users will have to allocate some of their budget to buy a cheap tool to sacrifice (or buy a used tool at a pawn shop, or from ebay?).

Also, save the lights you cut off, they can still be used! three of the 20V lights “in series” can use the 60V battery pack voltage directly without a converter.

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Backpack Batteries

Cordless tool manufacturers want contractors to use more cordless electric tools, but its been a slow climb for them. I may only spend 30 minutes mowing and trimming my lawn and bushes, but…someone who does that for a living will go from lawn to lawn all day long. The only way I could see me using cordless electric lawn tools for a business  is if I used the cordless electrics early in the day, in a neighborhood where the gassers are too noisy to use before 8:00-ish. After 8:00? I’d switch back to gasoline.

That being said, they are making an effort to provide larger batteries for more run-time, and one logical product to offer is a back-pack battery. I could only find three brands right now. Greenworks, Husqvarna, and Stihl. They are expensive per watt-hour, compared to clustering several smaller tool packs like the units shown above. The ads show them being used with cordless electric chainsaws, and various other tools. If you can swallow the price on these, they would  make the chainsaw lighter when you are crawling around the branches of a tree when you are 20-feet above the ground…

I doubt the Greenworks backpack is selling well, since it is 82V and only 12.5-Ah. There is only so much room for cells in a pack of a given size, so the more volts you want, the fewer amp-hours you will get. Their GL900 is listed as $900

Husqvarna and Stihl both have large 36V backpack batteries.

Husqvarna

Husky makes a couple of sizes of backpacks in 36V. The BLi520X is 14.4-Ah and retails at $600…and the BLi940X is 26.1-Ah and $950.

Stihl

These two guys (Husky and Stihl) seem to constantly compete with each other, so of course Stihl also has 36V backpacks. The AR900 is 24-Ah, and costs $850, and the AR3000 is the largest one at 31-Ah, selling for $900.

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DANGER!

There is one huge issue with combining several small battery packs onto one ebike. You can attach two packs together in series without immediate damage (as long as it’s done right). In other words…an 18V pack attached to a 36V pack IN SERIES will make a 54V pack. Sounds odd, but it works.

However, if you are running two or three packs IN PARALLEL (in order to have a longer range without needing to occasionally swap from one pack to another), you absolutely MUST charge and discharge them all at the same time, and when you insert them into the mounting harness…if one of them has a lower voltage than the others? all the packs will rapidly equalize. This means a LOT of heat, possibly damage to one of them, but whats worse? It can cause a fire. This is no joke.

If you have two mounted packs (or more) and you install a switch to move your ebike power from one pack to the other (instead of physically pulling one pack out of a mounting slot and sliding a second pack into it), make sure that the type of switch you use has a neutral center position where nothing is powered.

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My Recommendations?

Stick with a large global retailer of well-known “heavy-duty contractor-grade” tool batteries, like Bosch, EGO, Milwaukee, DeWalt, Makita, etc. Use a voltage that fits right in with a common ebike controller voltages, like 36V or 52V. Do NOT alter the batteries themselves, so technically you might be able to use the factory warranty if you get a defective unit. The on-board BMS’s and temperature sensors will not allow you to draw more amps than they can safely provide, so they should last a very long time…even on an ebike.

Fan-cooling the interior of the packs is a HUGE benefit, so I would encourage anyone to make every effort to find a way to get the 56V EGO or 36V Bosch packs work for your application.

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Written by Ron/spinningmagnets, May 2017

Normally, I wouldn’t care much about a turn-key ebike that uses only 350W, but…the Specialized Turbo Vado-S shows that the E-division of one of the biggest players in the bicycle market is evolving. And…it doesn’t hurt that they are moving towards a direction that we have been talking about for a long time.

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The Vado-S, and its Major Features

If you Google the “Specialized Turbo” you will still find a rear hub-motored ebike. Although the Specialized Turbo is about as good as a low-powered hub-motored ebike can be (it is VERY sophisticated)…it is still struggling to make progress in North America. One reason is the high price tag, and the other reason is the low power.

There are plenty of retailers who are trying to sell turn-key factory ebikes (instead of a kit that is added to an existing bicycle frame), and…why not sell something that is already in production? So…there are two huge markets for existing ebikes. The first is China, and…the second is the European Union (EU). The Chinese public seems to care only for adequate performance and lowest price (I’m not judging them, but..those ebikes are ugly by US standards), and the EU market seems to care about…high quality and style…along with buying ebikes that “look like” a regular pedal bicycle, and only provide “mild assistance” when pedaling…meaning no hand-throttle).

That means that…passionate ebikers in North America have two choices. One is to buy an EU-spec factory ebike that is very high quality and low-performance, or…buy a cheap and high-performance kit and install it on an existing bicycle. In the interests of “full disclosure”, I have several ebikes, and they all of them have kits that are cheap and high-performance. I live in Kansas (central USA), and when I pedal past the police, my most-often-used  ebike has more than twice the legal power limit of 750W for the USA (it’s 1500W, for the “math impaired”).

I ride the streets, and I have “almost” been killed by cars several times. I cannot imagine having any less power than what I have now, as a matter of survival. That being said…there are several things I like about the Specialized Turbo Vado-S.

The Specialized company is huge, and it is a global bicycle powerhouse (both for street and off-road). I was happy to see that they were finally making an ebike model, years ago. It is true it was a rear hubmotor, but..those can be “adequate” for terrain that was fairly flat (with a few mild hills), which is what most major cities are around the world. I can’t blame them, but…

Here, we are un-embarrassed fans of “hot rodding” and…in the tradition of historical European car races…”racing improves the breed”. If you trust us? Our experience tells us that…the more power you have, the fewer gears you need. So…Specialized has made progress by introducing the MID-DRIVE Vado (which at least, has “some” gears), but…it is still an “efficient low-powered” EU-spec ebike that they are trying to market where-ever they can.

Don’t take this as a harsh criticism. Specialized is a very successful company that is marketing exactly what EU customers want, in an era where gasoline costs $8/gallon in Europe. However…the law in Canada allows a 500W power limit, as does the “hilly” nations of Switzerland and Austria (have you heard of the Alps?).

Why won’t they build a street-LEGAL 750W ebike for the US, and then just restrict the amps to make it a 500W legal ebike for Canada, Switzerland, and Austria? These global ebike engineering divisions of bicycle manufacturers are pandering to their biggest customer base, therefore…I can’t really blame them, so…for the next few years, North American ebike enthusiasts will have to make do with adding a kit that they like, and adding that kit to a frame that they like.

So, let’s get back to the Vado-S, and why it is a milestone. By producing the Vado-S…Specialized is admitting that street ebikes that only have a hubmotor (and are limited to 20-MPH, 16 km/h) are no longer viable for most of the buying public (DUH?). Would YOU pay $5,000 for a 20-MPH ebike, that struggles on hills? In fact, a huge portion of the new ebike buyer base is an older bicyclist who just need a little help on the hills.

The big change for Specialized in producing the “mid drive” Vado is that they realize some customers who ride on the streets? They want an ebike that can shift gears to climb hills better. The “S” designation is also especially important. In the EU, it means that the model in question is a “Speed” pedelec…meaning that, when you pedal along?…the power system will add electric motor power up to 28-MPH (45 km/h). I personally find that this particular speed is actually reasonable for legal ebikes on the streets (with no required registration or licensing). You can pedal up to a much higher speed on a downhill, but…you won’t get any extra electric  power over the 28-MPH limit…

This is a cool “exploded” graphic of the hardtail Specialized Vado.

The Vado comes in four versions, meaning…two top-speed limits (20-MPH, and 28-MPH), and two 36V battery sizes, providing up to 90Nm of torque (Newton meters) at the pedal-axle. The motor itself is the same as what’s in the standard off-road Specialized Levo, but the software is re-tuned for street riding. The 250-watt Turbo 1.2 Motor goes in bikes that top-out at 20-MPH (32 km/h), and the 350 watt Turbo 1.2 “S” will provide a 28-MPH top speed (45 km/h).

The Brose high-efficiency mid drive motor and controller unit, courtesy of the UK website, ebiketips

From the pic above (courtesy of ebiketips, in the UK), we can see that this particular Brose unit uses an aluminum “bathtub” lower case-housing, which the motors “in-runner” stator is heat-sinked to, in order to provide air-cooling across the shell, while keeping the motor itself sealed away from mud and water. Plus, the primary gear-reduction uses helical gears to reduce high-RPM noise, and…the secondary reduction uses a belt instead of a chain to make the drive as quiet as is possible. The last engineering note of interest is the use of the ISIS splined crank interface, instead of the common square-tapered spindle (which is definitely an upgrade).

In researching links to find out info for this article, I stumbled across the youtube linked above, and in it, I also saw some info I had not seen before. In spite of the fact the Brose drive-unit used only 250W / 350W of input power…the axle-spindle was an unusually high-quality of design and strength, along with the freewheel.

In the pic below, the freewheel shown is a type known as a “sprag” clutch. It is commonly used in industry, and is known to handle very high power per a given size, but…it is also more expensive than the more common types of freewheeling clutches. I have read that the Brose unit was designed by an engineering group that included automotive engineers, and I can’t help but to notice that helical  planetary gears and sprag-clutches are common in automotive automatic transmissions…

The tubular Brose ISIS splined axle-spindle, shown with a high-number contact-points sprag-clutch, and a multi-point magnetic motion-indicator. I can’t tell the exact number, but it looks like it has approximately 36 tiny magnets, so the distance between them is very small. This means the pedal-sensor has a more precise and rapid picture of whats going on in the system. Many other brands use only 12 magnets.

There are three common types of freewheel-clutch (a shaft will spin freely in one direction, but locks-up in the other direction).

The three common types of freewheel clutch. A sprag on the left, a ramped roller is in the center, and the common bicycle pawls are on the right.

It is very unusual for an ebike to use a sprag-clutch as a freewheel. It is even more unusual for a low-powered ebike to use that. The sprag-style is known to be smooth and quiet in its operation, but…it is also known to be capable of very high power transmission in a compact package. The only downside is that it is more expensive than the other types, even in its simplest form. Its strength and its expense is a result of its high-number of contact points.

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Other Specialized Vado features

In the pic below, you can see the “Dry-Tech” fenders, which dramatically reduce the water that is splashed-up onto the motor and rider when riding in an unexpected and sudden rain. The main fender design change is that the front fender has a rubber-flap extension on the trailing edge (shown by a red arrow), and it may seem at first to be only a minor and simple improvement, but…it does significantly reduce the amount of water that is splashed-up onto the rider and ebike.

The Specialized Vado-S, notice the kick-stand moved back to near the rear axle so it doesn’t clash with the pedals when rolling backwards, and the cables are routed through the frame, inserted at the head-tube.

I also like the custom-designed cargo rack. it’s unusual shape allows a Thudbuster or a Suntour NCX suspension seat-post to be added without the cycling stroke of their mechanisms to be limited (I highly recommend either of them). A proper suspension seatpost is the single most appreciated upgrade to a hardtail frame, especially for the “S” model, which can be powered up to 28-MPH (45 km/h).

The Specialized Vado rear disc brake

The Vados’ rear disc brake caliper is located inside the frame (instead of the more common location above the seat stay). That is a minor change, but…I like it, and I think many potential buyers will like it too. I recently saw an article on the increased use of disc brakes on bicycles of all types, and…for bikes at speeds above 20-MPH (35 km/h)…I definitely approve.

Here is the 10-speed cassette sprocket-cluster on the rear wheel, that I feel is very appropriate for a 350W ebike mid-drive. Since the Vado-S only has one chainring, the entire gear-range can be very cheaply adjusted up or down with a simple and affordable chainring swap.

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The Specialized Turbo Vado. It is made to be a stealthy and almost-silent ebike, for streets and mild trails. the model shown here only has the solid fork.

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The Specialized company is based in Switzerland, and many components are made in Germany.

There is nothing wrong with a male enthusiast buying and using a Specialized Vado or Vado-S, but…their advertising program and color selections seem to indicate that the Vado is being marketed to women. This is not a bad thing, but…the max-power 350W Vado-S indicates that Specialized thinks that ALL women only want “mild assist”.

The EU-spec ebike pedelecs are very sophisticated ebikes that take an efficient and  small-watt power input and convert it into a lot of wheel-torque, but…will it sell in North America?

The past year has seen a LOT of bicycle media ending up softening a little bit on their previous hate of ebikes. The Specialized Turbo Vado-S is typical of the ebike versions that attempt to seduce bicyclists to “come over to the dark side”. From a distance, they actually look just like a “pedal-only” bicycle. That being said, the extra power of a battery and electric motor allow the rider to climb up steep hills with no sweat. Of course, the lower power range of the 350W EU-spec system means you will have to downshift into a much slower gear to do that. the upside to that is…the small and light battery will last along time (but…get the larger battery, you won’t regret it).

Brose and Specialized need to come up with a US-legal 750W version that can easily have its amps limited to make it a 500W version for the Canada/Switzerland/Austria customer-base. These modern sophisticated versions we see are very impressive with how much wheel-torque they can produce from a measly input watt amount of 350W, but…I’d like to see what they could do with 750W 0f input (don’t you?). And for those who fear the customers with a mind-boggling power level of 750W at their fingertips?…each rider can use the dashboard to quickly and easily limit their watts to less, if they want more of a leg-workout on their ride (I use 1,500W on a mid-drive often, and its still not enough for me).

(*sigh) Here’s a quote from “Bike Radar” that shows that the current US bicycle media is growing to accept that…maybe ebikes are actually here to stay? The Vado-S is mild instead of spicy (by our opinion), but…it is progress.

“…The Turbo Vado has opened my eyes to the true potential of e-bikes, call it an e-piphany. Here we have a vehicle that could genuinely get people out of cars for a commute that’s as much of a workout as they want it to be, and can even deliver fun in the process…” – Bike Radar

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Written by Ron/spinningmagnets, May 2017

High-capacity packs using 18650-format cells have become popular, and we will have some interesting options soon with the new 21700 cells that are just now becoming available.

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Some EV battery history

Many years ago in the early 1990’s (just when GM was confiscating and crushing the existing EV1’s), the founders of the start-up called Tesla were test-driving the T-zero prototype and contemplating what a successful electric car drivetrain would look like.

I am normally skeptical about most conspiracy theories, however…I read that at that time, the most common large-format battery was the NiMH cells that were used by the Toyota Prius and the Ford EV Escape. The global oil-conglomerate Chevron-Texaco purchased a controlling interest in Cobasys, who had owned the patents on those cells. I had hoped at the time that this indicated a shift in the powerful oil-company paradigm of their recognizing that they needed to evolve, and become a big player in the EV field, instead of competing with them. Someone with “big money” was finally investing in EV’s!

The common 18650 cell is the size of an adult finger.

Instead, their newly-found control over the large-format NiMH cells was used to severely limit their use. This forced Tesla to focus on using thousands of small 18650 lithium cells as the next best alternative. This ended up being a good thing. In spite of the extra time and effort to design and manufacture a large pack out of thousands of smaller cells…I am only recently seeing the benefits of how heat affects lithium cells (and having many small cells helps their heat-dissipation), and how individual cell-fusing means that…if one tiny cell out of thousands fries, the pack as-a-whole will continue to work safely.

Lithium-based 18650 cells (18mm diameter, 65mm long) came-to-fame  as the cell of choice to power laptop computers and cordless tools. Laptop cells compete on lowest price, but…it is the cordless tool cells that compete on performance and long run-time. Those are the premium cells that ebikes need and love.

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What about 26650’s?

The 26650 format already exists (26mm diameter, 65mm long), and I have occasionally read of people who wondered why Tesla (and others) didn’t just use this existing format. I honestly don’t have a solid answer, but the most likely culprit is that a fatter cell has a lower ability to shed heat that is located at its core. I recently wrote about the Lithium battery lecture by Prof. Jeff Dahn, and heat-management is one of the major factors in getting a battery to last as long as possible. Tesla has an unprecedented 8-year warranty on their packs, which is pretty amazing, so…they are doing something right (note: keep your battery cool, and charge to 4.1V per cell).

The 26650 cell is on the left, a 20700 is in the center, and a common 18650 is on the right. 26mm diameter is very close to one inch, which is the diameter of a US quarter coin.

There are a lot of ebikers who would prefer using 26650 cells…if…they came in a variety of Ah’s and amp-producing versions. However, the 26650 cell selections that are available now are very slim-pickins at best.

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18650 cells

The INR prefix is generally regarded as designating that a cell chemistry is “NCA” or Nickel Cobalt Aluminum. This is what Tesla uses (but…there are also several variations on the NCA recipe). The NCR prefix is the “NCM” chemistry, Nickel Cobalt Manganese.  Listed below are the recently popular high-capacity cells on the market.

10A, 3.5-Ah, NCR18650GA Panasonic / Sanyo

10A, 3.5-Ah, INR1865035E  Samsung

10A, 3.5-Ah, INR18650MJ1 LG

When these companies say that a certain cell is “rated” for 10A continuous…what does that actually mean? It may be listed as a “continuous” current rating, but…if you draw 10A continuously, what actually happens (does it get hot, or only warm)? Clearly, these cells can temporarily output a higher level of amps than that for a few seconds, but…factories don’t like to advertise that…using them that way will erode their range, and also some of their life.

Here is a cutaway graphic of a popular “dolphin” hard case battery pack, with the cylindrical cells mounted sideways.

I’m still annoyed that every major battery manufacturer has not been honest and forthright about how charging to 4.2V per cell will dramatically reduce the life of your expensive pack (every “official” factory spec sheet still lists the charging volts as 4.2V per cell…WTF?). This is the default charging level for the battery chargers that are commonly purchased. By charging to only 4.1V per cell, you might be able to double the life of your expensive battery pack (OR MORE!). Are there any lithium pack chargers that will balance every cell when only going to 4.1V? If no, then…why not?

This is the truth, regardless of the brand of cell, or vendor that you like. As a result, I prefer to design my personal systems to use a cells “factory continuous” rating as my “temporary peak” rating. My packs run cool, they provide the max miles possible, and…they live a long time.

That being said, I am collecting information about the HEAT that results from the current draw on various popular cells. In my mind, the resulting heat is what actually determines a cells amp-producing capability. So…why can’t I find a chart of amp-draws and the resulting heat for popular cells? Maybe something that is easily repeatable to verify it’s accuracy?

The three cells I listed above are the most popular for range, and I suspect they will grow to be even more popular over time, due to their fairly decent performance (a reasonably small 4P pack of 10A cells can produce 40A…nice!). However, if you are a hot rodder…the cells below are on the short list of high-amp “hot rod” cells I have recently seen to be frequently used.

15A, 3.0-Ah, Samsung 30Q

20A, 3.0-Ah, LG Chem HG2

20A, 2.5-Ah, Samsung 25R

30A, 2.5-Ah, Sony VTC5

I am listing high-capacity and also high-amp 18650 cells here, so you can compare them to the evolving 21700 cell options that are just now becoming available.

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Panasonic 20700’s/ Tesla 2170

The history of formats is a subject that can give me a headache and indigestion whenever its brought up (VHS vs Betamax, DVD vs Bluray, etc). If I was consulting for any device manufacturer, I would push the 21700 format (21mm in diameter, 70mm long). For some reason that only Panasonic knows, they have come out with a very minor variation of a 20700 cell (20mm diameter, 70mm long).

One millimeter is roughly 1/25th of an inch, so…if you have both a 20700 and 21700 cell in your hand, you probably couldn’t tell the difference between them, but…these kinds of proprietary variations drive me nuts. Samsung even now has a 20650 format (there are various reports that the 20650 format was started, and then discontinued…who knows? LG has a model 20650 M42 = 15A and 4.2-Ah, model 20650 HG6 = 20A and 3.0-Ah).

The little central “nipple” at the bottom left is the only place you can draw the positive from. This is the “cathode” connector. The flat bottom-plate and also all of the sides of this cylinder are the negative electrode, the “anode”. Remember!…if you cut through the sides of the thin plastic wrap, the metal sides are HOT with the negative electrode. Please do not burn down your house with an ebike fire because you didn’t realize this…

This means that once a consumer buys a certain device, they are then (hopefully) locked-in to buying only a certain format of battery cell. The joke is on them, because China is famous for filling-in any weak business strategy gaps. A small adapter can be added to make a 20650 cell fit in a 20700 slot, and a 20700 cell will easily fit in a 21700 slot. If you are designing a device that you want to be relevant over the next decade, make the slots to fit the physical dimensions of a 21700 cell.

The Tesla car company is the proverbial 500-lb gorilla of the evolving EV market. When they sneeze, everybody in that world gets a cold. A short while ago, they announced that they would partner with Panasonic and build a huge factory to produce cells for the next generation of Tesla cars, and this new “Gigafactory” would be located in Nevada, USA.

That factories’ production capacity initially sounded a bit optimistic, but then…Elon Musk announced that Tesla would be producing a “power wall” device (a flat, wall-mounted battery pack), that would also  eventually use those same cells. This power-wall bank of cells can provide power to your home during a temporary power outage. It can also charge up in the middle of the night (when electricity is cheapest) and then assist during the high-demand part of the day. This allows states to build fewer electrical generating stations in the near future.

Of course, the powerwalls’ primary market is as a storage device, so home-owners can soak-up solar energy with PV panels when they are at work, and then draw from the battery pack in the evening.

Some of the internal structure of the common 18650 cell. All of the additional mass of the 21700 format is in active battery material alone. Graphic courtesy of Hitech Energy.

Back in the early days, it made sense that Tesla should use an existing battery cell format (even if Chevron hadn’t limited them), but now?…their huge cell-production projections meant that they can easily afford to create an entirely new format that is maximized to meet the demands of their near-future EV designs, and also the Tesla power wall.

That new format is the 21700 cell (sometimes referred-to as the 2170 cell in many places). It has been claimed to have 40% more active battery volume, even though it is only slightly fatter and taller. That is more believable once you realize that there are components inside the 18650 cell that remain the same size in the 21700 cell, so…every aspect of the size increase is solely made from the active battery material alone.

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OK, who is driving this?

The Tesla Model-3 EV is reported to be the first vehicle that will use the 21700 cell. Demand from the Model-3 assembly line is assumed to be so comprehensive that it may be a while before the Power-wall devices and other Tesla EV models can start using this new cell from the Gigafactory. As of June of 2017, it has been reported that the Tesla Gigafactory in Nevada is finally in production of the 21700 cell.

The Tesla Model-3

If you haven’t heard of the “Lucid” car company (formerly known as Atieva)…you will soon. They are about to produce an attractive electric sport-sedan in 2018. That may sound optimistic for a start-up that few have heard of, but…they are also the sole supplier for the batteries used in the 2018 Formula-E electric race series. This will be a collaboration between McLaren, Lucid, and Sony, so…this is not vapor-ware…and they are contracted to use Samsung 21700 cells!

The new 2018 Lucid EV

Just like the 18650 cells that these top-5 companies produced before (Panasonic, Sanyo, Sony, Samsung, LG-Chem)…there are cell-models that are optimized for capacity, and also a variation that is adjusted to have the maximum current (high-amps).

You might assume that EV sports cars will be using the performance version of these 21700 cells, but…they use so many cells per vehicle that they can get very high pack-amps from a cell that provides lower amps-per-cell, but…very high capacity.  This benefits all EV’s because…E-motorcycles, E-Scooters, and ebikes will all benefit from these new cells that significantly increase range, while still providing awesome performance. The higher-amp version of these cells (with slightly less capacity), have been spec’d by cordless tool manufacturers (see below). Since we can now have higher capacity or higher amps, from a cell that is only slightly  larger? This is good for all ebikers and ebike manufacturers.

[side note: there are minor issues with every website that provides tech information on any new development. We can either wait until every detail is exhaustively proven, or scan several sources to try and obtain a reasonable opinion based on an average. Exercise caution, but…here is what I found, as of June 2017]

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Panasonic

First up is the Japanese company Panasonic, simply because they are so big…and also because they took the bold move to risk billions of dollars by investing with Tesla and helping to drive all of these new changes. they are producing the 21700 cell for Tesla, but…in the general marketplace, they are claiming to produce the 20700 cell. This is confusing, but…lets roll with it for now…

They are currently offering what they are referring to as their A, B, and C cells. The “A” cell has the highest amps at 30A, the “B” cell has the most range at 4.2-Ah, and then…the 3.5-Ah “C” cell is somewhere between the two, so…they have an option for whatever your priorities are.

30A, 3.1 Ah, NCR20700A

15A, 4.2 Ah, NCR20700B

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Sanyo 

Since Sanyo is now owned by Panasonic, there is a considerable amount of overlap in their product line. The Panasonic “A” cell has the same specs as the Sanyo 20700, sooo…they likely came from the same assembly line, using the same exact design (30A, 3.1-Ah, NCR20700A)

However, whether the PVC heat-shrink plastic-wrap that covers the cell says that it’s a Panasonic or a Sanyo, here is a review from a vape forum:

“…At 30A continuous the temperature rose to 75°C. This is just below the average temperature for a cell being discharged at its continuous discharge rating (CDR) but the datasheet seems to show a higher sensitivity to temperature than our 18650’s so I am not giving it a rating above 30A...”

If you want to run a Bafang BBS02 or a BBSHD at an occasional 30A peak, while using a 14S (52V) battery configuration?…this cell can provide that with only 14 cells. THAT…is amazing (of course, a 1P pack would have extremely short range, but..it can be done)

They can be found here for $10 each, or also…from here for $9 each.

The Panasonic / Sanyo 20700 B

Panasonic calls the NCR20700B a 4.2-Ah cell, and Sanyo calls it a 4.0-Ah cell, but…either way it’s a significant bump over 3.5-Ah 18650 cells. Most “max” range tests drain the cell at a very low amp-rate, but…experienced builders know that the harder you pull the amps, the lower the full range of the cell you will get. This is the truth, regardless of what brand of cell you want, or which vendor you buy from.

HOWEVER!…I think that for these 21700-sized cells, the configuration that will be the most interesting for us is the high-capacity 4.0-4.2 Ah version. This is because…these still have enough amp-producing power to be very useful in the size of packs we need and can fit on our frames. As long as a certain number of cells fit and give us the pack-amps we need…why not go for more range? Trust me when I say that you will not regret buying extra range in your next battery pack…

Here is the review of the Panasonic / Sanyo “B” cell with 4.2-Ah per cell.

“…At 15A continuous the temperature rose to 74°C. This is just a bit below the average temperature of a cell operating at its continuous discharge rating (CDR). This is an indication that we are operating near its true rating…“

Let’s compare a common 14S / 5P battery pack made from 18650 GA cells, and a slightly smaller 14S / 4P pack made from 20700 Panasonic B cells…

52V, 17.5-Ah, 50A, 70 cells (18650 GA)

52V, 16.8-Ah, 60A, 56 cells (20700 B)

This is where the 20700 shines. Any extra length (70mm vs 68mm) just makes the ebike battery packs a hair wider, since most packs place the cells left-to-right, on their sides (from the perspective of a rider sitting on the ebike saddle). The pack will be a negligible 1/12th of an inch wider between your knees, when riding. That leaves only the diameter of the cells to be concerned about.

If you can squeeze-in a 5P 20700 pack, then the small extra height will only be 2mm X 5P = 10mm, roughly half an inch taller and longer than a 5P 18650-cell pack. But…if you couldn’t quite squeeze a 5P pack onto a frame you like, you might be able to fit a smaller 4P pack of 20700’s, while still having 4P X 15A = 60A of power (of course, if you could fit a 5P pack, then 5P X 15A = 75A…not bad!)

Prices will come down in time, but right now you can get the B-cell here for $10 each, and also from here for $8 each. Aaaand here’s another supplier for $8.

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Samsung 21700’s

Samsung is a respected cell supplier from South Korea. They had previously used pouch cells for their large-format EV batteries, but now they have seen the light. Here’s a quote from a review by a vape forum, on the Samsung INR2170030T

“…Its temperature of 78°C at 40A continuous is the average for cells being operated at their rating so I am rating this cell at 40A…”

They also stated that the cell could provide a few seconds of a 60A burst. Not bad for a single 3.0-Ah cell

The Samsung 21700 30T cell.

Here is another review of the 30T cell by a flashlight forum (yes, that is a thing that exists). Samsung has posted that they intend to produce a “47P” cell, and the name implies that it will have a capacity of 4.7-Ah per cell.

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Sony/BMZ

Right now its hard to purchase authentic  Sony VTC cells (which are fantastic). The only way to be 100% certain of getting those without also  getting a few counterfeits mixed-in is to buy cordless tool battery packs and to cut out the cells. So…what has Sony got planned for the new 21700 format? They partnered with the German firm “BMZ” and plan to make the “3Tron” 21700 cell in Karlstein-Großwelzheim, which is near Frankfurt, in central Germany.

BMZ Press Release from 21 September 2016

“…In producing the super cell, BMZ co-operates with the world’s leading cell manufacturer Sony. Its manufacturing expertise with more than 300 million cells annually guarantees top quality. The assembly of the 3Tron batteries will take place at BMZ – Europe’s new gigafactory. With a footprint of 55,000 m², it is Europe’s largest battery factory…“

Sony has announced that it will be a 5.0-Ah capacity. If an 18650 cell can hold 3.5-Ah, it is not crazy to suggest a 5.0-Ah 21700 cell is possible, but that is sounding like it is near the theoretical maximum (using current chemistry and packaging methods), and it is a serious 43% increase in capacity.

XXA, 5.0-Ah, US21700VXX

[I will update this listing when more information becomes available]

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E-One Molicel

Operating out of Maple Ridge, British Columbia, Canada, “E-One Moli Energy (Canada), Limited” is a division of the E-One Moli Energy Corporation of Taiwan. Established in 1987, E-One Moli-Canada is one of the few manufacturing plants producing rechargeable lithium-ion batteries in North America.

E-One Moli has announced that they will also be making a 20700 cell, but they are not posting who (or what) they are making it for. At various times in the past, E-Moli has supplied cells for Zero motorcycles, Milwaukee Tools, and the US military.

35A, 3.0-Ah, INR20700A

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Where to buy them

As usual, any retailer who is willing to sell individual new cells is charging a premium. This is for the global vape and flashlight market. If you want to buy 80-100 cells to make an electric bike battery pack, make sure to contact their customer service, and you might get a better bulk-purchase price.

The blogger “Syonyk” posted that he wanted to acquire some 21700 cells and then he purchased a new DeWalt 20V XR 6.0-Ah cordless tool pack, and gutted it. As of June 2017, Amazon is listing a single DeWalt DCB206 pack for $83, and a “2-pack” for $138. Since we would want a LOT of these cells for the lowest price, lets look at the multi-pack for $138.

Inside the DeWalt DCB206 cordless tool pack.

Pic courtesy of syonyk.blogspot.com, please give him a few clicks, so he will keep doing awesome stuff like this and posting the results. Each one of these packs holds ten of the Panasonic / Sanyo NCR20700A’s, so…30A and 3.0-Ah each. This pack in a 5S / 2P configuration is 18V, 6.0-Ah, and can safely provide 60A! Since its $138 for two, thats $69 for one pack, and brings the cell-price down to $6.90

But, as good as that is (with many retailers demanding $9-$10 each)? in my mind, the best part is that…these come with spot-welded tabs from the factory. If you gently cut the connecting tabs with a thin disc on a dremel, you can solder onto the cut-end of that tab without any heat damage to the cell, like our friend Doctor Bass shows, here. I have read reports that the bus-plates are nickel-plated copper, in order to handle the higher amps.

If you do this, gently lift up the edges of the cut tabs and slide extra insulation between the bare metal tab and the edge of the cell. Remember that the top center nipple is positive, and the entire bottom and sides of the can (all the way up to the shoulder) is all negative. This means the rim under the green wrapper is a charged negative electrode, almost touching the positive tab!

If you want to shop around for other brands of cordless tools (if DeWalt is sold out when you need them), I found this quote on the web:

“Bosch 18V 6.3 Ah EneRacer battery pack uses NCR20700A
Metabo 625343000 18V 3.1 Ah LiHD Battery Pack has 5 NCR20700A’s
Metabo 625341000 18V 6.2 Ah LiHD Battery Pack has 10 NCR20700A’s
Metabo 625344000 36V 6.2 Ah LiHD Battery Pack has 20 NCR20700A’s”

If you want to try this, I’d recommend you buy only one, gut it yourself, and…if it turns out to be what you want, buy as many as you need immediately, before they change anything about the packs you want.

Vape and flashlight suppliers:

IMR batteries dot com, they have the 20700A for $8, and the 20700B for $10 each

Fasttech dot com, they have the 20700A for $9

illumn dot com, they have the 20700B for $10

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Counterfeit Cells are Everywhere!

Only buy name-brand cells from a trusted vendor (Panasonic, Sanyo, Samsung, Sony, LG-Chem). Here is a pic of an “off brand” 18650, but…cut it open and the reason for the tiny capacity is obvious. A small generic cell is hidden inside an 18650 shell. 21700 cells are the hot new item, so…if the price from an anonymous vendor seems too good to be true…

Only buy name-brand cells from a trusted vendor.

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What’s Next for Batteries?

I think as soon as 21700 cells start to become more available, that will put pressure on the 18650 market to lower prices a bit, making the option of an 18650 pack still relevant for the next couple of years. That being said, you are going to be hearing a lot about 21700-format cells in 2018, as the exciting new thing.

I can visualize 18650 and 21700 cells remaining the staple of ebike packs for the next decade, but for E-scooters, E-motorcycles, and large auto EV’s, the big breakthrough I am most waiting for is the Solid State Battery (SSB’s). They currently work in the lab, and the only delay is simply finding the cheapest way to manufacture them. They are scheduled to be in production by 2020.

By making the electrolyte a solid, battery pack volume can be reduced by 1/3rd (if not more). Or, conversely…you can have a battery pack the same size, with roughly 50% more range. The Tesla Model-S is currently rated to have over a 200-mile range, so…having near 300 miles would be pretty amazing.

As far as what possible improvements are doable beyond SSB’s in 2020, I don’t know, but…Tesla has at least eight patents on metal-air batteries. Kinda makes me wonder what they’re up to, right?

Tesla obtains patent for charging metal-air battery technology that could enable longer range

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Written by Ron/spinningmagnets, June 2017

There has been a boom in ebike builders making their own battery packs out of the popular 18650-format cells, and I want to share what I’ve found out about the guts of an 18650, so you will understand more about proper DIY pack-building methods.

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Why would somebody make their own pack?

The existing battery pack vendors will only make (and stock) the packs that they think they will sell enough of. Which means, they will only have packs with certain particular sizes, shapes, and with specific cost-effective cells.

Nobody makes a pack this exact shape and size. If this builder settled on buying a turn-key pack, it would have fewer volts, fewer amps, or both. Pic courtesy of firefighter Barry Morfill, in Shrewsbury, UK.

But…what if you want a pack with a different cell? Or maybe, you desire a very custom shape?  There’s nothing “wrong” with a turn-key battery pack, but…we are under the impression that anyone who is going to go to the trouble and expense of building their own pack, they are likely to also be the type of person who wants high-performance. After all, why go to the expense and trouble of building a low-to-medium performance pack in a conventional shape? They already exist, and they are getting very affordable. (The most-often cited DIY cell spot-welder is about $250!)

This is a graphic from a custom battery building website to determine the maximum number of cells that will fit, pic courtesy of Allex. I think he could have squeezed-in a couple more cells if he had flipped the shock over, so the fat end was at the rear

A third reason (after “custom features”, and using a specific cell), is that if you want to ship a large ebike battery pack internationally, it is very hard right now (and the rules and regulations are likely to get worse over time). If you live in a country where the major ebike battery pack retailers will not ship to you? Then…you can’t get ANY kind of pre-built battery pack. You can still buy all of the components, and build your own, but…buying a completed battery pack is just not available.

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Negative cans and shoulder-shorts

I’m putting this fact about an 18650 cell construction first, because…I still run into people today who are surprised to find this out, and a “short” across the shoulder of an 18650 can will cost you trouble and money. It might ruin an entire expensive pack, and also…IT CAN START A FIRE!

The positive and negative electrodes of an 18650 cell. The only electrical separation is the black plastic seal shown here. YES, the entire sides and bottom of these cells is a conductive metal shell, which forms the negative electrode.

I have seen some caps and shells advertised as stainless steel, but…here is a quote from an 18650 parts supplier:

“The case and cap are both made from nickel-plated A3 steel, and the insulating seal is made from nylon”

Even though it is “possible” to draw current from the negative shoulder of an 18650 cell (so the positive and negative are pulled from the same end of the cell), doing that would also mean you are using the sides of the can as a conductor. The shell is steel, and its conductivity is about 10% of what copper would be, so…it is not unreasonable to call the sides of the 18650 case a “resistor”.

If you are purposefully running current through the sides of the can, it means you are wasting battery watts to heat the shell. Wasted watts and heating the cell on purpose is a bad design. Always pull the negative current from the bottom of the 18650, using something that has better conductivity than steel (aluminum or copper, either raw or nickel-plated).

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The PTC

Just under the cap is the “Positive Temperature Coefficient” device, and it is a thin and compact way to limit the current coming out of an individual cell, when the amount of current is so much that the cell-tip (at the positive end) is getting hot.

The PTC is a conductive washer, but…when it starts to get hot? Its resistance dramatically increases, so that hopefully…less current can pass through it. In this way, it is almost like a re-settable breaker. That brings up the question, how hot does it have to get before it activates?

One seemingly-reliable source states that the current-throttling point begins significant activation at 134C (273F). If that is true for most common cells, I’m not sure what situations exist where the PTC will help…maybe it needs to allow the faulted cell to get “that hot” in order to allow the electrolyte to begin producing gasses, and it is actually the gas pressure build-up which then activates the CID, which provides the safeguard. This same reference states that the PTC returns to full-rated current capabilities when the cell cools back down.

A chart showing how much the resistance of the PTC increases as it gets hotter.

There are several references that indicate a temperature of 60C (140F) is the hottest that any 18650 cell should ever be allowed to get up to (if you want it to last a long time). If you know someone who has gotten their pack hotter than that, and they are proud of the fact that the pack still works, they may not realize that they have thrown away much of their expensive battery packs’ potential life-cycle.

Tesla has an 8-year warranty on their packs, and…they not only designed the pack to never get hot in normal charging and discharging conditions, they also incorporated a pack-cooling system, as did the Chevrolet Volt. The Nissan Leaf was introduced without a liquid-coolant heat-management system for the battery, and they depended on ambient air-cooling, which caused problems that they encountered during the summertime in regions with very hot weather. The Tesla system has a cooling target of 55C (131F), which fits right in with the widely accepted safe max temp of 60C (140F). If they are getting more than eight years out of their battery packs, they are doing something very right.

Also, here is a paper from NASA on PTC devices in cylindrical cells.

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The CID

This stands for “Current Interrupt Device“, and it is a simple and compact device that “pops” when enough pressure has built up inside a cell, and it’s located just below the PTC. There are several variations in the designs. They operate on the same principle, but do it slightly different ways. The only reason any pressure would develop inside  a cell is because some of the electrolyte has converted from a thick gel (almost dry) into a gas, from experiencing too much heat.

If that has happened?… I would not “reset” the CID and try to use the cell again (cells are cheap, and you don’t need to add a risky cell to an expensive pack). The PTC will not reset by itself, but sometimes?…it can be done. I might use such a cell in a flashlight, but not an ebike pack. Wait a minute…actually…I would throw that bitch away. I don’t need my flashlights catching on fire. I have access to plenty of  new 18650’s, and I don’t need to spend even one minute of my life wrestling with an insurance adjuster over a house-fire.

The CID in an 18650 cell. In this pic, the PTC is the dark green washer between the white CID and the red cap (positive electrode). Everything inside the gold insulative gasket is positive, and all the grey stuff outside of it is the negative.

The CID is a thin disc of sheetmetal that is in-between the positive cathode cap, and the rest of the interior of the cell. It has a bowl-shaped depression in the center of it that presses down against another flat metal disc to make contact, and by doing so, that will complete the current-path in normal operations.

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The Scored Burst Disc

Generic cells do NOT have a “burst disc”. If they get hot enough for the electrolyte to begin turning into gasses, and then expand from the building pressure, the cannister will split…somewhere.  If there is a burst disc, it will pop open at that specific location. You should only use name-brand cells from the “big five”, which always have this feature (Panasonic, Samsung, LG, Sony, Sanyo). If they are ever abused in a way where they will burst from internal pressure, the hot electrolyte vapors will always blow towards the burst disc, instead of splitting the sides (sometimes the disc is located on the bottom, sometimes on top…just like my…uh…nevermind).

If the sides split, the heat would be directed towards the cell next to it, and it would make the possibility of a runaway thermal meltdown (and fire) more likely. Here is a paper from NASA on “rupture discs”, if you are interested in this (isn’t everyone?).

Here is a quote from a vendor who sells parts to make 18650’s: “Safety valve will open at 2.8MPa (the valve will open to release interior high pressure if over 2.8MPa, to ensure no explosion from the can)”

Either this cell didn’t have a burst-disc, or…the vents were soldered-over so that any pressure that was building couldn’t blow in the direction the designers intended. Try explaining this to your wife after your house burned down…

Here is a technical paper on thermal runaway events. The most interesting part for me was to see that the copper foil in the “jelly roll” had melted and formed globules, so the interior temperature had to have reached over 1085C (1985F).

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Individual cell-fusing

This section may seem out of place, since this section doesn’t specify anything INSIDE an 18650 cell, but…a big reason I’m even writing this article is to preface the acceptable methods for a home battery pack builder to use, when using 18650 cells [in an upcoming article. Insert link here, when article is published].

This pic below is a close-up from a Tesla electric car pack. The electrodes on the 18650 cells has a fuse-wire connecting each one to a thick nickel-plated copper buss. These wires are connected to the cell tip by using an ultrasonic bonding machine (high-speed vibrations), which cause no heat to penetrate even the upper layer of the cell, much less the electrolyte.

Fuse wire connecting each Panasonic cell to the Tesla’s buss-plate.

Tesla vehicles draw “low amps” from each cell (to ensure long life, and provide long range), so a surprisingly thin wire works fine as the connection to carry the current (in order to get high amps at the motor, they use thousands of them). The tiny diameter of the fuse-wire means that if the car is involved in a wreck and then one (or more) of the cells are shorted, any cell that is flowing high amps will get the fuse-wire hot enough that…the fuse melts very quickly.

An internal short of a cell is extremely unlikely, but…whatever the reason for high amps in the cell, heat from high amps will melt the fuse-wire, which will separate that particular cell from the pack. One of the Tesla models has 74 cells in each paralleled group, so…if one cell pops its fuse? that P-group will be just fine running on the remaining 73 cells.

There are quite a few youtube videos about taking some cheap salvaged low-mileage 18650 cells and building them into an off-grid home-electricity-storage system. Fusing is less needed in a stationary system (no crashes into other homes), but…it can be an easy and cheap feature to add to your design, whether it is for a home or a vehicle.

If you read farther below, you will see that I do NOT recommend soldering onto the negative anode of the cell (the flat bottom), but…I actually believe that…with the right tools and techniques? Soldering a fuse-wire onto the positive cathode is very easy and quite safe, with almost no risk of damaging the cell from overheating it.

Prep the surfaces, apply some solder-paste, set the fuse wire where you want it, and press down for a second with a fat-tip 100W soldering iron. Or, use a resistance soldering rig, which I will write about soon. If you have a spot-welder? Fuse-wire can be spot-welded onto any 18650 positive terminal.

If you want to use fuse-wire on your design, maybe consider flattening the tip of the fuse-wire to improve the contact area onto the positive 18650 electrode nipple. In order to get a consistent thickness on the fuse-wire tip, maybe put some steel sheet-metal on either side of the fuse-wire tip, and then you whack it with a hammer. That way, the wire tip-thickness will be very consistent. The sheet-metal that determines the thickness of the whacked-wire tip should be roughly about “half-to-one-third” the diameter of the round cross-section of solid wire.

Here’s an example of using fuse wire with solder, on a DIY home battery storage pack.

Individual cell-fusing doesn’t have anything to do with the internals of the 18650 cells, but…they are a safety feature that is easy and cheap for anyone to add to an 18650-cell pack. If you look back over the info above on how the positive end of a cell is internally constructed, you can see that the positive electrode end can take some heat without being damaged.

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A “Protected” cell circuit

Ebike battery packs are made from UN-protected cells, because the BMS and controller decide how many amps you will be drawing from them. I’m adding this section to this article because…the pictures in some web-catalogs do not show why protected cells are different. If you are buying cells to build an ebike pack, make sure you do not order the ones with these protection circuits.

A protection circuit on an 18650 cell, intended for a product that does not have any current-limiting.

Protected cells are also a little longer than an 18650 that has no protection circuit. This current-limiter is attached to the negative electrode, and then the current passes through a very thin conductive ribbon up the side of the can to the positive electrode (ribbon shown in the pic above). That ribbon is typically then attached to the underside of a false cap that “snaps on” over the factory positive electrode cap.

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Flat top vs button top

Some flashlights (or other commercial devices) have a hollow cylindrical protrusion inside it where the cells’ positive cathode tip presses against the housing contact that the 18650 is inserted into. This prevents the cells’ negative electrode from making any contact, if the cell is inserted backwards by a drunk customer (who you lookin’ at? I’m not talkin’ about me…*breaks down and sobs uncontrollably “Why did you leave me?…WHY?” ).

That protective socket-shape means that a raw 18650 cell cathode will also not make any contact, even if it is inserted in the proper orientation. For those devices, you must order a “button top” cell. It has an additional “snap-on” cap that is narrower and protrudes farther out. This also makes the button-top 18650 a  little longer, and you should not order these when building an ebike pack.

18650 flat top vs button top. Ebikes use the flat-top cells.

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The Jelly Roll

If you want to cut open an 18650 cell, then first… you must fully discharge it for safety. One way is to hook it up to any incandescent filament bulb, such as a 12V automobile tail-light bulb. A 12V LED will not work, because they require a fairly exact voltage to work. Also, a very large bulb (like an old headlight) might allow so much current that the cell overheats, so…a small incandescent bulb is safer.

Of course, that also means that when using a small incandescent bulb, the cell will take longer to discharge. When you no longer see any dim light coming from the filament, I have even read about putting the cell in a bucket of water with a spoonful of table salt (overnight), to ensure that it is absolutely 100% drained.

To cut open the metal can of an 18650, I recommend a Dremel with a thin abrasive disc, instead of a tubing cutter. Those tubing-cutters cause an indentation on the edge of the cut, making a removal of the jelly-roll difficult. Once you get the jelly-roll out and begin to unroll it, you will notice there is a copper foil as a base for the anode chemicals, and aluminum foil as a base for the cathode chemicals.

Discharge the cell completely, use gloves and eye protection, and do this in a well-ventilated area. Plus…wait until your wife is not home, and don’t tell your mommy.

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Inside the bottom of the can, the Anode

Once you cut the can open, you can see that the only thing between the jelly-roll and the bottom of the metal can (that forms the bottom and sides of the 18650) is a thin plastic insulation washer.

One of the most important things I want to get across in this article is that when you are assembling a bunch of cells into a pack, it is the negative anode (the sides and bottom) that are the most sensitive to heat.

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How is the whole enchilada stacked up?

Here’s a couple of images that I thought would help to get my points across. They are from the official patent of a Samsung 18650 cell. The top of the cell has all those pieces stacked up above the electrolyte in the jelly-roll, but the bottom? It only has that one thin plastic washer…good old #11.

Samsung patent “US 20090117451 A1”

If you’ve read this far, here is another paper on 18650 cell construction and safety from Dr Wesselmark, who holds a PhD in Applied Electrochemistry from the Royal Institute of Technology, Stockholm…co-written by Tom O’Hara, who has over twenty years R&D experience with Energizer battery.

If Dr Wesselmark or Tom reads this? I owe you a beer, just like Niels Bohr.

Thanks for reading, and send any additional info, suggestions, or death threats to: Prisoner #41, Kansas state correctional facility for the mentally unstable.

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Written by Ron/spinningmagnets, July 2017

The NYX frame kit uses carbon fiber in the construction of the main frame battery compartment, and using this light and strong material makes this frame a rare and upscale product.

Eloi Fugere and Cedrick Baker

The NYX company is based in Drummondville, which is located in Quebec, Canada. The concept of an upscale electric bike frame kit using carbon fiber was finally put into action by the NYX company founders, Eloi Fugere and Cedrick Baker. Eloi remains as the head of NYX, but Cedrick has moved on to other ventures.

Cedrick Baker on the left, and Eloi Fugere on the right.

The ebike in the pic below is a snapshot of a typical NYX build. The frame “can” be used for a street ebike, but the vast majority are currently used for an off-road build, and this one uses knobbie tires that are mounted on very strong moped rims. This example is outfitted with high-end brakes, and a well-regarded fork-set.

The rear hubmotor is a common size, using a 205mm diameter stator. If you look close, you can see the radial aluminum fins that have been added to help the motor shed heat better, and…although you can’t see it, the inside of the motor has a sample of Ferro-Fluid in it to further improve the heat-shedding. Don’t let the mirror, headlight, and fenders fool you…this ebike is VERY illegal on city streets due to the “over the top” power level.

A snapshot of a typical NYX build, courtesy of ES builder ‘Merlin’

Several different controllers have been tried, and the Adaptto Max-E from Russia appears to be a NYX-builder favorite…just like the one shown here.

Battery Box

There are several frame-kits available that have a large “boxy” section in the frame in order to hold a large battery, such as the Qulbix, the Phasor, the Greyborg, and also the Vector (among others). You can always have a smaller battery inside in order to keep the ebike as light as possible, but…I immediately wondered…exactly how large of a battery could fit?

After some searching, I found a build that was using two rectangular blocks of cells that formed a 20S / 12P battery pack (240 cells in the 18650-format). The nominal (average) voltage of lithium 18650 cells is 3.7V, so 20 of them in series is a 74V system (It’s 82V when fully charged to our recommended maximum of 4.1V per cell).

Pic courtesy of ES member ‘ridethelightning’

Now that we know the voltage, the total power in watts is that number multiplied by the amps. The cell this builder chose is the highly-regarded Sony VTC4. Each cell has 2100-mAh of range, and a 12P pack results in a fairly large 25.2-Ah pack. Since this cell is factory rated at 15A per cell, a 12P pack also means it should easily produce peaks of (12P X 15A =) 180A!

74V X 180A = an eye-opening 13,000W

The NYX battery box opening is on the top

The NYX battery box is formed by bonding the two side halves together. That’s not just the most cost-effective way to make a box this size, it’s also a great way to make a very light structure that still has great performance. The heavy loads from a hard hit when taking big jumps will focus a lot of stress along the side-panels. If the battery access opening was on the side, then the removable cover would have to be strongly re-enforced to handle it, which would add weight.

The more consistent and rigid that the side-panels are…the less stress the top-panel feels.

Concentric Bottom Bracket and Pivot

There are actually two distinctive features of the NYX frame. After the eye-catching carbon fiber, the swingarm pivot is concentric (having the same centers) with the bottom bracket.

Most off-road ebikes have the swingarm pivot located nearby the bottom bracket, usually a little above it, to reduce a reaction called “squat” when high power is applied. However, since the swingarm pivot and the Bottom Bracket centers are in different locations, the chain path must change as the suspension moves up and down, sometimes resulting in a reaction called “chain growth”. Even in ebikes that don’t have a derailleur (such as a single speed system), the chain is usually sized a little longer, and then the varying chain-run length will have it’s slack taken-up with a “chain tensioner”

The NYX concentric bottom Bracket and swingarm pivot. Pic courtesy of ES member brum brum, from Wales, in the UK

The Greyborg also uses a concentric bottom bracket, so…both of these frames never experience any chain growth. This means that…as soon as you move the wheel axle back enough to tension the chain, you can just set it and forget it…with no slack-tensioner needed.

Another ebike that is known for this feature is the Stealth Bomber.

In the pic below, our friend Luke chose a belt instead of a chain, which runs very quietly. This is one of the benefits of a hubmotor, even in a time when so many are switching their off-road builds to a mid-drive. A direct drive hubmotor that is driven by a sine-wave controller, and then combined with a belt-drive from the pedals? That is about as quiet when running as physics will allow. The loudest noise will be the sound of the tires rolling across the ground.

Luke’s NYX, with a huge QS-273 hubmotor, Schlumpf pedal-drive, and Gates belt.

He also added a top-of-the-line Schlumpf drive crank-set. This allows him to use a smaller pulley in order to retain a good amount of ground clearance, while still being able to pedal along at the higher speeds, due to its 2.5:1 gearing.

If the picture above looks a little “off”…it might be because of the proportions of the motor. It is a QS 273, which is extra large, and extra powerful. A common 205mm diameter stator is more than enough for my wildest dreams, but…Luke wanted just a little bit more.

A NYX in the Garden

Here are a few pics of a NYX build that show how pretty it is, when you finally get up close. Pics courtesy of ES member ‘Grunt’.

A NYX framed ebike in the garden

The controller dash panel is from a Russian “Adaptto Max-E”.

The battery pack access panel

Below, you can see that, rather than make the battery box shorter and fatter to have more battery space, NYX opted to make it narrow and taller. The interior dimensions easily fit 18650 cells on their sides, laying left to right.

This angle shows how narrow the NYX battery box is.

Dr Bass, 2WD, and MXUS

Dr Bass has been a famous ebike hot-rodder for years, and he was an early promoter of high-performance ebikes. Since he is from Canada, he was one of the first early adopters of building with a NYX frame, except…he went in a slightly different direction.

If you look closely, you will see that his NYX below is using street tires, and that is the main clue to why he went to 2WD. The desire to make a 2WD ebike for off-road is an obvious choice, but for the street?…Dr Bass knew from “hands on” experience that when you build something with VERY high power, you can quickly reach a point where traction becomes the limiting factor. Doing a burnout with the rear tire can be fun…maybe a few times, but…after while you begin to realize that spinning your rear tire…is not the same as accelerating.

The Dr Bass 2WD NYX build

Dr Bass has been improving his 1/4-mile acceleration times with each upgrade. Although I normally recommend a geared hubmotor for the front motor of a 2WD build, Dr Bass knew he was going to be pumping a lot of heat into his motors, and he decided to use large direct drive hubmotors from MXUS on both axles, along with drilling ventilation holes into the sideplates to let the heat out.

Dr Bass’s 2WD NYX ebike doesn’t have a lot of range or a heavy battery…he only needs it to travel 1/4-mile at a time (*wink).

LINKS

For more information about NYX…

Here is their home website

Here is their Facebook Page

Here is their youtube channel

And…if you want a pre-built ebike instead of building up your own, NYX now has several turn-key ebike models available

Written by Ron/spinningmagnets, May 2018

Over the last year, I would occasionally hear about these new Mobipus controllers. Once a few hot-rodders I know got their hands on one and then said they were great, I knew I had to take some time to look a little deeper at what all the fuss is about.

Most of the hot rod controllers that are found on powerful ebikes are actually designed for small motorcycles, so this is just another variation of that theme (the pic on the header above is Sketch Coleman in Australia, showing off on his Mobipus-controlled electric conversion Super-moto…more on that later).

Shenta Tsai, the designer

I’ll get to the reasons that some builders like these, but first I’d like to tell a little bit about the engineer who designed them. Shenta is from Taiwan, and his family has a large business with manufacturing facilities in Thailand. Somewhere along the line, Shenta became fascinated with electric vehicles, and began hot-rodding them to learn first-hand how they could be made to run fast.

Shenta Tsai, designer of the Mobipus family of controllers

Hot-rodding a motorcycle is not cheap, but…it is MUCH cheaper than hot rodding a car. I can sympathise because I got my motorcycle license in 1978, and I have experienced first-hand how a medium-weight motorcycle can easily beat some impressive cars from stoplight to stoplight (and yes, speeding tickets are expensive). Shenta chose a common motorcycle found in Taiwan to hot rod (an E-Grom, click here), and he used it as his prototype for experimenting.

“…My bike, the Red Devil…goes from 0–100 km/h in just 3.6 seconds…” [100km/h is 62-MPH]…24S LiFePO4 (100V) 60-Ah pack, range good up to 90-km on eco, 60-km on normal. These motors are super hard to get, not from QS…I got my own magnets and send them to 9C for assembly…

...The concept of the company is built around a very simple idea and philosophy: I just want to make great products to fuel our passion, and share it with people I like. Fuck commercial products made for profit only. I ask myself, am I pleased with this; would I pay for it?…

…Never ask what your clients’ needs are because if your standards are higher, you’ve got to satisfy yourself first. My idea is simple: we don’t look for ready-made solutions, we don’t buy other people’s know-how. We go from not knowing, to knowing. I ask, am I pleased with this? That is always our starting point and ending point. Right now we are also working on developing a new BMS….”

I’ve never met Shenta, and I already like this guy.

What’s the competition for Mobipus?

If Mobipus was primarily focused on electric motorcycles and scooters (which are a very popular transportation vehicle all around the world), why are we talking about them in an electric BICYCLE web-magazine? Well, they have two models that are small enough to be considered appropriate for hot rod ebikes. And yeah…they are expensive.

A resident hot rodding guru from Canada at the endless-sphere forum is named Stephane Melancon (Doctor Bass). Recently, he has been a fan of the Adaptto controllers from Russia. I “almost” researched and wrote about them a few times, but there was always something else that was pushed to the front of the line.

In the meantime, the Adaptto company has had some issues. Every design has some pluses and minuses, and Adaptto controllers have some desirable features, but…they have also had spotty customer service, and they refuse to increase production, so they will remain hard to get for the time being. Even their fans have admitted that they are somewhat difficult to program, and programming a controller to work well with a specific motor is vital in order to get the best performance.

The other controller I have read as a competitor to Mobipus is Sabvoton, a Chinese maker of scooter controllers. In spite of a strong fan-base, Sabvoton controllers are fairly large for the same output, compared to Mobipus, and space on an ebike is a major consideration. Also, Sabvoton controllers have only one shunt, and Mobipus controllers have three…which I will explain below.

The 48070 and the 72200

The “Weichayan” 48070 (click here) is their 13S / 14S controller (13/14 cells in Series), which will run a 48V or 52V system using 35A continuous and 70A as a temporary peak. When under hard acceleration, that is 3600W of power.

The size is 120mm X 120mm, and 65mm thick (4.8 X 4.8, and 2.6 inches thick). I haven’t found anyone yet who has been using the 48070, but I think it would work well with the 1500W-rated direct-drive hubmotors with 35mm wide stators, which perform well with 3600W peak power (and they are my favorite size for a daily-commuter DD hubmotor ebike, or cargobike)

The Mobipus 48070

They also have a slightly larger 48150 model (48V 150A, click here), but I haven’t found a retailer for it yet, and they may soon be available direct from Mobipus.

The “Spiritrum” 72150 (72V 150A, click here) is roughly the same size as the 48150, and it is much more powerful. It can be programmed to run anything from 48V up to 72V (13S, 14S, 16S, 20S…which is a nominal 48V, 52V, 60V, 72V). The max volts are listed as 90V, but a 20S pack that is at a nominal (average) voltage of 3.6V per cell, is actually 4.2V per cell when fully charged, which would be (20S X 4.2V =) 84V.

The compact Mobipus 72200 with a large aluminum finned “heat sink” attached to help cooling

If you raise the voltage on your project higher (96V instead of 72V), you can get the same total power with fewer amps, which “can” allow the system to run a little cooler. However, higher volts are more dangerous to work on, plus the components for higher volts are less efficient. Lower-efficiency components will turn more of the input-watts into waste-heat instead of wheel-power. The Australian retailer I found has special-ordered the Spiritrum model as a 72200, using 72V and 200A (phase amps are limited to a max of 350A).

If you are wondering what the Red Devil uses, it is the 72600 model modded to allow 100V, which runs 100V 600A for about 60,000W (you can see a performance video of the Red Devil by clicking here). Now that very high-amp cells are readily available, many hot-rodders are experimenting with 72V systems, because the efficiency is much better, and the 20S battery packs are simpler and slightly smaller than a 24S pack.

Sketch Coleman (in the header pic above) is using the Mobipus 72600, and a video of that can be found by clicking here…

Waterproofing

One of the features of all the Mobipus controllers is the extreme water-proofing. They are fully potted, and click here for a video showing a running motor test while the controller is bathed in water. All controllers and throttles should be made like this.

A Mobipus controller test of water-proofing

Sam’s rotary throttle converter

Most electric bikes use a Hall-sensor based hand-throttle, but few high-end builders actually like the feel of the common ebike throttles. Motorcycles are a HUGE global market and competition has resulted in a wide variety of affordable mechanical cable-throttles, but if you try to use one of those, you need something to convert the cable movement into an electrical signal.

Sam is stocking the best mechanical-to-electrical throttle converter he has found. Not only does this allow the builder to use a readily-available motorcycle hand-throttle with an excellent “feel”, it also adds an extreme level of water-proofing, since the electrical portion can be tucked away inside a water-proof housing around the controller.

Sam’s motorcycle throttle to electrical converter

The Dashboard

One of the really great things about the Mobipus system is the dashboard. Instead of designing a proprietary display that you can only buy from Mobipus, the system is designed to accept any windows device as a display. This means your display can be a s small as a smart-phone, or as large as any readily available windows tablet device. Since you wouldn’t be using the display for its computing power, you can even buy a used one to save quite a bit on the price.

The Mobipus display

More Features

The Mobipus uses true sine-wave control for a motor operation that is as smooth and quiet as is possible.

It has an adjustable regenerative braking feature (called regen), which converts a motor into a magnetic brake while slowing down. Many people seem to be excited about how a few watts are pumped back into the battery by regen, but the amount is very small. Using regen as a brake is a feature that I am finding is extremely popular once anyone tries it.

It also uses what’s called Field Oriented Control  (FOC), which requires the controller to measure the current in each of the three motor phase cables. This is why it has three shunts instead of only one. A shunt is a conductor that has a very precisely-measured amount of resistance, so the controller can measure how much current is passing through that particular cable by calculating the very minor voltage drop across its length during operation.

Ballarat Ebikes in Australia

Sam Dekok runs Ballarat Electric Bikes, which is close to Melbourne in Australia. So far, he is the only dealer I’ve found for Mobipus controllers. English is his native language, and if you don’t want to program your Mobipus controller, Sam learned everything about the Mobipus programming, so he can program it for you.

He can even change the program after you have it, by remotely accessing it if you hook it up to your internet-enabled laptop (for a fee). Be aware that one of the things that customers have really liked is how easy and intuitive the programming. Shenta hated how hard all of those other controllers were to program, when he was experimenting with all of the other options.

Sam has been a hot-rod ebike enthusiast for many years, and his day-job is building hybrid vehicles for the Australian government. His youtube channel has one video that is comparing the Mobipus 72200 and the 72600 (click here), and his other videos are in an index, found here.

Sam currently stocks the 72200, and also the 72600, which he feels will be the most popular. The 600A version is roughly twice as large as the 200A, and that one is really only suitable for an electric motorcycle.

Ohbse in New Zealand

The endless-sphere forum has a member from New Zealand, who calls himself Ohbse. Here is what he has posted about his Mobius build.

“…When compared to the common Sabvoton 72V 150A controller it’s very favorable, less than half the volume, less weight, more power, much better software, better support, more safety and features. Superior connectors, better build quality and comparable price, though much cheaper than the Adaptto or Kelly options.

I’m now running a 72200 on my DH Comp with a QS 205 50 V3 3.5T in a set of 17″ wheels with Heidenau K56 tires, 20S / 12P of Samsung 30Q cells for about 2.5-kWh. Currently configured to about 300A phase/180A battery and it really hauls ass, while being exceptionally controllable…”

A Mobipus-controlled ebike from New Zealand

Jim McPherson’s off-roader

I’ve reached out to Jim McPherson, who has posted a video of his high-powered Mobius-controlled off-road ebike on youtube. I am hopeful he will respond, so I can find out more information about it.

Mobipus has posted on endless-sphere, and that discussion thread can be found by clicking here.

The link they provided indicated you can info direct from the customer service by emailing Danny@Mobipus.com

Written by Ron/spinningmagnets, November 2018

The TS in TSDZ2 stands for Tong Sheng, and that company decided a few years ago to make a mid drive kit that was as small as possible, but it would still be able to meet the 500W power restrictions of Canada, Austria, and Switzerland. Electric bike experimenters have figured out that it can actually put out an occasional peak of 750W, and it’s growing popularity has caught my attention. Here’s what I could find out about it…

The tiny mid drive with torque sensing

How small is this small mid drive? take a look at the pics below. From the right side it is almost completely hidden behind the large chainring (and trust me you will want a largish chainring). And from the left side you can see that the only place to put it is below the bottom bracket (BB, the pedal-spindle assembly).

The TDSZ2 on a Dutch-style upright commuter frame.

The TSDZ2 from the left side. If you try to rotate the body forwards and up, the squarish controller cover would protrude downwards more. This location is where it’s designed to be.

Europe really likes what’s called “pedal assist”, meaning an electric bike over there is typically NOT set up to use a hand throttle. When you pedal, the power is applied. And when you stop pedaling, the power stops. They have a “street legal”  speed limit on ebikes of about 16-MPH (25 km/h). You can go faster if you want, but…over 16-MPH, you can’t add any electric power.

The USA has a 20-MPH speed limit for ebikes on streets, and the power limit is 750W (one horse-power). I don’t want to get off on a rant, but it’s illegal in the USA to ride on the sidewalks, and the slowest side-street speed limit is 25-MPH, so…if an ebike commuter wants to share the road with 4,000-lb steel death-machines that are operated by texting zombie-drivers, we have to back-up the traffic with our puny 20-MPH legal ebikes.

To be fair, as long as you keep it under 100-lb, you can get your ebike licensed and insured as a 45-MPH moped, which grants you the right to ride in traffic with tons of horsepower. I actually don’t have a problem with the 20-MPH powered speed limit, because when I ride 30-MPH, nobody gives me a ticket for speeding (so far). But I have  a big issue with the power limit. Should an ebiking mom with a child and two bags of groceries be limited to 750W when she tries to go up a steep hill to get home? Should she walk, or just take a car? [rant over]

Getting back to Pedal Assist Sensors (PAS)…there are two main types. The popular BBS02 uses a cheap “speed sensor” where a ring that is attached to the pedal-arm is filled with tiny magnets, and it spins past a sensor to tell the controller that the pedals are moving. It’s popular because it works “well enough”, and it helps to keep the price down.

The other style (the more expensive one) is called a “torque sensor” (TS). There is one TS style that is built into a bottom-bracket spindle to activate a hubmotor. And there is even a TS style that monitors the tension on the chain.

The TSDZ2 torque-and-speed sensing bottom bracket assembly. The strain gauge in located in the center of the spindle, and the two discs on the left (one stationary, one spinning) comprise the speed sensor.

One of the things that experimenters like about the TSDZ2 is that it has both, a torque sensor and speed sensing. A “strain gauge” is a tiny but sophisticated device that measures the strain that occurs in a metal object, as force is applied to it. An ebike torque-sensor is a specialized type of strain gauge.

I’m mentioning a lot about torque-sensors because many ebikers like it…and some like it a LOT. I have ridden many factory ebikes with TS, and I appreciate its virtues. The power application is instantly on, and when you stop pedaling, it is instantly off. One key feature is that the harder you pedal, the more power it applies, with a very smooth transition.

PAS power levels are adjustable, regardless of the type. TS enthusiasts often mention that it is a more natural and intuitive cycling experience to use a TS type of PAS. The expensive factory drives from Bosch, Yamaha, and Continental use this. But those companies won’t sell it in a kit that can be added to a frame that you already own. There are only a few companies that will sell a TS kit (Lingbei, Xofo, etc), and the TSDZ2 is not only the most available, it is also the most popular.

If you are annoyed by a speed-sensing ebike with it’s “delayed power on, and delayed off”, the time interval can be adjusted, but…like most people, I am not concerned about it. My favorite ebike has a 1500W BBSHD. It takes a 1/4 turn of the pedals to start power (or I can start with the hand-throttle), and after I stop pedaling, it takes a second for power to stop. I spoke to some people from Bafang, and they actually feel that the delay is a safety feature. If power is instantly on from a slight pedal movement, the bike could jump when you don’t want it to, or someone simply bumps into the pedals when you are at a standstill.

36V, or 48V?

I had stumbled across the TDSZ2 a few years ago, but at 36V and being adjustable to 250W-500W, I wasn’t interested in it, and there was always something more interesting to write about at the time. Well, one of the quirks of the TSDZ2 is that the controller is a  mass-produced unit by Kunteng/KT, and it uses a programmable master chip that is unpotted (not sealed under a thick coating of water-proofing goop). That makes the programming easy to hack (more on that below).

When I was un-impressed by the TSDZ2 years ago, it was a 36V unit that had a max adjustability of 500W, which means it was clearly designed for all the nations outside of the USA (admittedly a huge market), but if you start using this unit at 48V, I’m told it really wakes up (33% more watts, without a significant increase of heat).

Now, it’s finally time to address the elephant in the room, which is the TSDZ2’s biggest competition. The Bafang BBS02 (the BBS01 uses 36V, the BBS02 uses 48V/52V).

Both of these mid drives have a poor heat-shedding path from the hot stator to the outer aluminum shell, so it is typically better to hot rod them by increasing the volts instead of the “heat producing” amps. That being said, the “750W” BBS02 has a better heat-shedding path, and also it starts out with more copper mass in the motor.

If you add a temperature sensor and follow the rules of wise mid-drive operations, the BBS02 is regularly run at (52V X 20A =) 1100W. To be clear, the TSDZ2 is maxed-out at 48V X 18A = 860W (I recommend 52V X 16A, plus a temp sensor). If you are one of those people who wants to obey the law, even though you live in a land where the police don’t know how to read a multimeter, I recommend 52V X 14A for a true 750W. The fewer amps you use, the cooler it will run. If you rarely end up using the highest power settings, you should lower the max amps to reduce the motor heat.

For people in Europe, part of the appeal is that Tong Sheng actually makes a street-legal 250W drive using the same body, so this tiny 750W motor looks legal. Did I mention that it’s tiny? I’ve seen coffee cups that were larger (and daddy likes his coffee).

The controller will likely overheat at any amp level above 18A, so the path to the max power is using more volts. Plus, a 48V battery can power an inverter to provide 120V AC to your home during a power outage. A 36V battery cannot. Most home back-up inverters will accept 48V/52V (13S/14S), so…the 48V/52V batteries are my favorite.

Let’s open it up!

I have occasionally wanted to write a certain article, but if I couldn’t find any pics, there would be no article. By the time I finally became somewhat curious about the TSDZ2, there are now plenty of user-posted pics to add.

Here is a 23-minute video of tearing down a TSDZ2 (click here).

A TSDZ2 upside down, and ready for surgery

The infamous TSDZ2 side-cover

The Tong Sheng TSDZ2 has a water-proof rating of IP54, which is pretty good. Notice that the side-cover above has a rubber O-ring around its’ edge. I would also recommend spraying the controller with a conformal coating, and then drilling a tiny 1/8th inch diameter hole at the center-bottom of the cover to allow any condensed humidity to drip out (instead of building up).

The TSDZ2 left-side guts with the side-cover pulled off.

The three larger 16-ga Blue/Green/Yellow (BGY) wires above are the motor phase wires (18A max). The five smaller wires that are attached to the white plug, they are for the Hall sensors. The red and black Hall wires are the positive and negative for all three Hall sensors (5V), and the thin BGY wires are for the on/off signal from the three Hall sensors to the controller.

As you can ALSO see…there are many layers between the hot stator and the aluminum shell, and not enough contact between them to help absorb the peak heat, and then shed it to the outside air. This runs fine on 500W, but 750W requires caution.

The TSDZ2 motor, and the primary 4.5:1 reduction

The helical gears shown above (spirally shaped teeth), are more expensive than straight-cut “spur” teeth, but…they run quieter at high RPMs. The blue plastic reduction gear also acts a a “mechanical fuse” so that…if someone applies too much power? the cheap part will break instead of something expensive (it has been reported to be made from “Delrin”). Also be aware that it is not just the “applied power” that is a concern, the heat that you cause can make the blue plastic gear softer, which lowers it’s power rating.

The blue gear has 36T, and the metal drive gear has 8T, for a 4.5:1 reduction in RPM’s, and a 4.5:1 increase of torque at the output of the blue gear.

The TSDZ2 motor

The TSDZ2 uses a 3-phase Permanent Magnet/PM in-runner motor, 18 poles on the stator (3-phase, so 6 poles per phase), 16 poles on the rotor (8 pole-pairs). You can read our article on the how and why of motor design by clicking here

The TSDZ2 controller

Now…let’s move on the the chain side

The 30 CSK-P Sprag clutch from the TSDZ2

With the clutch-bearing types found on a bicycle, the shaft can spin freely in one direction, but…then when it spins the other way, the shaft “grabs” the outer bearing-shell, and they both spin together. The three most common styles are a sprag, ramped-roller, and pawl.

For a 10-minute video on how to swap-out the sprag clutch, click here.

From left-to-right. A sprag clutch, a ramped-roller clutch, and a freehub pawl-set which is used on common cassette bicycles. The TSDZ2 uses a silent sprag clutch.

The secondary has a 93T gear being driven by an 10T, so it is an 9.3:1 reduction (the primary “blue gear” was 4.5:1), for a total of 4.5 X 9.3 = 41.8:1 reduction between the 4,000-RPM motor and the pedals. Having a very high reduction like this allows a fairly modest motor to put out a decent amount of torque.

The TSDZ2 secondary RPM reduction

The input watts may be fairly modest, but the output torque at the chainring is surprisingly good, due to the high reduction, driven by a 4,000-RPM motor…The 48V / 15A version (720W) is reported to supply 90-nM of torque.

The noisy brass “upgrade” gear, the HF1216 “ramped roller” clutch-bearing from inside the primary gear using needle-rollers, and the 609RS shaft bearing.

If you hot rod a TSDZ2, there are many parts that could be damaged by the added heat, but…as far as the mechanical limits, the three main culprits are shown in the pic above. If the blue plastic gear is damaged, you can replace it with a readily available brass gear, however…the drive WILL be noticeably louder after that.

Inside that primary reduction gear is a roller-clutch bearing (shown in the middle of the pic above). The stock 500W unit is made from “Chinesium”, which is a blend of recycled Chinese scrap steel and expired South-Korean cheese. If it dies, replace them with very affordable units from Japan or Germany…

Here is a video from an Italian website that shows how to replace the blue nylon reduction gear with a brass upgrade gear.

110-BCD and two chainrings

The TSDZ2 comes with one 42T chainring, which uses a fairly common 110-BCD mounting pattern (110mm, Bolt Center Diameter ). However, due to its’ modest power level, some builders are been very appreciative that this style is easily adaptable to using two chainrings and a derailleur.

I honestly believe that anyone who uses 750W (or more) will eventually realize that they can be happy with the simplicity of a single chainring with no derailleur, but…some builders still want this, and the TSDZ2 is one of the few mid drives that allow that.

A TSDZ2 that has been adapted to using two 110-BCD chainrings and a derailleur, shown here on a recumbent tadpole trike.

If you don’t want to hack the controller firmware (which voids the warranty, see below), the stock unit comes with a 90-RPM power cutoff. This is why I mentioned earlier that you may actually want a large chainring. When the pedals reach 90-RPM, the power stops, so a larger chainring raises the road-speed where the motor-power will still be applied.

When a customer is programming it, you have to tell the controller about the diameter of the tire (so the speedometer will be accurate), and a frequently used trick is to tell the controller that you have a 20-inch tire, so it will provide power at a much higher RPM compared to when using a 26-inch tire. Since this unit measures the RPMs of the pedal-spindle, you can also change the chainring tooth-count to bypass some of the embedded stock power-at-speed limitations (these “hacks” mean that the stock speedometer will not be accurate).

The stock single chainring has 42T. Using a 42T on the front will provide about 28-MPH when using an 11T rear sprocket on a 27.5-inch tire, when using an unrestricted controller. I am firmly against ANY power limits, but I do believe that the current 28-MPH (45 km/h) federal speed limit for ebikes in the USA is actually very reasonable.

Here’s a Review…

“…I prefer the Tongsheng and here’s why: It’s much smoother and blends into the normal bike riding experience, but still giving a nice boost. Although the Bafang is more powerful, it’s more like riding a moped and not as intuitive. With the BBS02, you just spin the pedals and go. With the TDSZ2 you have to apply pressure to the pedals and so it feels more natural. That said, I highly recommend both, but I prefer the TSDZ2. 

Power: The BBS02 delivers 100% power as soon as you start rotating the pedals. It can be too much power if you have it on a high setting. The BBS02 can be set on levels 1-to-9. I typically kept mine on 4. It’s only when I wanted turbo speed that I increased it to 9. I found that I frequently adjusted the power levels, like gears, so I could keep it in control. If I had it on a high level, it could lurch unexpectedly.

The TSDZ2, on the other hand, is torque-sensitive, so it detects how much pressure is put on the pedals and delivers more power the harder you pedal. The TSDZ2 delivers the power more smoothly, so I never feel the need to adjust the levels. The second I reduce pressure on the pedals, the motor slows down. The TSDZ2 has 4 levels. I usually leave mine on 3 and just forget about it.

The BBS02 can be programmed using a special cable to adjust how quickly it reacts to pedal inputs. Some people insist this improves the performance and smoothness, but I haven’t tried this.

Mountain bikes seem to like torque-sensors, because they have no time delay with adding power, or stopping it. They also like a light drive, and this kit is about as light as a 750W mid drive could be made.

Brakes: With the BBS02, I often used the e-brakes to cutoff the motor. I would often gently squeeze the brakes, even if I was still pedaling, if I’m going near traffic or pedestrians. Then I would release the brakes and the motor would re-engage. You don’t really need e-brakes with the TSDZ2. I would just pedal more lightly and the motor turns off. It’s more intuitive. In fact, I re-installed my regular brakes instead of using e-brakes (bonus: less wires). There is no fear of lurching. It’s just smoother. Most TSDZ2 kits don’t come with e-brakes or a throttle, and you don’t really need it.

Gear sensor: Also, I purchased and installed a gear sensor for the BBS02. Changing gears under power can cause them to grind and get damaged. The gear sensor temporarily cuts off the motor as the gears change. The TSDZ2 doesn’t have this option, but, again, it doesn’t seem to need it. The motor cuts off very quickly when you stop pedaling or reduce pressure on the pedals. It’s like how it works normally on a bike. 

Speed: The BBS02 is faster and more powerful. The speed limiter on the BBS02 can be removed (up to 99km/hr) with the C965 display. The TSDZ2 speed limit can be set up to 45km/hr (although you can set the wheel size to smaller than actual to bypass this, although the speedometer will not be accurate). 
Also, I have found it difficult to get past 40-km/h on flats with the TSDZ2. I think that is because the assist cuts out beyond a certain level of RPM. A larger front chain ring would help if speed is what you need. The default chain ring is 42T. There is also a setting for “power adjustment”, which may help if I increase it.

With the BBS02, pedaling is just for looks. You don’t put much pressure on the pedals. However, the power is great. The BBS02 has great torque and you can fly off the starting line. With the TSDZ2, you will put in slightly more effort. But let’s be clear, it’s still a powerful electric motor and with not much effort, you can get quickly up to top speed.

Throttle: A hand-throttle is available for both, but it’s unnecessary with the TSDZ2. I didn’t use my throttle either with the BBS02. I preferred to engage the pedals. I found it uncomfortable using the throttle exclusively, since you are putting 100% of your weight on your seat. That is why ebikes need softer seats, full-suspension, or seat shocks. I did use the BBS02 throttle sometimes when I didn’t have my feet in the right position and I needed to accelerate quickly.

Display: The Tongsheng VLCD5 display is big. Slightly too big. I wish it were smaller. Although it does have a USB port [editor: to power a GPS or smart phone]. I ordered the smaller XH18 display which fits on the left handle. Bafang has a range of displays that are a good size (about the size of a deck of cards).

The stock TSDZ2 display

Build Quality: The Tongsheng seems like a nicer build quality. Both drives are solid. The Tongsheng is a little lighter than the Bafang (but also less powerful). The chain ring on the BBS02 seems cheap and people often replace them. The chain ring protector on the BBS02 is plastic and the one on the TSDZ2 is metal.

Noise: The Tongsheng is quieter. While the BBS02 is quiet, there is still a humming sound. I can barely hear the TSDZ2.  [editor: noise between the TSDZ2 and BBS02 seems to be hit or miss, due to manufacturing variations]

Battery usage: I didn’t really test it scientifically, but the TSDZ2 seems to last much longer. Which makes sense, since it has a lower wattage, and it doesn’t deliver quite as much power [editor: adding your legs by pedaling always doubles the miles of the battery on any mid drive. If you swap-in a hand-throttle and only use that, you will get half the miles on the TSDZ2]

Installation: Basically, the same. However, if you don’t have to install ebrakes or a gear sensor, then that saves time. I have not done much bike maintenance before this, so it took me a while, but it was still easy to figure out. I needed to go to the bike shop to have them help me remove the bottom bracket since I didn’t have the right tools for that.

Community: The Bafang products are more popular and have been widely used, tested, and customized. There are more tutorials, information, and guides by far than for the Tongsheng products. 

Bottom line:
I recommend the TSDZ2 if you want an electric motor to assist you, but still retain the intuitive feel of riding the bike. It’s much better for a novice rider or someone who isn’t comfortable dealing with the complexity of controlling the motor. I recommend the BBS02 if you value high speed and power and don’t mind giving up the bike-like feel. Or upgrade to the BBSHD for even more power…”

Here is a 7-minute review video from a builder in Australia, after 5000-km’s (3100 miles), click here.

Temp sensor, and the 8-pin cable

I highly recommend using 48V (or 52V) instead of 36V. If you use the open-source firmware, you can actually unlock the controller to provide up to 30A, but plenty of  experimenters have fried their TSDZ2 by using 18A too often. To get the max possible power, I recommend the old formula of raising the volts as high as it can go, and to use just barely enough amps to accomplish your goals.

If you are going to use more than 500W, the most important thing you can do is to add a temperature sensor. Of course you can use a stand-alone unit with a digital display, but another option is to make sure you buy the TSDZ2 8-pin cable version (instead of the six pin), and that allows you (or the dealer you bought it from) to program the controller to automatically roll-back the amps when the motor starts getting hot.

If you have the 8-pin cable version, you don’t have to use the OS firmware or temp sensor, but…it is there if you ever decide to use it. Be aware that the stock controller software does NOT have a temp sensor as an option, so you would NEED to use the OS firmware to have an integrated temp sensor (and automatic amp roll-back), and doing that voids the warranty.

A fried TSDZ2, and trust me when I say that a fried motor smells bad…

If the TSDZ2 turns out to be “not enough power” for you, then using a temp sensor means that you can at least sell it while it is still running, to recoup some of your investment. The worst case scenario is that you fry it while testing it [without a temp sensor], and then you can’t sell it for any price. 140F (60C) is near ideal when under load. Getting close to 200F (93C) means that you may have de-magnetized the permanent magnets, or caused some other damage.

The black goop [on the left] is high-temp RTV adhesive to hold the sensor against the side of the stator. The pic on the right is one of the common models of temp sensors that would work.

Open Source Firmware

The “hardware” in the controller is easy to understand, they are the the physical components that are soldered together to make up the electronics. The “firmware” is the part of the software that is NOT adjustable by the customer. The purpose of even having firmware is understandable. This drive was designed for the huge European market, and many of those governments are very involved in restricting the power of any ebike product that will be used to ride on their public streets.

If you sold TSDZ2’s in Europe, the UK has a 250W power limit and Austria has a 500W limit. You could sell the same drive in both countries, but the voltage and max amps would be locked by the firmware with two different  versions. Typical “software” adjustments by the customer would be the diameter of the tire, resetting the odometer to zero at the beginning of a trip, the level of assist, etc…

In the USA (where the street-legal power limit is 750W), many powerful kits [like my 1500W BBSHD] are sold as “off road use only”. However there are many Euro countries that don’t allow that. Depending on which country you sell the TSDZ2 in, you can lock the firmware into limiting the volts to 24V, 36V, or 48V…and the amps can be locked at any level that the dealer desires.

One of the biggest problems with mid drives is that the customers who buy them can make stupid mistakes. Even after you have warned them, they will sometimes start their ebike from a dead stop, in the top gear, on a steep uphill, while using the max possible amps. If you do this enough, the drive will overheat and die. The factory drives from Bosch, Yamaha, Brose, and Continental all have integrated safety features to protect you from yourself. The TSDZ2 gives you the freedom to destroy it with bad decisions.

The TSDZ2 controller is made by Kunteng/KT, and it uses a well-known programmable chip, and being able to “re-flash” the firmware is something that was already a known capability. But…once you make the decision to unlock the firmware, what program do you load into it?

A brilliant programmer from Portugal who calls himself “casainho” has developed an open-source firmware program for the TSDZ2. One of the benefits of unlocking the controller is to be able to use a 14S battery (sometimes called 52V). Doing that means you can get 750W from only 15A, in  order to keep the heat as low as possible. Another benefit of 52V is that it gives you the option of using a “56V” EGO lawn tool battery pack (which is actually 14S, regardless of the name).

A battery pack that has 14 lithium cells in series (14S) is often referred to as a 52V pack, but when it is fully-charged to 4.2V per cell (we recommend 4.1V, click here), the actual pack voltage would be 58.8V. The EGO company calls their 14S pack a “56V”. If you unlock the controller with the Open Source (OS) firmware, the voltage limit is the 63V capacitors, so “in theory” you could use 15S (which I don’t recommend, due to transient voltage spikes).

The controllers’ unlocked amp-limit can be set to 30A, which is just silly…since hot rodders have done the hard work for you to verify that 18A is a hard ceiling. Using 20A will just start melting things, and any more amps than that will just melt them faster. If you want to start beefing-up the weak parts inside the motor and controller, you might as well just buy a BBS02.

Video of the TSDZ2 OS firmware, part-1

Here is the video on part-2

Here is the video on part-3

And finally, the video on part-4

Here is a 13-minute video review of the Open Source firmware

If you want to download the new OS firmware, click here

Here is an OS firmware testimonial that I simply had to include…

“…Jeff is actually classified as a quadriplegic. The location of his spinal cord injury from an accident left him with 50% biceps and 35% triceps, and no use of his hands. He is a real trooper. With the TSDZ2 motor, he cycles over 100 miles a week. Sometimes 50 miles on a single ride. There are a lot of people like Jeff whose quality of life can be dramatically improved with a TSDZ2 on a hand-cycle, but it requires the open firmware project to make it work the way they need it…”

Internally Geared Hubs/IGH’s

Instead of using the common external gears on a 7-speed freewheel with a derailleur, or an 8-to-11 speed cassette, some builders like the sleek and uncluttered option of using an Internally Geared Hub / IGH (click here).

Some of the high-powered drives we have seen would break most IGH’s, but when you are using a low-powered and efficient kit like the TSDZ2, you have the option of using any IGH that is available, such as the popular 8-speed and 11-speed Alfine, from Shimano.

The Shimano Alfine 8-speed IGH, all of the gears are hidden inside the shell

Speaking of efficiency, I do  not recommend adding a hand-throttle to this kit. There is nothing wrong with a hand-throttle, but if you like that, the BBS02 has a huge global community that can help you with any issue.

One of the benefits of the TSDZ2 is that it is designed to use a PAS mode, where only pedaling applies added power from the motor. This is the single greatest method to ensure you get a fantastic amount of miles from your battery pack, and that means you can use a very small, light, and affordable pack. Most users are reporting more than two miles per amp-hour, so the 7.5-Ah 56V EGO pack (available at Home Depot hardware stores), would provide over 15 miles.

One TSDZ2 Quirk

“…There’s one problem that happens virtually every time it’s used by a new rider. The unit calibrates the torque sensing every time its switched on, and 95% of riders put one foot on a pedal and then turn the unit on, don’t ask me why, it’s just that the majority of riders seem to. By consequence, the calibration of the torque assist is way out of kilter and you get almost no assist…”

Keep your feet off the pedals when you turn it on.

My Conclusion

I don’t own a TSDZ2, so take everything I say with a  fair amount of skepticism. Here are the benefits and drawbacks as I see them…

PRO’S

1. It’s an affordable 750W “legal” kit, that you can add to your frame of choice
2. It’s the most available torque-sensing kit, and some riders LOVE a sweet TS
3. It is the absolute smallest 750W mid-drive kit available
4. IF…you are willing to void the warranty, there is a free firmware program that allows you to adjust every aspect of its performance and “feel”, and…many users are reporting that it works great (I don’t know, so don’t blame me).

Here are the CON’S

1. 750W is its max, and many new ebikers actually want MORE power
2. Very few dealers in the USA carry it
3. The “Q-factor” (from Quadracepts, meaning the width of the pedal placement) on the TSDZ2 is wider than average. Some riders swap-in the BBS02 crank arms, which reduces the Q from 210mm to 182mm. Some builders swap-in only the right-side crank arm to make the pedals more evenly spaced from the centerline of the bike.

I’ve ridden torque-sensing ebikes at Interbike, and I have to confess, I do like the feel. However, the ebike I ride the most right now is a 1500W BBSHD from Luna Cycle. When spring of 2019 arrives, my next project is boosting the BBSHD power to 2500W, so a 750W drive doesn’t interest me, no matter how smooth and seamless the power application is.

USA dealers

One current USA retailer for the TSDZ2 is David in Tennessee at “eco-ebike.com”, which can be found by clicking here

Another USA dealer is Mark in SLC Utah, Electrify Bike Co, which can be found by clicking here.

Written by Ron/spinningmagnets, December 2018

There are several things I really like about this build, and if I was building a daily commuter, a longtail electric cargobike with a large battery pack and a direct drive hubmotor would be at the top of my list.

The header pic is from the youtube channel “skyBridgeConcept”

The Nissan Leaf battery pack

The really unusual thing about this build that immediately jumps out at the reader first is the large battery pack, made from 2016 Nissan Leaf cells. The Nissan Leaf is a car, and although the pack uses flat foil cells, Nissan chose to assemble the cells in metal canisters that are called modules. There are four cells inside each module, and the stock configuration is two cells in series, and two cells in parallel (2S / 2P). For more details, click here.

Here is a pic of two stock Leaf modules. If you don’t change the internal configuration, the threaded connectors on a single module provide 82-Ah, and a nominal 7.4V

One of the things that the builders who use Leaf cells seem to like about them, is the handy stock threaded contacts for the positive and negative posts (along with the aluminum cases) They also have a smaller central threaded post for the balancing connection to the Battery Management System  (BMS). These contacts make it very easy to build up a pack for a motorcycle, or a home power supply to be used during a power outage.

Due to their large size, it is rare for these cells to be used for an electric bicycle, but I have seen several motorcycle builds that have used them. The side dimensions are 290mm X 216mm (11.4-inches X 8.5).

Two Leaf modules shown above, containing four cells each, for a total of eight Leaf cells. Shown here with some of the metal module case removed.

Twenty cells in a stack, with a module side-plate on the top and bottom. The stock connectors have been removed, and the pack is now a 1P configuration. The bare cells are 7.2mm thick.

In the pic above, all of the stock 2S / 2P threaded connectors have been removed, and this pack is now a 1P configuration. These second-generation cells (2015 and newer) are 41 Amp-hours each, so the stock module would be 2P / 82-Ah (the first-gen cells are 33-Ah). The cube of cells shown above is 72V (36V + 36V) and 41-Ah for 3000-Watt Hours (WH) of total power (which could also be called 3-kWH). Its not unusual for a reasonably efficient system to deliver two miles per amp-hour, so 41-Ah would likely provide over 80 miles of range.

The Leaf cells are made by AESC. The early cells have a 3C current rate for an output of (33-Ah X 3C =) 99-amps. The early Nissan Leafs experienced longevity trouble in hot climates, possibly because they are air-fan cooled, rather than the more expensive liquid-cooling used by the Chevy Volt and Tesla. Cold climates did not have the same problems. For instance, Arizona can be 115F in the summer (46C), even before you apply a load to the Nissan Leaf.

One of the things that Nissan improved in 2015, was the C-rate of their new second-gen cells (C-rate is their ability to provide Current). Since the cars performance was not significantly improved, the higher C-rate simply allowed the battery pack to run cooler under load. The second-gen 41-Ah cells have a 10C rate, so they can provide (41-Ah X 10C =) 410 amps. It’s no wonder these cells are popular for motorcycle conversions!

Configuring twenty Leaf cells into two sub-packs of ten cells each, packaged into one bundle. The copper material for the connectors were taken from common water pipe, sourced from a hardware store.

One of the interesting things that this builder did was to configure the twenty cells into two sub-packs with ten cells each. Ten lithium cells in series are commonly called a 36V pack, and two of those in series would be called 72V.

He did this so that he could use two common 36V chargers, and also use a more common pair of 36V BMS’s, since 20S / 72V BMS’s and chargers are rare. The discharge cables that power the controller and motor are not routed through the BMS, so the cells must be capable of providing more amps than the controller will be drawing.

If not, any high-amp demand from the controller might damage a low-amp battery pack (without the BMS in-line to protect it). Fortunately, these cells are known to easily provide very high amps, and the controller is only rated for 60A. These BMS’s will only be used for protecting the charging and balancing of the cells.

The custom aluminum case for the 72V pack.

Hubmotors and Moped Rims

Mid drive systems and geared hubmotors have their benefits, but…if you have enough power, like (72V X 60A =) 4300W…a direct drive hubmotor is a robust and simple system that can climb some fairly significant hills without overheating.

But which direct drive hubmotor to use? Joel chose the MXUS 3000W, in the V3 4T version. This motor can easily handle the 4300W that Joel is using. When accelerating, your system might occasionally draw the peak watts, but once you achieve your top speed and then enter a cruise phase…the watts will slide down to a much lower level.

The MXUS 3000W V3 4T, opened up.

Lacing the MXUS to a 17-inch moped rim, which is much stronger than a bicycle rim.

The RPM’s of a motor are the “Voltage times the Kv” of the motor. The MXUS is available in several Kv’s, and the Kv of this 4T model is 8.9 RPM’s per volt, which equals 640-RPMs (when using 72V). Of course, the actual top-speed must also take into consideration the diameter of the tire, plus the air-resistance, and also the weight of the rider, bike, and cargo.

Joel chose a 17-inch motorcycle rim, and a tire with a 21-inch true outside diameter. Bicycle wheels and moped/motorcycle wheels are measured differently, and this 17-inch moto rim is halfway between a 24-inch and 20-inch bicycle wheel. If using a one-cross pattern on the spokes, you can even order a slightly smaller 16-inch rim, which is very close to the size of a 20-inch bicycle wheel. If you are interested in using a moped rim and tire set, you can read our article on them by clicking here.

A one-cross pattern of 12-ga spokes

I believe this was a good decision, since the choice of swapping-in a smaller diameter wheel (compared to the stock 26-inch), helps the potential heat of the motor under load.

Controllers apply amps in an attempt to get the motor up to it’s design RPM’s. The longer it struggles to reach the RPM’s that the throttle is requesting, the hotter the motor will get. The worst-case scenario would be a small-diameter motor with a high Kv, installed into a large diameter rim.

If you move up to a larger diameter motor, you would be placing the magnets farther away from the axle, which will give them more leverage, which improves the torque without increasing the input watts. Then, if you swap to a smaller rim, you will again increase the wheel torque compared to the larger rim, also without raising the input watts. Of course a smaller rim would lower the road speed of the wheel, so you would need to then upgrade to a faster Kv model of your motor, in order to keep the same top-speed. The 4T that Joel chose is an average winding, and it can be found with a faster 3T and also a slower 5T.

Another benefit of using motorcycle rims is that their tires are very resistant to getting a flat from nails or thorns in the road, which is a huge benefit if you are relying on your ebike to get to work every day. The tire Joel chose is from “Gazelle”.

Powerful hubmotors need two strong torque-arms. Joel ordered these to be water-jetted and mailed to his home.

When a powerful hubmotor tries to spin forwards, there is an equal force trying to spin the axle backwards, so…it will need two very strong torque-arms to hold the axle stable. The torque-arm shown above is a great example.

Altering the Yuba frame

Joel knew he would need to alter the Yuba Mundo frame to fit the Leaf cells, but he was certain he wanted to have both of them, no matter how difficult it might turn out to be.

The Yuba Mundo longtail cargobike

The red square shown above is where Joel wanted to mount the Leaf battery pack, but he also knew there was no way he could pull that off without cutting into the frame. Joel made certain that he bought a version that used a mild steel frame (hi-ten), so he could easily weld onto it (the other options were a cargobike with Chromoly-steel, or possibly aluminum).

Measure twice, and cut once.

The first cut is always the most painful. You have to get it right, because if you cut away too much, you might need additional repairs that are time-consuming and ugly. Once a small portion of the frame was cut away, Joel could insert the battery pack case, and then begin the process of evaluating what strengthening additions would be possible.

As you can see in the pic above, Joel made the repair extra strong, so he could ride this cargobike at high speed, with no fear of the frame breaking.

Here is the second round of additional strengthening tubes that were welded-in.

Additional Electronics

Below is a pic of the Sabvoton 60A controller Joel is using. He mounted it under the cargo rack, and added a fender to keep road-dirt off of it.

The Large Sabvoton controller

Here is the control panel that Joel added to hold the charging socket, and the on/off switches.

To charge the two 36V sub-packs, he is using two RC chargers

A high-amp fuse, and four Cell-Logs to monitor each cell in the pack.

Almost done!

Diverting the Chainline

Once Joel re-attached the drive-chain, he realized that if he moved the battery box far enough over to avoid hitting the chainline, the weight of the battery would be too far to the left. The battery pack as shown is 174mm wide, roughly 6.9-inches. (for those who are interested in something similar, a 14S / 52V pack of Leaf cells would be 43mm thinner for a total of 101mm, roughly four inches wide).

Joel decided to keep the weight of the battery pack in the centerline of the frame, and to accomplish that, he then decided to route the chain to pass under the battery box.

The long drive-chain rubbing against the battery box. The large chainring he chose has 53 teeth.

The chain idlers that re-route the chain under the battery box

The top run of a bike chain is the part that experiences tension when you are pedaling, and any chain tensioner is typically mounted on the bottom run of chain. However, Joel decided that this was the best compromise for his needs. He also chose cranks from a fatbike to provide additional clearance for the pedals.

Where to get?

The Hybrid Auto Center in Las Vegas has a new website for purchasing used cells from wrecked electric vehicles, called the EV Battery Center (click here). If you are interested in flat foil cells, but you want something smaller than the Leaf cells, I have been reading about many builders using cells from the Chevy Volt, which has a side dimension of 177mm X 127mm (7-inches by 5 inches) and they are 6.3mm  thick (1/4-inch).

Leaf cells are 11.4-inches X 8.5…

There are many other brands of hybrid and electric car on the road, so keep an open mind when shopping. However, due to the high number of Nissan Leafs and Chevy Volts produced, these two cells are the most common to find.

The Chevy Volt cells are from LG Chem in South Korea, and they are about half the size, compared to the Nissan Leaf

The Chevy Volt cells have roughly 45-Ah of range, and are rated for 7C, so 45-Ah X 7C = 315A…still VERY powerful!

If you want another option for cells that are a small size for a hot rod ebike, I have found a 200A cell that is only 190mm X 140mm (7.5-inches by 5.5). They are made for a Chinese company that manufactures hybrid city buses. The Volt cells are the same size, but have many more Amp-hours, however…due to their popularity, the Volt cells can be hard to find.

High-amp cells that are small, from Battery Hookup

Since these are constructed for max amps instead of range, they only have 8-Ah each. The company “Battery hookup” sells four of these for $28 plus tax and shipping (click here).

And for your entertainment, I have a video of youtuber “AveRage Joe” assembling a pack of these, at the 26:40 mark (click here).

Written by Ron/spinningmagnets, December 2018

The Bafang Ultra Max mid-drive has the biggest motor you can buy in a factory turn-key ebike right now. It is labeled as a 1,000W drive, but…it is capable of MUCH more. Not only that, it has ISIS cranks and torque-sensing, so…let’s get started.

The MOTOR

Bafangs internal labeling system calls this the MM G510.1000, and it’s design makes several improvements over my favorite drive, the BBSHD. The BBSHD is a kit that slides into just about any frame you like, but the Ultra Max requires a proprietary shell to mount it (see below).

The first thing that pops out at the casual observer is that the Ultra has a larger diameter motor. This increases the amount of leverage that the magnets exert onto spinning the rotor, without any additional watts applied to it, compared to the same watts being applied to a smaller diameter motor with the same copper mass. The other thing that this helps is the efficiency, since the “tangential magnet speed” is faster for a given RPM.

The BBS02 on the left (known to run well at 1000W), with the Ultra on the right. The diameter of the BBSHD would be about halfway between the two. The BBSHD is often run at 1500W, so the Bafang Ultra should easily be able to handle 2000W or more. The stator has 12 concentrated coils, and the rotor has 8 magnets (4 pole-pairs). Pic courtesy of endless-sphere member Ivanovich_k

What that means is…the controller will apply higher amps to the electromagnets in the stator until the permanent magnets in the rotor are spinning fast enough to reach the motors’ top-speed (the so called “Kv” of the winding). The faster the magnets pass by each other, the shorter the pulses of watts are that are applied to the electromagnets. Using lots of small pulses ‘can’ provide the same total power that is applied, compared to using fewer long pulses, but…using long “on” pulses will heat up the MOSFET’s in the controller, and also the electromagnets in the stator.

Be aware the Ultra Max stator is narrower than the BBSHD, but the diameter is larger enough that it still does have more copper mass.

Another thing that is worth noting is that the BBS02 in the picture above uses what’s called “Surface Permanent Magnets” / SPM on the rotor, and the Ultra (along with the BBSHD) uses a style that inserts the magnets a small distance away from the surface of the rotor. This style is being seen more often these days, and it’s called an “Interior Permanent Magnet” motor / IPM.

This design allows the magnets to run cooler, which is important because one of the limitations on how many amps a motor can use is the heat that is generated by “eddy currents”. The stator core is made from a stack of very thin steel plates in order to reduce eddy currents, which are generated anytime a ferrous metal is rapidly passed through a magnetic field.

Using a stator-core that is made from thin laminated plates (coated with a lacquer to electrically isolate one plate from the other) is a cost-effective way to accomplish a limitation of any eddy current heat, but…unlike the laminated stator-core, the magnets are solid chunks of metal. With the older SPM motor designs, the magnet body itself becomes a source of waste heat.

With an IPM, the permanent magnets will “magnetize” the slim section of steel between them and the electromagnets in the stator. This keeps the magnetic field strength in the air-gap at an acceptable level, while still placing the actual permanent magnets a short distance away from the air-gap. Permanent magnets can lose their magnetic power if they get too hot, so…by doing this, you can use more “temporary peak” amps without overheating the magnets.

ISIS cranks, not square taper

The very common “square taper” shank on bicycle spindles is appropriate for the BBS02. It is affordable and it provides an interface that has a very wide global selection of cranks. For instance, if you are looking for an obscure offset in a pair of crank-arms, the square taper spindles (frequently found on street bicycles) will have the best selection…including cranks made of titanium, carbon fiber, aluminum, and steel.

Square taper spindle on the left, and a 10-spline ISIS spindle on the right.

The BBSHD also uses a square tapered spindle, which I believe was simply chosen to save on costs. When comparing the BBS02 to the BBSHD, it was obvious to me (years ago) that the larger BBSHD would be the drive of choice for off-roaders (off-road is where there are no power limits in many countries).

The one place where you can consistently find the stronger (and more expensive) 10-spline “ISIS” format for the spindles is on serious off-road bicycles. This is the major clue to Bafangs philosophy about the design choices they made.

For instance, when it comes to a “street legal” electric bike, the USA has a 750W power limit. Then…Canada, Switzerland, and Austria have a 500W power level, and many other countries have a ridiculously low 250W power level. The Bafang label claims a 1000W power level, but they are actually being run at over 2000W, and THAT…is not street legal anywhere!

[edit: angry emails have informed me that Oregon and Virginia have a street-legal power limit of 1,000W]

Torque-Sensing

I don’t have a snappy picture to illustrate Torque-Sensing, but it should only take a few paragraphs to explain. Most “Pedal Assist Sensor-PAS” designs allow the bike to add power by simply sensing when you are pedaling (no hand throttle). In fact, some countries in Europe only allow PAS.

The affordable PAS solution is to have a “speed sensor”, where pedaling causes a disc with several embedded magnets to pass by some type of fixed magnetic sensor. However, it can take a 1/4 turn of the pedals to engage, and a half-second of stopped pedals to dis-engage. Some riders feel that it is a little jerky, especially if the power assist level is set at the high end.

A torque-sensor is more expensive, but all of the modern versions that are readily available provide an “instant-on / instant-off” experience when you start and stop pedaling. Most of them even sense the amount of pedal pressure that the rider is applying, and then it adds motor power accordingly. Who likes this? Off-roaders.

Well, actually…everyone likes it, but…off-roaders are consistently willing to pay more for it. It makes sense. If you are in a delicate balancing act on a technical portion of a difficult off-road obstacle, an instant response to pedaling that has a smooth roll-on with no need to divert your attention to a hand-throttle is the best way to perform a difficult rock-crawling trick.

Controller

The pic below shows that the factory controller for the Ultra uses 12 MOSFET’s. A Field Effect Transistor / FET is an “on-off” switch that controls the amps that are fed to the three phases of the motor.

The controller for the Ultra Max. Notice the “63V” max capacitor. This drive can flow the 58V max from a 14S / 52V battery pack, or the more common 13S / 48V pack.

The quality and efficiency of the FET, and also the size of the FET has an effect on how many total max-amps can be flowed through them (without any overheating). Even so, 12 FETs is a LOT! If you are only running 52V X 20A = 1000W (like the label), it will barely get warm…

Gear Reduction

The motor Kv is 55-RPM’s per volt, and the triple-reduction between the motor and cranks is 18:1

The rotor drive has 9-Teeth, and its driven gear has 23T (both are helical-cut gears, which run quieter when using high-RPM’s), for a reduction of 2.5:1. The second helical gearset is  66T/25T  for 2.6:1 . The third gearset is 46T/17T for 2.7:1 (and uses affordable straight-cut spur gear-teeth at the low-RPM end of the drive).

Having more stages of reduction will cost more, add complexity, add mass, and add friction. However, it can also allow the drive system to provide higher wheel-torque with the same size of motor. Pic courtesy of robocam.

This builder has removed the stock controller and is trying to fit a controller model called a “Phaserunner”. If you don’t have a grease preference when re-assembling, Mobil-28 synthetic is my go-to option. Pic courtesy of ES member Daxxie.

The Proprietary Interface

The benefit of a conventional mid-drive kit is that it can slide into the “bottom bracket” of almost any bicycle frame that you like. The drawback is that it limits the arrangement and size of various components inside the drive. Proprietary drives have much more design freedom.

The most popular factory mid-drives are the Bosch, Yamaha, Panasonic, Continental, and others.

This builder found a titanium frame that uses the Bafang Ultra Max mounting shell. Welding aluminum to titanium requires experience and a TIG-welder. Pic courtesy of Daxxie.

Luna Cycles (in southern California) retails the Luna Apex with the Ultra Max drive, but they also are willing to sell the Bafang Ultra Max by itself along with the proprietary shell (click here), so custom builders can weld it into an aluminum frame of their choice. Do your homework before purchasing the shell. I believe it is aluminum, which may restrict the frames that can accept it…

The Bafang Ultra Max, when purchased as a separate unit from Luna Cycles

What ebikes have it?

The Bafang Ultra Max was first shown at the Taipei bicycle show in 2017, and it was marketed as being more powerful and less expensive than the popular Bosch mid drive.

The 27.5-inch tire version of the Frey full suspension frame.

Frey was an early adopter of the Bafang Ultra Max drive, as seen in the pic above. They also have a hardtail version, and a fat tire version too. The Ultra is reported to allow the use of 1600W of power in the factory-authorised high-powered versions. It is reported to provide 160-Nm of torque, and it also provides that power up to 28-MPH (45 km/h), which coincidentally is the street-legal power application limit in the USA.

(The most powerful Bosch mid-drive is listed as providing 90-Nm of torque, and the recent “TQ” mid drive is listed as 120-Nm)

Exess, from Germany

I don’t know anything about Exess, but they seem to be very upscale.

Volton A-Trail

Luna Apex

Most of our readers are based in the USA, and if one of them wants to look at possibly buying an ebike with the Bafang Ultra Max mid-drive, Luna Cycles in southern California should be your first stop. It appears on the upscale Apex, and also on the more affordable Apollo. Be aware, when Luna has them in stock, they often get snapped up very quickly.

One of my favorite writers is Karl from ElectricBike-Blog.com. Here is a link to his impression of the Luna 2500W Ludicrous Apex.

Over time, I believe more retailers will begin carrying a model of ebike with the Bafang Ultra Max mid-drive, and as I find them, I will add some to this list. Below is a teardown video showing the insides of the Bafang Ultra Max…

Written by Ron/spinningmagnets, January 2019

When it comes to installing an electric bike kit, many potential buyers are nervous about the technical difficulties of that task, and they are drawn to systems that have a very simple installation, even when that choice might limit the performance aspects of the kit. Here is an index of several low-performance kits that make the installation super easy.

[Before we get started, I want you to know that I appreciate any company that is trying to sell electric bike stuff, so I do feel bad about my negative reviews below, but…I have to be truthful to my readers, and these kits keep popping up in the news. For some reason the media seems to be enchanted by every new version…]

#1, Copenhagen Wheel

I am putting this kit first, because they seem to be the most well-known, and that is because they have had the most comprehensive advertising campaign. Since they use a torque-sensing “Pedal Assist Sensor (PAS)” that is built into the rear hubmotor, there is no need for a bottom-bracket (BB) PAS, or a hand throttle on the handlebars.

One of the main features of the “All In One” hubs is that…the battery pack is built into the wasted space that exists in the center of the hubmotor. I have to confess that I like any company that is trying to build, sell, and promote electric bikes. That being said, my biggest concern about all-in-one hubmotors is the size limit on the battery pack. This forces the buyer to accept low performance and short range, in exchange for saving a couple hours on the installation.

If Copenhagen Wheel contacted me for technical advice, I would have suggested that they have an optional kit where there was no battery built-into the hub, and there was a socket for any 48V/52V battery to be plugged into it. But then again, if they did that and went out of business, maybe it would be my fault, or maybe they would have gone out of business anyways…

The Copenhagen Wheel contains everything, the motor, controller, battery, and PAS-throttle

Before we get any further, I want to confess that I don’t recommend any of these all-in-ones. I live in the USA, and my most often ridden ebike has a 1500W Bafang BBSHD. The one change I plan on for this next summer is to swap-in a higher-amp controller for 2500W (and also to build a DD-hub cargobike).

Almost all of these “all in ones” are marketed in Europe, because of their ridiculously low 250W power limit for “street legal” electric bikes. If you live where the terrain is flat (and you want to obey the law), then these 250W all-in-ones are actually not horrible. The problem I have is that there are hills where I live, so…

The Copenhagen Wheel is reported to have been developed at MIT, the Massachusetts Institute of Technology. That is a world-famous high-level university. If this is true, then I am disappointed in MIT (I didn’t go to university, and I know high-school students who could have done better). The one thing they got right was to name it after Copenhagen.  That is a city that is very pro-ebike, AND…it is very flat (no hills). This kit has low power and short range, but if you live close to work (and you want an easy and quick installation) it actually is perfect.

The large red disc stands out, but I like that. This is clearly for someone who is NOT trying to hide that it is electric. If you can’t hide it, embrace it! The custom spokes probably didn’t help. If you break one, they would be easy to re-install, but you could only get them from the company you bought the kit from.

It WOULD also be perfect for the very flat city of Manhattan (in New York, USA), but…NY is cracking down on ebikes. It appears that their environmentally-friendly politics only work outside of the paradigm of taxis, limos, and the subway gathering millions of dollars each month into the city treasury (during the Watergate scandal, the investigators mantra was “follow the money”).

#2, Zehus / Flykly

The Zehus “all in one” holds a soft spot in my heart, because they were an early adopter of this style. I respect entrepreneurs who take risks and are new to the game. Also, Zehus purchased control of “FlyKly” to gain access to their patents.

In June of 2014, we reported on the Zehus drive as a part of the the beautiful and expensive Pininfarina-designed Fuoriserie ebike.

The Zehus hubmotor

The graphic shows that they have a 2P battery pack (two cells in Parallel) using 18650 cells. If they are using modern 10-amp 3400-mAh cells, they have roughly 6.8-Ah of range, and the graphic shows an 8S voltage of a nominal 28V, and 20A of peak amps available.

The Zehus hubmotor

#3, iMortor 1.0,  from Yunzhilun 

This kit was originally called “UrbaNext”, when it began on kickstarter and Indiegogo. If you don’t do anything else today, please watch this short video from a German blogger reporting on this ebike kit. Don’t ask why they spell it “iMortor”.

This kit has a battery pack that is 10S/1P (ten of the 18650-format cells), so…using currently available parts, it is 36V /3.2-Ah…(see the 10:33 mark). The MH1 cell shown from LG-Chem (in the 18650 format) is rated for 3200-mAh and 10A, so…

That being said, this product is advertising itself as having a Field-Oriented-Control (FOC, the best kind of sine-wave controller), and they are available on Amazon. Plus, they have a wireless smart-phone app that connects your device to the controller. The single cable is only to connect to the dashboard.

As much as I feel the iMortor is under-powered, it does have some interesting features. The battery pack is the half-moon shape on the bottom left.

The half-moon protrusion on the right side is the removable battery pack. The kit is also reported to have a socket that allows the user to plug in a bottle battery pack to extend range.

The iMortor 1.0 provides 250W up to 27-km/h, (16-MPH, the legal limit in the EU), using a 10S / 1P battery pack.

The iMortor 1.0

#4, iMortor 2.0

The newer and larger iMortor 2.0 provides 350W up to 34-km/h, (20-MPH, the legal limit in the USA). Although the 2.0 version uses a lower voltage of 24V, it also has more cells inside that are configured in a 2P arrangement, so it can draw more amps. It is 7S / 2P (14 of the 18650-format cells).

The Yunzhilun iMortor 2.0

The odd protrusion on the left pic is the proprietary battery back that is removable. Yunzhilun also sells larger 24V bottle-shaped batteries that can be plugged-into their hub to extend the range.

#5, Electron Wheel, by Currie

The Electron website can be found by clicking here. If I ever find pics of the insides, I will post them here. Currie is a HUGE global ebike company. They may not be well-known in the USA, and that’s understandable because they are focused on the large EU market for 250W ebikes. I’ve taken dumps that used up more than 250W after a chili cook-off competition…

The Electron Wheel, by Currie

__________________________

#6, Evelo Omni Wheel

If you live in a city with flat terrain, the Omni Wheel actually isn’t too bad. It only uses a 7S / 24V battery pack, but, the geared planetary reduction means that the modest 250-Watt’s of input are converted into a lot more wheel-torque that you might expect from 250W. This short video shows that it even has FOUR cells in parallel (4P). If they are using a modern 3.4-Ah cell, then 3.4-Ah X 4P = 13.6-Ah of range, along with a decent amount of amps.

The Evelo Omni Wheel

A closeup of the Evelo Omni Wheel geared hubmotor. The aluminum fins cool the controller.

The motor on the Omni Wheel is a small 250W unit (see below for perspective, the motor is the white disc in the center), but…the fact that it is “geared” means the available input watts are magnified mechanically into the maximum possible amount of wheel torque.

Evelo Omni Wheel. Using a tiny geared 250W motor, integrated controller, and seven series groups of 4P cells using the 18650-format.

#7, MIT Greenwheel

If you search for all-in-one hubmotors, the MIT Greenwheel will show up as being hot in 2008, so…here it is…this design group decided that within the available diameter of hub, they wanted the battery to be bigger (occupying the outer diameter area) and the motor to be smaller (in the center).

The battery pack is 8S / 2P, so it uses 28V and depending on the 26650-format A123 cells it used in 2008…it’s hard to say how many Amp-hours (Ah) it had, and amps of current it could put out.

The MIT Greenwheel

#8, Rool’in

The Rool’in company website is based in the UK. This model is available in 28, 26, and 20-inch tire diameter. Here is a video they posted.

The Rool’in Wheel

#9, Daymak Shadow

This ebike was a hot new item in 2011, and then…they quickly went out of business. The articles talked about how the throttle controls were wireless, but the power was only 250W, and they are no longer available for sale…

The Daymak. Was it 2WD? Who knows…

Motor: 350W continuous (Peaks at 500W)
Battery: 36V 10-Ah Lithium
Controller: Daymak Drive
Weight: 59 lbs / 26 kilos
Top Speed: controller-limited to 34 km/h (20-MPH)
Uses “Frequency-Hopping Spread Spectrum” technology to prevent interference
ISM Wireless Frequency (2.4 GHz)

#10, EZ Wheelie Wireless Electric Bike Conversion Wheel

“…Completely wirelessly, this all-in-one gadget fits any bike size from 20 to 29 inches. Thanks to its versatile design, EZ Wheelie is compatible with most bicycles, including kid’s bikes and mountain bikes. Additionally, the wheel takes just one minute to install. Simply download the app and start riding. You can also use an optional Bluetooth display to control the bike. Moreover, the wheel comes with multiple battery size options, offering a 20, 40 or 60-mile range. It also provides five levels of pedal assist, allowing you to ride up to 20 mph without doing all the work…

The EZ Wheelie blah blah blah kit

#11, DK City Hot Wheel

Not much info available, but I am impressed that they chose a battery that is 14S / 2P. Here is a video that they posted. The motor is geared.

The DK City Hot Wheel

DK City Hot Wheel

#12, db RevO

These guys aren’t posting much info about the specs, but they seem to care most about having several colors available.

The colorful db RevO

My Opinion…

As I stated before, I am not a fan of these. They concentrate ALL of the motor and battery weight into a single wheel, at one end of the bike. However…if you live in a flat city and don’t need a lot of range or power, they aren’t horrible.

That being said, my biggest peeve is that the battery is built in. I want the option to mount the battery where I want it to be. I also want the option to swap-in a larger battery if I want to ride a much longer distance (forget about any of the range claims in the ads for these). I also want to be easily able to buy and mount a new battery when the old one wears out.

I decided to compile this list so I have something to link to when someone asks me about these…again…and again…

Written by Ron/spinningmagnets, January 2019

This is news because Pedego sells more turn-key ebikes in North America than anyone else. What makes it strange that they waited so long to start carrying a mid drive model in their catalogue. When they started out, they became famous by making beach cruisers with a small hubmotor.

Pedego’s early ebikes

Pedego is a company who’s mere existence is a life-lesson in marketing. Let me start by describing something from my own life. When I was younger, I re-roofed my own house (after having worked on a roofing crew for a short time), and by doing it myself, I saved over $1,000. It was hard work, but at the time, my spare time was well worth $1,000 for one weekend.

What I’m getting at is…Pedego products seem a bit pricey for what they provide, and yet they are the largest turn-key ebike company in the USA. Clearly they have a customer base that is willing to pay more for what Pedego supplies, so…what do you get for the money?

The 48V Pedego beach cruiser is the foundation of Pedego’s bread-and-butter

Look at the pic above of this orange beach cruiser. It has everything that customers strongly respond to on a test drive, and it deletes anything that doesn’t directly affect a test drive.

Notice the space between the seat tube and the front of the rear wheel. This is a slightly “stretched” frame, with a mildly “feet forward” comfortable riding position. It is comfortable to ride, and you aren’t putting body weight onto your wrists while leaning forward, like a racing road bike.

Suspension is expensive and heavy, so this bike makes sure to have the key feature of a “beach cruiser”…fatter tires. They may have only been 2.4-inches  wide, but sometimes that’s enough (at the time).

The Pedego Interceptor in yellow

Disc brakes. The early versions had cable-operated units with small diameter discs, but…if your fork has the disc-mounts, each buyer could easily upgrade the brakes if they wanted. And to be fair, many customers are happy with cable-operated 160mm discs, compared to rim brakes. All of their new brakes use a 1800mm disc or larger…

Pedego ebikes sold OK at 36V, but when they went to 48V and a larger hubmotor, there was a big bump in sales.

Color…many bicycles (and ebikes) are only available in one or two colors. Pedego has many bright colors from the very beginning, and they were an early adopter when it came to color-matching the rims. That may sound trivial, but…the guys who run Pedego are millionaires, and 99.9% of the people reading this are not. When internet posters made fun of them for selling over-priced beach cruisers, they cried…all the way to the bank.

The Founders

Pedego was started and is run by two friends, Don and Terry. I had the pleasure of interviewing Terry at the 2015 Interbike, and his intelligence and enthusiasm are infectious. Don and Terry were not ebike people who decided to start a business. They were successful automotive-parts businessmen who decided to get into ebikes.

Don is on the left, Terry on the right. Look at how small the 36V geared hubmotors were back in the beginning.

These guys started big, and stayed big. They placed large bets, and they only bet on a sure thing. The shift to adding mid drives to their catalog is the best endorsement I can think of for ebikes in the USA. Fast-growing companies like Luna Cycles are edgy and take bold risks. Pedego is the type of company that watches Luna Cycles, and then they “copy what works”.

All of these new models listed below use an aluminum frame to save weight, they continue to use disc brakes, and all of them use a torque-sensor instead of the cheaper “speed sensor” to activate the Pedal-Assist-Sensor / PAS option. That is where you are pedaling add add power, instead of using a hand-throttle.

I was struck by how each of these three models use a different mid-drive system. Most ebike companies negotiate to get the best possible price on the motor-system from the supplier, which often ends with the motor supplier demanding exclusivity. Haibike and Pedego are both large enough that no single motor supplier can make such demands, so both have models that use whatever motor the retail company wants for that model.

All three of these models will provide power up to 20-MPH (32 km/h). You can go faster than that if you want, you just don’t get any electric assist over that speed. One thing I have to say about Pedego…over the years, they have continuously added a variety of models to their lineup. They have cargo bikes, fat-tire models, and even an “extra low” step frame.

Pedego City Commuter

This is the least expensive Pedego mid drive at $3600. The most curious thing about it is that they refuse to tell you where they get their motor system from. My contacts in the industry indicate it is most likely to be a spec unit from Bafang, but nobody will publicly verify that.

It looks like it has a rudimentary suspension seat-post. I really like the Suntour NCX, but anything is better than nothing when you are riding an unsuspended frame.

The 2019 Pedego City Commuter mid drive

The 48V system is reported to provide 95-Nm of torque, which is actually at the higher end of factory mid drives (Bosch, Brose, Panasonic, etc). It uses a square-taper bottom bracket cartridge with a torque sensor. The Shimano 7-speed freewheel is an affordable and adequate gear-set for most street hills.

If the drive is truly limited to the rated 500W, then the 48V battery will be limited by the controller to 11A. Doing that and using a PAS means that you should get a very good amount of range from the more affordable 10-Ah battery pack. However, for getting a longer life out of the battery, I highly recommend the larger optional 15-Ah pack (even if you don’t need the added range).

The Brakes are Avid BB7 cable-operated calipers with 180mm diameter discs. This is the clear leader for affordable brake systems. As the pads wear away, the gap can be adjusted by a simple knob on the caliper, no tools needed.

There are three frame options. There is a diamond frame and also a step-through frame using 28-inch hybrid tires, along with an optional cassette (instead of the 7-speed freewheel). The third frame option provides a size for the shortest riders and uses 26-inch tires.

If you want more details about this model, here is a link to the Pedego PDF

Pedego Conveyor

This $5000 model places the weight of the battery and motor in the center, which is widely regarded as the best possible location for the balance of the bike. This is useful when lifting it onto a cars cargo rack. The lack of a welded cargo rack means you can easily swap-in a Thudbuster or Suntour NCX, both of which are highly regarded for un-suspended frames.

The 2019 Pedego Conveyor

This particular model uses a Gates belt (instead of a chain), and also a Shimano Alfine 8-speed IGH (pronounced al-FEE-nay). That particular combination is unusually quiet, whether you are pedaling or just coasting along.

The Conveyor uses the well-known Brose-S drive. It has a high reduction with an internal belt-and-pulley set. This version of the Brose is programmed for 250W of input, and it’s efficiency is revealed by it’s ability to turn the modest 36V X 7A = 250W into a surprising 90-Nm.

One interesting feature is that the battery uses the Rosenberger RoPD magnetic connector for charging.

That means this model is not a hot rod, but it will provide a significant range from only 13-Ah of battery. There is only one size of aluminum frame, which uses Schwalbe “Super Moto” 27.5 X 2.4-inch tires. Tires this fat work well to smooth-out common road irregularities.

The brakes are Tektro 2-piston hydraulic calipers, using 180mm diameter discs, which is definitely appropriate at this price range.

If you want more information about this model, here is a link to the Pedego PDF.

Pedego Elevate

I am certain this is a rebadged mountain ebike that is made by someone else. That being said, this is not actually bad. One of the things that Pedego has going for it is that they have a deep and wide dealer network, and the highest level customer service (good CS costs more). In fact, that is exactly why many of their customers will buy a Pedego instead of simply adding a kit to an existing frame (in order to save $1,000). I have no doubt that they will sell plenty of these, even though they are priced at $5,500…(not me, of course. I am talking about rich customers here…)

The 2019 Pedego Elevate

This full-suspension aluminum frame comes in two sizes. I scanned the specs to find something that I can recommend as an upgrade, but…it looks like someone did their homework. The Shimano STEPs mid drive motor has a small chainring (which enhances torque and limits motor heat). The gear-set is a Shimano SLX M7000 11-speed cassette, which is an awesome number of gears once you add a motor.

The bottom bracket (BB) is a Shimano Hollowtech-II, and my off-road friends tell me that this is the good $h!t…movin on to the brakes, it uses a Shimano Deore Hydraulic caliper set, with 203mm discs. I haven’t test-ridden anything that is considered “better”, but this is definitely a wonderful choice.

The tires are Maxxis “High-Roller-II”  27.5 X 2.8, and this is firmly in the recent “mid fat” category that is proving to be popular. Forget the numbers and reviews, go for a test ride on mid-fat tires.

Finally, let’s talk about the motor. The Shimano STEPs E8000 is not a hot rod, since it takes a modest 36V and only converts it to only 70-Nm or torque. but…it is well-engineered, and has a reputation for running very quietly, and very reliably.

The Shimano torque-sensing is as good as anything that is available. That means that it has a smooth power-up and power-down when you begin pedaling or when you stop. The power is also available instantly, instead of the slight delay that we find when using a cheaper “speed sensor”.

If you want more details about this model, here is a link to the Pedego PD.

Lets wrap it up

I have to mention this again. Why would someone pay so much for an ebike, when it is cheaper to add a kit to an existing bike? Pedego has a 2-year warranty that their customers trust. Also, I have to mention that Pedego dealers have rentals, which means a potential customer can take a test ride without having to talk to a sales-person. I apologize to any sales staff who are offended to hear this, but…many customers HATE talking to you about anything.

Also, they sell many ebikes to mainstream customers, but…Pedego also has focused advertising to women and older customers. These are two groups that are often overlooked, and Pedego did not miss a single step when faced with this opportunity. Speaking of older customers, their website uses large print. It’s a small feature, but older customers appreciate the small details that show some effort went into the pitch…

Finally, they are part of the increasing number of companies that are providing financing for their products.

$153/month for the City Commuter

$231/month for the Conveyor

$249/month for the Elevate

William Shatner

When the classic “Star Trek” TV series came out in the 1960’s, it was very ground-breaking. By modern standards it may look low-budget and retro (especially the first season), but words can’t describe what a huge hit it was. Famous Canadian actor William Shatner played “Captain Kirk”, and somewhere along the line, he bought a Pedego. Pictures began circulating of various celebrities riding Pedegos, and recently, Pedego signed Shatner to be an official spokes-person.

_________________________

Written by Ron/spinningmagnets, February 2019

TQ used to be called “Clean Mobile”, in case this drive looked familiar to you. But they didn’t just change their name, they also made some improvements, so…here’s what I could find out.

TQ stands for “Technology and Quality”, and it was started in Bavaria (Germany) by Detlef Schneider and Rüdiger Stahl in 1994 (for more details, click here) They are an engineering and design firm that works in aerospace and medical equipment (among other things). At one point, they formed the Clean Mobile company to handle the mid drive ebike system they had designed, and we reported on them here.

The 3rd element eSpire, using a Cleanmobile mid drive

TQ decided that the Cleanmobile division would file for insolvency (after the majority of European bicycle retailers had signed exclusive agreements for the German 250W Bosch drive, found here). They had filed in February of 2012, and it was granted in August of 2012. TQ then changed the ebike drive-systems division name to TQ-Systems.

The Audi Ebike, seen below (for more info, click here), draws a constant stream of attention, but the prototype never went into production. It is beautiful, and it also used the first-gen Cleanmobile drive.

The Audi electric bike prototype, made from carbon fiber, and using the first-gen Cleanmobile mid drive.

Although you can legally use a high-powered system on off-road trails in Europe, the 1400W / 180-Nm Cleanmobile drive had not found any bicycle partners, since the retailers only wanted to experiment with adding an ebike to their lineup that would ALSO apply to the large EU 250W street ebike market. Regardless of their failed first attempt, TQ tried a second time with the bicycle accessories company “Additive”, to make a mild trail bike with a large cargo bag in the central triangle of the frame (for more info, click here).

The 2014 Additive ebike with the 2nd-gen Cleanmobile drive

The second-gen Cleanmobile drive used a dual planetary reduction for a significant 180-Nm of torque. This is the level of power where some riders become concerned about how fast the chains and sprockets wear out. That being said, weaker mid drives cannot accomplish the jobs that a 180-Nm mid drive can do, so any extra wear that occurs is because the rider is applying heavy loads to this drive.

What I mean is that…if you ride easy trails, you don’t need this much torque, but if you ride on trails that need this much torque, then you don’t don’t care about replacing the chain and sprockets more often, because no other drive can survive what you do.

The Third Generation TQ Drive

This new 3rd-gen TQ drive swapped the dual planetary reduction for a single Cycloidal reduction (see below). And due to the significant 180-Nm of torque on the previous version, I suspect the 2nd-gen motor would eat through batteries pretty fast.

TQ-Systems chose a single Cycloidal reduction for the third-gen system. We reported on cycloidal drives when we first saw the Tangent Ascent mid drive (for more info, click here)  Dave at Tangent chose the cycloidal reduction because it is currently the most compact and light reduction possible. It allows an unusually high reduction within the allowable space.

The TQ-Systems 3rd generation drive motor

Here is a link to our reference list of factory mid drives. And also, here is a link to a comparison of off-road motor systems from emtb-news.de I am listing the common 2018 drives below, alongside how much wheel-torque they provide.

60-Nm, Panasonic 36V 250W

70-Nm, Shimano STEPS, 36V 250W (for more info, click here)

75-Nm, Bosch Turbo (click here)

80-Nm, Yamaha 36V 250W

90-Nm, Brose 36V 250W (for more info, click here)

120-Nm, TQ HPR 120S

160-Nm, Bafang Ultra Max (to see our article, click here)

An exploded graphic of the drive system from the TQ website

The arrangement of the major components inside the TQ drive

The controller is bonded to the left-side aluminum case cover, and that makes the entire drive-case a heat-sink. If it is mounted in an aluminum frame, then the entire frame of the bike draws heat away from the motor and controller.

The TQ motor display from Eurobike 2018.

The Haibike battery pack can be replaced through an access plate at the bottom of the frame.

The Cycloidal RPM Reduction

We have previously reported on the cycloidal reduction found on the Tangent Ascent mid drive (for pics and details, click here). Notice that the inner ring has ONE LESS TOOTH than the outer ring? The motor drives an eccentric in the center, and one revolution of the motor shaft (and it’s eccentric) causes the outer ring to advance a distance of one tooth. The outer ring shown below has 40T.

The 40:1 cycloidal reduction from a Tangent Ascent

I’ve circled the cycloidal reduction teeth in the TQ drive. It appears they use a stack of laser-cut discs.

“…The electric motor drives an elliptical roller bearing. The oval contour moves 150 pins in a wave pattern between the inner gear (148 teeth) and the stationary external gear (152 teeth). The pins act as transmitters. Transmission takes place between the rotary motion of the bearing (input: motor) and the internal gear (output to the chain ring). All the pins are engaged around the entire circumference achieving power transmission that occurs in a minimum of installation space. The transmission gears down in only one stage with a ratio of 37:1. That is, at a pedaling frequency of 80 rpm, the electric machine is running at about 3000 rpm…“

They have toned-down their design from 180-Nm to the current 120-Nm, which would extend their battery range, and help the internal parts last many more years than the previous model. Even so, it is almost twice the wheel-torque compared to the common 75-Nm Bosch unit.

Brands with the TQ drive

The model that was advertised hard at the 2018 Interbike meet in Reno was the Haibike version.

The Haibike with a TQ motor at Interbike 2018 in Reno

The Spitzing M1, made of carbon fiber in Germany…and…don’t ask what it costs.

MG Bike, from Croatia

MG Bike can be found at (click here). They are based in Croatia, and the frame is carbon fiber…

From what we can tell on the TQ website, it seems these motors will come in 250-Watt, 500W and 920W configurations from the factory. But these may simply be software limitations to fit market regulations in the countries they will be marketed in.

Here is a slick 6-minute video of the Haibike and TQ drive in action.

Written by Ron/spinningmagnets, January 2019

This German ebike has an elegant and subtle style that caught my eye. Style may not be hugely important to most people, but I think that this time, it’s worth mentioning. The mid drive it uses is only a mild EU street-legal system, and here is what I could find out about it.

Milos Jovanovic, the designer 

When I’m in the mood for an adult beverage, I’m much more likely to have a beer to drink, instead of wine. That being said…in spite of how I observe the expensive art culture with amusement from a distance, I also appreciate that…sometimes…a slight improvement in how something looks might not be a horrible thing, when you are considering the possibility of using a professional designer…

Milos Jovanovic, and…on the right is a lamp that he designed.

 

Milos is one of many designers working at the “Behance” design studio in Germany. Sometimes they might change the appearance of an existing product, and other times they might be contracted to design the advertising art, or possibly the packaging. (click here to see samples of their previous work).

Milos: “I am a product designer and have been working in this field for over 6 years. I started my career as a freelance designer in Serbia and have worked for companies worldwide. Later I joined Team Design Belgrade, where I worked as a product designer and CAD modeler. I created CycleElectric as my personal project, which was later developed into today’s series product, and it has participated in numerous international design competitions. In Boston, I was awarded first prize for my wood frame design” December 2017

The Cycle electric assembly factory is in Hartmannsdorf, in western central Germany. If you speak German, their website can be found by clicking here.

 

This bicycle from Milos was named “Woody”, and although it might not seem to be dramatically different from existing similar frames, it provided a vehicle for him to begin expressing his passion for bicycle design.

 

An artsy ad for the Cycle electric Komsa

Another artsy ad for the Cycle electric Komsa

The two pictures above are not about how this ebike works…AT ALL. They are advertisements that highlight the “lifestyle” that the ad agency wants to convey to a certain demographic of potential customers. The male model shown might not have EVER ridden an ebike in his life.

In one ad, he is wearing a suit, so…he is a professional that makes a good salary, but…in the next ad he is wearing middle-class weekend casual clothes made from cotton. He is slim (athletic?), but well-groomed, wearing a short scruffy vacation beard, with just a “touch” of grey in his hair.

Also notice the careful use of light and shadows. Plus the varied textures by using leather shoes, cotton jeans, a light wool business suit, brick, stone, concrete, and cobblestones. As much as every little detail in these two ads has been carefully contrived and set-up for the camera…I have to admit that the average ebike retailer could learn a thing or two from these guys about how the compose the main sales image that their website is using on their homepage.

The Drive System

The Komsa uses the TranzX M25 GTS mid drive. This drive can be programmed to provide 500W, but the Komsa has the amps de-rated to 250W in order to make it street-legal in the majority of European nations (Switzerland and Austria allow 500W…gee, thanks!).

The TranzX M25 mid drive. The Komsa also has fold-down pedals for carrying and storage. I have “pop off” pedals, and I like them a lot.

In this form, it provides a mild 50-Nm of torque. It also uses an internal torque-sensor to determine when and how much power to apply (based on user-programmed preferences). EU laws are designed to encourage riders to keep their hands on the hand-grips and available for using the brakes, so…some type of Pedal-Assist-Sensor / PAS is strongly encouraged. Hand-throttles are rare, and in many places over there…they are illegal.

A speed-sensing PAS is simply an affordable disc with several embedded magnets that pass by a movement sensor. Critics of the speed-sensing type do not like how the power application can be slightly delayed and then abruptly on, along with a somewhat flat power curve. A torque-sensing PAS has an instant response to the slightest pedal movement, and they can even tell how hard you are pedaling, so…the harder you pedal, the more power it will apply.

The Komsa uses a Gates belt. These belts never need to to be oiled (like a chain), and they run as silently as it is physically possible to drive a bike…

The Shimano Nexus 8-speed IGH, notice that the insides of the stays are a dark color for contrast.

One of the subtle features of the Komsa is that the “chain stay” is located above the top run of the belt. This is called an “elevated stay” and it makes replacing a worn belt (or chain) quite easy. Chains can normally be broken and slipped out of any style of frame. As far as belts are concerned, a common “diamond” shaped frame must have some type of “frame break” included so that it can be unbolted to allow the one-piece belt to be slipped-in.

The completely-outfitted 6061-Aluminum frame is only 24.6-kg (55-lb). The brakes are both hydraulic-caliper disc-brakes from Tektro, which is an excellent choice. The suspension seat-post is a Satori ET2. The wheels use 28-inch hybrid rims.

The Komsa uses an Internally-Geared-Hub / IGH. They provide an uncluttered look, along with several performance features. The gears are completely encased and bathed in lube, so they don’t need to be cleaned and oiled like external gears with a common derailleur. Also, if you come to a stop in high gear, you can change down to low gear quite easily without the bike moving. With a derailleur, the wheel must be spinning to change gears, so forgetting to downshift before stopping can make for an awkward re-start (You can read all about IGH’s in our article by clicking here).

The integrated 36V downtube battery.

This is no hot rod, but since the lack of a hand-throttle forces you to pedal (whether you want to or not), you can get a decent amount of range from the modest battery pack, which provides 36V and 11.2-Ah, for a total of 400 Watt-Hours of energy. This battery pack model is the TranzX BL18.

Here is a quick four-minute German video

Let’s wrap it up

There are similar frames (with more power) like the Izip E3 Dash ($2300 and 500W, click here). This is relevant because most of our readers are in North America, and I doubt any US dealers will carry the Komsa. The price at this months exchange rate is $2950 in Yankee dollars (or € 2,599 in EU monopoly money).

The bike I currently ride the most is a stretch cruiser with a comfortable riding position. It has disc brakes, fat tires, and a 1500W BBSHD mid drive from Luna Cycles. I could have saved several hundred dollars by getting a generic frame, but I love the curves of the Electra Lux beach cruiser. I am making this confession so you’ll understand that I “get it” when a buyer pays more to buy a certain product simply because…they like it.

The slim downtube battery and small mid drive motor make this model very light and stealthy (if that’s something that’s important to you). The paint job seems to frame the main color with a black edging. I like it, and I may copy that in the future. Couple that with the elevated stay, and there’s just something about this combination that is more intriguing than it should be.

You can’t buy them here, plus they are low-powered and expensive. However, I thought you would enjoy reading about this new model, so…have fun and ride safe, my friends…

Written by Ron/spinningmagnets, February 2019

This isn’t an electric bike, but cargobikes are one of the best platforms for building an ebike. They have always been expensive, and this new contender is the most affordable one I’ve seen so far.

Why?

I can’t think of one instance when I wrote about a non-electric bicycle for electricbike.com before this. We have written on occasion on factory turn-key ebikes (Bafang Ultra, TQ-Clean Mobile, etc) and we have definitely written about kits (BBS02, BBSHD, TSDZ2, etc), so the casual reader can be forgiven for wondering what our focus is.

If I find a new ebike that I think our readers would be interested in, I check to see what information is available about it. First, I want to see if there is even enough info available to make it worth writing about, but also…to see if other web-magazines have already written about a given model. I have a full-time job, so why spend some of my spare time writing about something that already has ten articles about it out there?

So…I’m writing about this new cargo-bike because it is the most affordable longtail cargo-bike to add a kit to.

The 2019 Mongoose Envoy. Kickstands with two legs are awesome!.

Kits are selling well, but there is a surprising lack of advertising about them (compared to the media push for factory ebikes). For me, there are two huge benefits to a kit. First, they allow you to choose the bike frame in a style and size that fits you, and which also fits the job you plan to give your ebike (most factory ebikes have a limited selection of frames). Secondly, using a kit can save a builder a LOT of money, along with providing a much higher amount of performance (the vast majority of factory ebikes are expensive and weak).

So, you’ve decided to get a kit (my most-ridden ebike uses a stealthy 52V BBSHD kit @ 1500W, from Luna Cycles in Southern California), and now…you need to choose a frame to put it on. If you like off-road riding, then obviously, you’ll choose a full suspension frame for taking jumps (although many off-roaders still like a hard-tail downhill frame with a long-suspension fork). Many ebikes ride on streets (like me), and I don’t really like to go super fast. I often cruise at 20-MPH and sometimes peak at 30-MPH to avoid getting killed by a 3,000-lb car with a texting driver.

My medium-speeds and my upright posture means that I don’t really “need” a suspension fork, but I do have 3-inch mid-fat tires and a suspension seat-post, to smooth things out. The aluminum-frame Electra Lux Fat 7D that I often ride is a stretch cruiser, but…it is about $700, and the new Envoy is only about $500.

The Specs

There are dozens of specifications about this particular model, but only a few that I feel are important to us. The frame is aluminum to save weight, and many customers appreciate that kind of thing when we’re talking about a bike-frame that’s this large. The fork is made of steel for strength, and this frame comes in two sizes.

The 2019 Mongoose Envoy

The front gear-set in the bottom bracket is a 3-speed derailleur. That is good news, because that means the chain-stays of this frame are set far enough back that an ebike kit with a large chainring will fit (if you want).

The stock frame can fit tires that are 2.4-inches wide, which allows the popular Hookworms, Crazy Bobs, and CST Cyclops (for the street). The front brake is only a basic 160mm diameter disc brake. That is adequate for an unpowered cargobike, but I recommend an upgrade for electrifying it (click here).

Since the Envoy comes with disc brakes from the factory, it is easy to upgrade them. You might consider swapping to hydraulic calipers to add more clamping force, or adding the adapter that moves the caliper farther out so you can swap-in a larger 180mm or 203mm disc.

The seatpost on the larger size of frame (two sizes of frame) is 31.6mm in diameter, and my best advice for the first accessory is to get a suspension seat-post, you won’t regret it. I also recommend a left-side mirror, but of course there are a dozen other accessory decisions you’ll need to make, based on what you will be doing with your particular ebike…

The gear-set on the rear wheel is an 8-speed freehub cassette. If you decide to use a powerful mid-drive, you may only need 8-speeds, so the front derailleur could be removed to de-clutter it a bit.

The Cargo Rack

The cargo-bags are the main reason to get a cargobike. They add a level of convenience that most riders may not appreciate until they have one to test-ride for a while.

My grandson  on a custom-built toddler seat.

In the pic above, my grandson is on a toddler seat I built, but…more grandkids want to ride, so I’ll need a seat on the back. That means I’ll be riding a cargo bike soon. I don’t know what existing toddler seats will bolt to the rear of the Envoy cargo-system, but I’l be looking into that.

Of course they are convenient for stowing a couple bags of groceries, but I also appreciate using them for storing my helmet and gloves (along with a basic tool set), so I never have to go looking for them when it’s time to ride.

The 2019 Mongoose Envoy

The 2019 Mongoose Envoy

Mid Drive, or Hub Motor?

This frame uses a 68mm wide bottom bracket, with a common Shimano-style of cartridge. This means there should be no problem using the popular BBS02, BBSHD, and TSDZ2 (among others). The TSDZ2 is maxed-out at 750W if you are using a 52V battery, but it has a very smooth torque-sensor, if you like that kind of thing.

Many mid drive motors have a poor heat-shedding path, so we have recommended in the past that within the options available…you should raise the volts, and lower the heat-causing amps. The BBS02 can use 52V, and in that configuration, it has been successfully run at 1,000W. There’s nothing wrong with using only 48V on the TSDZ2 or BBS02, but…every little bit helps.

The unusually popular Bafang BBSHD, shown with the stock sprocket.

However…if you value my opinion, my favorite drive is the one that I ride the most, the 52V BBSHD at 1500W. I also recommend a smaller chainring as the best upgrade. Doing that does lower the top-speed, but it also improves the hill-climbing torque, which is important on a fully-loaded cargo-bike. The stock chainring has 52 teeth (the heavy steel “Frisbee of death” seen above), but I went completely in the other direction with an aluminum 30T. Of course, there are also several other sizes for any performance range that fits your needs.

But…what if you want the POWER of 2600W (52V X 50A)…or more? At those power levels, chains and sprockets on a mid drive might work, but they will definitely wear out faster than with normal pedaling loads. Not only that, but there are very few mid drives that can survive 2600W+ of heat. That means for high power, you might want to consider a direct drive (DD) hubmotor.

The most popular DD hubmotors have a stator diameter of 205mm. If it was larger than that, then the spokes would have to be shorter, which could cause some problems with breakage due to extreme spoke angles (hitting potholes on a hardtail). The most appropriate DD motors at power levels between 2600W-3500W have a 35mm wide stator, like the Leafbike 1500W and the MXUS 1500W.

For those motors, I recommend a 6-speed megarange freewheel, although a 7-speed should fit.

DD hubmotors can take these sudden and high power loads without damage. However, if you have committed yourself to a plan that uses a DD hubmotor, you can increase the hill-climbing ability and lower the motor heat and controller heat by swapping to a smaller diameter rim. The smallest bicycle rim diameter that does not have too extreme of a spoke-nipple angle is a 24-inch rim. Even then, that is the max when using bicycle rims and spokes. However…if you swap to a moped rim, you have several stronger options.

A 3000W DD hubmotor using a 16-inch moped rim, and a one-cross spoke pattern (equal in size to a 20-inch BMX bicycle rim)

Moped rims are measured like motorcycle rims. A 26-inch bicycle rim is roughly the same diameter as a 19-inch moped rim. But for this discussion, I want to point out that a 16-inch moped rim is the same as a 20-inch bicycle rim. Not only that, but moped TIRES are very heavy-duty (very resistant to flats), and also very affordable. If you swap to a smaller moped wheel, the top speed would go down a proportionate amount, but it will also help the hill-climbing ability of the system, and it will allow the motor to run cooler, even when it is under a heavy load. You can read more about moped rims and tires from our article (click here).

Moped rims are heavier and stronger than bicycle rims, but the reason they allow you to go to such a small diameter is because the spoke holes are angled, unlike bicycle rim spoke holes. However, be aware that moped rims have no allowance to use rim brakes.

If this idea appeals to you, and you will be reducing the height of the tire from 26-inches to 20-inches (a 6-inch difference), then the axle mounts need to be lowered 3-inches. That may initially seem to be a huge headache, but it doesn’t have to be. Powerful hubmotors need two strong torque-arms, so the design of the torque arm can also be the element that lowers the axle height.

Be aware that lowering the axle-height also means you must create a new mount location for the brake caliper. Although, this can be off-set or delayed by using a regenerative braking controller (and you can properly mount the caliper later). “Regen” does not harvest very many watts back into the  battery pack (when slowing down, or on a downhill), but it DOES force the motor to act like a very useful magnetic brake.

Here is one example of thick metal DIY torque-arms. They not only resist the counter-torque of the hubmotor axles, this style also lowers the axle-height a bit. These were prototyped in aluminum, and then later water-jetted in steel.

Here is a quick 2-minute video with the Envoy

There are plenty of customers who will pay extra to get a cargobike that has a factory-installed electric drive system, like Yuba, Luna, Rad Power, Juiced, and others…but…if you want to add an electric kit to an affordable longtail cargobike, the $500 Mongoose Envoy should be one of your top-three options for consideration.

If you liked this article, you may also like…

Joels Yuba Cargobike using Nissan Leaf cells (click here)

Teklektiks dual-motor Yuba Mundo (click here)

Juiced Rider ODK-II Cargobike (click here)

Written by Ron/spinningmagnets, March 2019

Schwinn is now selling Bosch mid-drive ebikes through Amazon, and I’ll tell you why this is news.

Schwinn

I grew up in Southern California, and there was nothing I wanted more as a child than a Schwinn Stingray bicycle. The Christmas morning that I got one was something I’ll never forget. It wasn’t just a possession to store in my room and occasionally show off. It was actual transportation that allowed me to travel a hundred times farther on a Saturday than I could on foot. I even used my bike to ride to a job (in fast food) as soon as I could get one.

In high school, they also dominated the “10-speed” market, with models like the Schwinn Varsity.

This is just a random pic of a single-speed Schwinn Stingray with a coaster brake from the web, but it is just like the one I loved as a child (in the 1960’s, and yes, I am that old).

The Schwinn Bicycle company started in Chicago by a German engineer named Ignaz Schwinn. This was in 1895, and for over 80 years, they were an incredibly dominant force in the US bicycle industry. In the early part of the last century, they were so successful, they bought the “Excelsior” motorcycle company.

In the early 1990’s, increased imports from China drove prices down to a point where they could not survive, so they sold the name in 1992 to a Global corporation called Dorel Industries, which sells them through their Pacific Cycles division. This means modern “Schwinn” bicycles are made in China like just about every other retailer.

This is what large corporations do. Smaller companies innovate, but doing that is risky, and sometimes that can hurt you. However, once in a while someone hits a home run. If a new idea from a small company grows large enough, a huge corporation will notice, and then buy you out.

Selling through Amazon is a bold move. You can’t do that unless you are willing to commit to supplying a large quantity of product on short notice, and that ties up a lot of capital without any guarantee that the sales will be adequate.

However, there are a growing number of customers who trust Amazon. If a product is on Amazon, they feel certain that they will actually receive a product, or…they will get a full refund. Everyone here knows that an electric bike from any supplier will have some issues, so it remains to be seen if customer service problems will hurt this new contender or not.

Schwinn Vantage RXe 650b

The most expensive model is a surprising $3999, and it is a non-suspension model with a 350W Bosch mid drive, and the Shimano 11-speed rear-wheel gear-set, and an aluminum frame. It does have disc brakes. If you are interested in one of these, I would strongly recommend a suspension seat-post.

The Amazon link as of March 2019 can be found by clicking here.

The Schwinn Vantage 650b

If you like this model (the RXe), but find that the price is a bit high, you have the option to order the “FXe” with a milder 250W mid drive, and a medium-sized frame. Making those concessions over the RXe brings the price down to $3499

Schwinn Constance

Most of my riding is on city streets as a commuter (not off-road). My most-ridden ebike is a comfort cruiser with a comfortable posture, so…I like them and recommend them often to anyone who asks.

The Schwinn Constance has a “feet forward” location for the cranks (with an upright posture), which was promoted by the Electra company. They took their popular Townie GO! and swapped-in a Bosch mid drive in 2016 (click here). This Electra model is currently $2099.

Although the Schwinn name is being used for this latest version, It was going to happen sooner or later, so…here it is. I recommend a Thudbuster or Suntour NCX suspension seat-post (click here), but other than that, an electric comfort cruiser is my top daily ebike commuter recommendation.

The Schwinn Constance version is using the 250W Bosch mid-drive, and provides electric assist up to 20-MPH. As of March 2019, it is listed on Amazon at $2100 (click here).

It also uses a common 7-speed derailleur, and disc brakes (I recommend you upgrade the front brakes to a hydraulic caliper, or a larger diameter disc (which requires a re-positioning adapter for the caliper) or…maybe both.

The 2019 Schwinn Constance on Amazon

Schwinn Hubmotors?

There are a few models of geared hubmotors sold on Amazon as of March 2019, but I am not really interested in them. If you limit yourself to 250W-350W of power, then you really need to give the motor a selection of gears.

The “Geared” part of the geared hubmotor description means that for every five times the motor spins, the rear wheel spins once (due to an internal gear-set). As far as hill-climbing is concerned (which is the time you really NEED an electric assist), the geared hubs can be considered a “one speed”, and their ability to shed heat is very weak.

When you mount the motor by the pedals (the bottom bracket), the motor has the use of the gears on the rear wheel. You would have to give up some of the top speed to gain some hill-climbing ability (by shifting to a lower gear), but at least on a mid drive you have that as an option.

To be fair, geared hubs are really great for flat land and maybe some mild hills (you don’t have to be constantly shifting). However, serious hills are best served by a mid drive.

If you are interested in the geared hubmotored ebikes from Schwinn on Amazon, just go to Amazon and search “Schwinn electric bicycle” to get the current line-up.

Schwinn Website

The listings on Amazon are not very helpful with details about the models, they just cover the basics. You may be able to find more info on the Schwinn website, which can be found by clicking here.

Written by Ron/spinningmagnets, March 2019

Last spring the Sur-Ron exploded onto the scene as one of the hottest ebike products the electric bike community had ever seen.

It is fast, it has full suspension, it has a long range, it is ultra reliable and rugged, it is built like a Honda,  it is super slick looking and it has a price that nothing can compare to at that spec level.

One year since the Sur-Ron began sales in the United States Luna Cycle is doing a massive sale, offering Sur-Rons for lower than its ever sold before starting at $3300.

CHECK OUT THE SUR RON SPRING SALE HERE

These prices are especially  amazing especially when you consider that Sur-Ron was one of the products hit early in the year with the 25% tariff penalty for Ebikes because of the trade war between USA and China.

The Sur-Ron comes equipped with a full suspension and at first their was a lot of confusion because the bike was offered by dealers in 3 different configurations: RST,  Fastace and DNM.  To offer name brand double crown forks on  a bike at this price point is pretty unheard of but it did  create a lot of confusion for new buyers on which suspension was best….  Luna Cycle released a video to help new buyers try to sort it out. To make it short… there is not a big difference.  And if you want to see a big suspension improvement it is necessary to spend over $1000 on an upgraded fork like the Fox 40. 

Last summer Sur-Ron added to the confusion by announcing the   X  bike  Mostly the X bike added a sine wave controller for about $500  which was a bit smoother quieter  and more torque than the stock controller…  But it was not a huge upgrade over the original Sur Ron and not worth all the confusion it created.  Many customers waited for the mythic X bike to appear. 

When the X finally arrived at the end of the summer, Matt Richards of Fast ElectricBike Facebook did a great comparison review of the two: 

There was a  Sur-Ron around kicking up a lot of dust when compared to the stock bike.  Late last summer Luna Cycle showed up with their upgraded ASI 8000 hotrodded Sur Ron which used a custom tuned controller and a custom built 96v battery made from Samsung 18650 25rs to show what crazy power this 120 pound bike was capable of.  In reality this bike with its overbuilt chassis and reliable motor and drive line is a hot rodders dream. Luna cycle did a lot of videos of this Hot Rod Surron but here is a good sample: 

Other recent developments regarding upgrades of the Sur Ron  are a belt drive which can significantly quiten the Sur Ron Bike. Luna Cycle will be offering the belt upgrade kits in the near future.

Luna Cycle did  one of its first podcasts dedicated to the Sur-Ron.  In the beginning you can see an ASI powered ASI  Sur-Ron and see how quiet it is: 

This podcast has a lot great info if you have time to watch it….or you can listen to it as a podcast while driving (it is in the itunes store if you search for sur-ron)

There have been many great articles and videos done  by new Sur-Ron owners. 

Our favorite is Mark Kitaoka who was featured in the above podcast. Mark started the Sur Ron Owners Facebook Group and also wrote several amazing articles which feature his hot rodded Sur-Ron and his professional photo skills. 

His latest article documents all the upgrades he has done to his bike including $2000 worth of suspension upgrades:  READ MARKS SUR RON UPGRADE STORY HERE

You can also read Marks Review of the Sur-Ron here.

You can see Mark’s photo tour of Luna here:

Here are some other useful links for new Sur Ron Owners:

Sur Ron Documentation:
https://electricbike.com/…/55116-sur-ron-lightbee-documenta…

Sur Ron Knowledge Base
https://electricbike.com/forum/forum/knowledge-base/surron

It looks like the Summer of 2019 will once again be the Summer of Sur Ron.

His photo tour of Luna Cycles Here

Other links that

This is a new product, but it’s coming from someone we have known for a long time. Paul Daniel was formerly an engineer at Brammo electric motorcycles, and he was racing ebikes back in 2011. He also built a custom ebike that we wrote about back in 2014 (click here).

Sharp readers of electricbike.com might recognize that name from the picture of Paul brazing a custom frame, which is the pic we used as the header for our “40 custom electric bikes” article (click here). So…let’s quit the chatter and get to the kit!

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The Motor

Paul raced the prototype at the Sea Otter Classic in 2017. racing is something that shows that a company is serious. This, way, the designers know exactly how capable the kit is, and where the limits are if it is pushed too hard. This is vital to getting the controller programming dialed-in so you can get the best possible performance and efficiency without any fear of damage.

A quick glance at the pic is all you need, to see that the custom motor case is CNC-machined, the aluminum mounting bracket is water-jetted, and the Electronic Speed Controller (ESC) has a cover that was made on a 3D-printer. These three custom production methods are all a part of “Computer Aided Design” (click here), and they allow a designer to rapidly produce several improving prototypes, instead of waiting for a fabricator in another company to finish making your parts for a design upgrade.

As you can see in the header pic, the secondary chain from the drive output to the bottom bracket is a very strong #415 that is normally used on Kart racers. It has a smaller link than standard bicycle chain, roughly 2/3rds the size, and this allows the sprockets to be smaller while still providing the desired reduction in RPM’s.

Inside the housing, the primary reduction uses planetary gears. Paul chose helical teeth to help the drive remain as quiet as possible. This dual-stage RPM reduction allows the lightweight motor to provide a surprising amount of torque.

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The Freewheel

The additional freewheel of a mid drive allows the motor to drive the wheels, while the pedals are stationary. This is important because if it was a solid connection (like the stock sprocket and crank assembly), the pedals would always be spinning when the motor is on. A rider being in that situation is an issue when the rider is leaned over in a turn, and the pedal on the low-side spins around and hits the ground. A pedal-strike can send the ebike and rider flying, causing an unnecessary injury, or possibly losing a race.

I was very surprised that Paul put the time, money, and effort to develop his own freewheel, when there are several freewheels that are commonly used, and readily available (White-Industries ENO, ACS Crossfire, etc). Paul stated that they liked the impressive Sempu torque-sensing bottom bracket a lot, and no existing freewheel would attach to it (most mid drive freewheels attach to the threaded boss on a BMX pedal arm).

But something else popped-out at me. As long as you are designing a completely new freewheel, the diameter on this one is larger than normal. Most bicycle components are typically designed to be as light and as small as possible. A smaller freewheel would also have slightly less friction. The freewheels I listed above were never designed for electric bicycles. They may have proven over time to be the strongest of the available options (through trial and error), but…they were designed for the 250W legs of an athletic bicyclist.

One of the engineering tidbits I picked up when I researched “Internally Geared Hubs” IGH’s (click here), is that the farther away you locate the pawls from the center of the hub, the stronger the freewheel will be, while still using the same components found in common hubs. Notice in the picture above, the 3D-printed parts are the custom components, but the pawls and springs are off-the-shelf bits (why reinvent the wheel?).

I have no way to prove it just yet (years ago I worked as a tech in the load-testing of aircraft parts, both lifetime endurance load cycling, along with peak loads until failure). But at a casual glance, I suspect that this is likely to be the strongest mid drive freewheel currently available, due mostly to it’s larger diameter. That being said, I am not an engineer, nor do I play one on TV.

This proprietary freewheel is designed to bolt onto a Sempu torque-sensing bottom bracket, while still being the largest diameter that can fit inside a common 104-BCD spider.

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The Battery

Revel is making their own battery packs. The initial reason is because nobody is making one that meets their size and shape requirements. Paul wanted the base-model pack to attach to the common “water bottle” mounts on the downtube of a frame. He also wanted the pack to be reasonably small so it would be light, and would also fit into a variety of frames.

The 36V pack is configured as a handy 10S / 3P using the well-regarded MJ1 cell from LG-Chem is South Korea. This is one of my top-three cells to recommend when asked about building a pack. At 3500-mAh per cell, a 3P size will provide 10.5-Ah of range. Also, the factory rates these at 10A per cell, so you can depend on getting 30A peaks from this pack without overheating the cells. 36V X 30A = 1,000W, and that’s important because of the last feature I want to mention…

This pack is fully potted. That means that all of the components are surrounded by a thermally-conductive and flame-retardant polyurethane, so there is no airspace left in it. This provides the most extreme water-proofing and shock-resistance that is possible. Zero motorcycles was the first manufacturer I can think of to take this bold design move (at 102V nominal), and they have enjoyed great success with it. The Luna Cycles V2 Wolf pack is another example (at 52V). There’s one more ebike battery provider that is potted, but they have requested that I do not mention them.

If you are only drawing 450W from a pack that is capable of 1,000W, then the battery pack will never get hot…

The orange square is a rubberized water-proof cover over the on/off button, and the five white dots are LEDs to indicate the state of charge. Fully potting a pack is a bold move, but this method is the most robust that you can make a pack.

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Revel Propulsion

Pauls initial prototype was designed to be a smooth and intuitive addition to an off-roader, where technical trails sometimes need a precise touch. He also felt that a lightweight road bike would also be a big market for a drive like this. This is why the primary design was focused on a “Pedal Assist Sensor” / PAS (torque-sensing), using using a new unit from Sempu. And to be fair, if you are always pedaling, the battery will last a very long time.

Also, in view of the changing ebike laws, Paul also wanted this first version of his system to be “Class-1” compliant, which can have a few benefits on certain state and federal park trails. Paul and Derek will customize the programming in these kits to match your specified maximum legal speed, which depends on the laws in your location.

As soon as he was in development, a few observers asked for a hand-throttle option. If there is enough demand, Paul mentioned that he may add that feature in the future. Just be aware that if you like to use the hand-throttle most of the time, you will not get the full range that your ebike is capable of.

Revel Propulsion’s home website can be found by clicking here.

Their Facebook page can be found by clicking here.

Paul is from Ashland Oregon, Just over the Northern California border, and you can contact Paul or his business partner Derek at

info@revelpropulsion.com

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Written by Ron/spinningmagnets, July 2019

Last year, Luna Cycles produced a battery pack that was fully potted, and every cell is individually fused. They call it the Wolf pack. This month they have released another pack that is smaller, but still uses those advanced battery design features, which they are calling the Wolf Pup. Let’s take a look.

It was March of 2018 when Luna Cycles revealed a battery pack using their new pack design principles (click here). The size and shape was very similar to the most popular packs. Large enough to have a certain range, but small enough that could fit into a wide variety of frames.

The Luna Wolf pack is available with the Samsung 30Q cell (my personal favorite for ebikes), which is rated as 3.0-Ah per cell, and 15A each. It is also available with the MJ1 cell, From LG-Chem in South Korea. The MJ1 is factory-rated at 3500-mAh per cell, and 10A.

The Wolf pack uses four cells in parallel, so the 30Q pack can provide 60A (which is limited to 50A by the Battery Management System / BMS). The MJ1 version can provide a continuous 40A and a temporary peak of amps that exceeds the 50A BMS that is provided.

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The Wolf “Pup”

Luna Cycles has had some success with their small “Mighty Mini” battery pack, which used the high-amp 30Q cell. By having only 28 cells, this small pack could fit almost anywhere, and it still reliably provided 30A for such popular mid drives as the Bafang BBS02 and BBSHD. I have been very open about how the BBSHD is my favorite ebike kit, and I have ridden literally hundreds of ebikes when I have attended several Interbike conventions…

Some ebike enthusiasts who were exposed to the Mighty Mini have asked…”who would want a pack so small?”, and certainly it is not for everyone. However, nobody else is making a high-amp 52V battery pack this small. Luna Cycles sales of the mighty mini have been surprisingly robust, which suggests that there are many efficient mid-drive kit owners who don’t need a large pack.

Personally, I have been able to get over one mile per amp-hour on my BBSHD cruiser when using only the hand-throttle, with no pedaling added. So the 6.0-Ah Mighty Mini would provide over six miles using the throttle only. If you switch to “Pedal Assist Sensor / PAS”, then you only get motor power while you pedal, so, the range of the battery can be easily doubled, if not more (depending on the PAS setting that you use).

If your normal rides are only 12 miles or less, then the Mighty Mini would be the smallest and least expensive pack that would achieve this.

Which brings us to the Wolf Pup. The success of the Wolf battery pack design is a major shift in the industry, and a great improvement for ebike battery pack buyers. Luna Cycles decided to use this pack architecture to produce the smallest possible pack as an option.

It uses the Samsung 40T cell, which has 4000-mAh per cell, and is rated for 35A per cell. This means that you only need one cell in parallel to achieve 52V and 35A. The Wolf Pup achieves a 14S voltage of 52V with only 14 cells. The stock BBSHD only uses a 30A temporary peak, so when coupled with Wolf Pup, the battery pack will easily run cool, with no damage from heat.

A pack with only 4.0-Ah of range is not for everyone, but there are many situations where it is a very appropriate choice. One benefit is that the Wolf Pup is currently only $249, which is surprisingly affordable, considering that it uses the latest advanced battery pack design, with full potting and individual cell fusing.

Down-hillers use some of the most robust bicycle frames available. They grind up to the top of a hill, and then freewheel down the trail at high speed. By adding a motor, the uphill portion can be a little easier, so they don’t need a huge boost, or a heavy battery. The Wolf Pup is the lightest and most compact 52V battery pack available, and it is also the most affordable.

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Written by Ron/spinningmagnets, August 2019