Repurposing my 36V Li-Ion ebike battery

[peterjd]

Hi, I have a 3 year old 10Ah 36V ebike battery (from Swytch Mk1 ebike kit) which has developed a short on one of the banks(4 cells) of paralleled 18650 cells. Other banks look ok. Rather than replace those cells, which would be difficult in the middle of the pack and may not anyway be compatible, I would like to bypass the faulty bank with heavy gauge wire, so I can repurpose the battery for a friction drive booster (24-36V) which I use on one of my other bikes. Can I modify the wiring (ie with one less sample points) to the battery management system and do I need to mod the 2A charger. Thank you for any comments.

PS If necessary I can isolate the faulty bank by cutting the welded interconnects.

 

[docw009]

If you bypass the bad row, the BMS will no longer work. I assume you want that to work. You may be able to get a 9S BMS or find a 10S model that works with the tenth row tied off, but either approach means you need to install a new BMS. And where will you find a 9 charger? You'll have to get an adjustable one and crank it down to 38V.

You can run w/o a BMS, Don't recommend it. I had a fairly new battery with a bad BMS. I bypassed it to test something, but got distracted, and next thing I knew, I ran the battery flat. I gotta scrap that battery now.

Fixing it with a new row of cells is possible, but not worth it for a three year old battery.