e-Bike Battery Trouble

Hi. While I know this isn’t a bike forum, I’m using the same system I use on my longboard.

I’m running a 13S5P setup, using N.E.S.E. modules. The batteries used are 65 Sanyo NCR18650GA’s. I’m using this BMS.

Charger reads that the battery is fully charged. Multimeter reads 50v from both the battery and the XT90 output of the BMS. However, when plugged into my BBS02, the battery is read as near empty and only runs the motor in very short, very small spurts.

Is there anything obviously wrong in my setup? I’ve struggled with this for about a year, so buying a prebuilt battery isn’t out of the question at this point.

EDIT: When plugged into a watt meter, it floats around 30v. When powered, it stays there until the bike shuts off and refuses to turn on again, where the watt meter displays 7v. I suspect a BMS issue, and will try to post a diagram.

Mhhhh… You have a 13s battery, so it should be full at 54,6v, not at “only” 50v. Do you have a bypassed BMS or does it regulate the output? And whats a BBS02?

Its a popular mid drive motor from bafang with integrated ESC that can fit many different kinds of bike frames.

the battery and BMS likely has a problem, maybe a group of cell is dead, or the welds are brobken, or the balance leads are broken.

After charging the battery, it seemed to reset the BMS allowing the motor to go. Upon disassembling a battery after some riding around discharging, I noticed a group of cells was scolding hot. I immediately removed the group and placed it in a safe area. I suspect that group was causing the issues and I’ll be replacing that group.