Often times, e-bikes seek to build the biggest battery with the most range. But what if you want to take a couple lunch loops on your bike and only need 20 minutes of charge? That’s [Seth] from Berm Peak set out to find out with his minuscule Bermacell battery.
The battery is made from only 14 18650s, this tiny 52V batty is nearly as small an e-bike battery as can be made. Each cell is 3000 mAh making a total battery capacity of 156 Wh. All the cells were welded in series with an off the shelf BMS and everything was neatly packaged in an over-sized 3D printed 9V battery case. [Seth] plans to make another smaller battery with less then 100 Wh of capacity so he can take it on a plane, so stay tuned for more coverage!
[Seth] hooked up the Bermacell to the Bimotal e-bike conversion system on his trail bike and hit Kanuga bike park. He got three laps out of the Bermacell, and thinks a fourth is possible with more conservative throttle usage. The three laps equates to about 1500 ft of total elevation gain, a metric commonly used by mountain bikers. For a more useful metric for commuters, [Seth] recharged the battery and rode to a nearby coffee shop and back, a distance of nearly 13 miles with pedaling and throttle assist.
This is not the first time we have seen [Seth] hacking on e-bikes. Make sure to check out our coverage of his jailbreak of a pay to ride e-bike.
The TSDZ2 with open-source firmware can run on packs as low as 24V, so you could use only 7 cells, or something only slightly larger than the common power-tool battery. I wouldn’t bet on it being very useful (the motors expect 36-48V), but I don’t think this was the point here :)
Posted 2 weeks ago to YouTube so he should probably expect a registered letter with a C&D from the IP lawyers at Berkshire Hathaway any day now.
They own Duracell.
Normally, as a lawyer who works with makers (but NOT an IP lawyer), I’d say “who cares, it’s a hobby thing, ‘confusion or dilution’ is a stupid worry. BUT this guy has 1.2 M followers.
And yeah, IP law is mostly idiotic — I’m guessing a C&D for this guy while OpenAI gets billions to steal real individual work … late stage capitalism … whatever the ‘f that is …
Go touch the grass.
I have a little Brompton fold-up bicycle that I DIY converted to an electric bike, and it uses a power tool battery, albeit a 36V one (I swap the battery between bike and lawnmower). No charger issues as I already had one. I haven’t taken it on a flight but I have taken it on trains and stored it in the gap between seat backs.
There are a few technical benefits to this idea, especially if you use multiple of the packs in parallel.
One major benefit is granular control of the battery management. A single bad cell can’t stop you, and may be eaiser to repair. But at the very least you can replace one smaller pack instead of a larger pack with teamed series cells.
The 100 Wh isn’t as bad as you might think if you are allowed multiple batteries.
Check out what Dennis Palatov is doing with his AWD EV project and Cascadia Motion. Similar concept with multiple small higher voltage packs, added in parallel until it can supply just what’s needed to reach your performance or range needs.
Also he could take the same idea and move up to a 21700 cell, which isn’t that much bigger (IE would probably still fit) but could carry more power.
I could be wrong, but he may need to move to pouch cells to get the highest power density, at which point making the BMS/Protection circuit smaller and designing a sturdy case to keep them compressed under high draw would probably be your biggest problems.
Excellent hack BTW 👍🏼