3D Printed Weldless Modular 21700 Battery E-Bike

thingiverse

https://youtu.be/aqxTz8gZsiQ?t=138 https://imgur.com/a/IIjZXbg Brief overview of the project at the above video. More info to come, but if you are interested in the project here is a brief explanation on how I put it together, and the parts I used: I advise you not to build this as its probably a major fire hazard, you have been warned. 13S 4P 19.4AH 21700 cell battery, I used Tesla cells recycled from units with bad BMS's that I got from BatteryHookup, the cells are new as far as I know. I designed these caps so that you can slide nickel strip into them, clip the caps together into the configuration you want, and bend the nickel strip to lock it in place. The caps have a bump in them so when you press fit the cells, the bump forces the nickel to contact the cell. Before press fitting, I soldered the BMS leads and the +/- leads to the nickel strip. I fit the cells in one side of the caps, and put the spacers between them. Then I put the other layer of caps on the other side of the cells. After press fitting, I carefully wrapped the battery in a ton of high temp tape to make sure theres no chance I touch the nickel strips or they get pushed in a way that makes them short. After this, I put threaded rod through each of the spacers and used a combination of 3D printed and nylon washers , and lock nuts to tcarefully tighten the 3D printed caps onto the cells. It was important to use a Smart BMS for this project, as I have been able to make sure that the cells are not going out of balance, originally I used a different method to fit the caps onto the cells and it was not effective, so I switched to threaded rod. This, in combination with thick foam wrapping the battery and heat shrink to hold it together, has lasted over 200KM on my ebike, many of which on bumpy trails, without going out of balance due to loose connections. The Smart BMS I used is this one: https://www.aliexpress.com/item/4000825934957.html 13S 40A with bluetooth module. My ebike kit is from e-bikeling 1200W, I pull 24AMPS with the controller, there are no spec sheets for the batteries but they have not heated up more than a degree or two from heavy use. I estimate a 100KM range on the battery.