Wondering if anyone can help out with this. In the process of converting my son's 20" BMX bike to electric (FWD hub motor). The bike is done, but I'm running into issues with my battery pack.
I built a 13S3P pack (all new 21700 cells, three in parallel, then the parallel groupings in series 13 times to achieve 48V). I wired in a BMS that I purchased from Amazon and that's when things seem to have gone sour. The pack is solid, measures 45.5V (each cell was delivered at 3.5V) but the BMS doesn't seem to be functioning correctly, I only measure about 35V from its output. It won't take a charge either.
This is all the instructions included with it, but I believe I followed them to a T. The B- connection @ BMS takes the load from the (-) end of the pack, so should be heavy enough wire to support 30A, checked that box. The C- terminal is the negative output to the load (motor) or input from charger, so the BMS can control input/output from the battery and shut things down if needed (over/under volt, overcurrent, etc.) The P-, according to documentation is only for split units that have an independent charge / output plug, which this unit does not have.
On the balancing ribbon cable, B0 (only black wire) goes to the negative end of the pack (much like B-), then I progressively wire B1-B13 to each positive terminal (of the parallel groups) starting at the negative end of the pack. That used up all 13 wires like it should. I don't think I've done anything wrong, but it's not functioning with the BMS installed.
Possible faulty unit? Or did I miss something? Curious if there's anyone here that's dabbled in these things.
Here's the Amazon listing: https://www.amazon.com/dp/B0FCF9N9JZ. They seem fairly popular, available on Amazon, Aliexpress and from other vendors.
I built a 13S3P pack (all new 21700 cells, three in parallel, then the parallel groupings in series 13 times to achieve 48V). I wired in a BMS that I purchased from Amazon and that's when things seem to have gone sour. The pack is solid, measures 45.5V (each cell was delivered at 3.5V) but the BMS doesn't seem to be functioning correctly, I only measure about 35V from its output. It won't take a charge either.
This is all the instructions included with it, but I believe I followed them to a T. The B- connection @ BMS takes the load from the (-) end of the pack, so should be heavy enough wire to support 30A, checked that box. The C- terminal is the negative output to the load (motor) or input from charger, so the BMS can control input/output from the battery and shut things down if needed (over/under volt, overcurrent, etc.) The P-, according to documentation is only for split units that have an independent charge / output plug, which this unit does not have.
On the balancing ribbon cable, B0 (only black wire) goes to the negative end of the pack (much like B-), then I progressively wire B1-B13 to each positive terminal (of the parallel groups) starting at the negative end of the pack. That used up all 13 wires like it should. I don't think I've done anything wrong, but it's not functioning with the BMS installed.
Possible faulty unit? Or did I miss something? Curious if there's anyone here that's dabbled in these things.
Here's the Amazon listing: https://www.amazon.com/dp/B0FCF9N9JZ. They seem fairly popular, available on Amazon, Aliexpress and from other vendors.
