Verified bad voltage readings from internal BMS, error 19

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Joined: Sun Sep 05, 2021 2:49 pm

Verified bad voltage readings from internal BMS, error 19

Postby Fallingwater Sun Sep 05, 2021 3:13 pm

While riding it, all of a sudden my ES2 slowed down and flashed error 19, then refused to work at all.

M365 Tools showed that one cell group was down to 2 volts and change, and another was at - get this - 6.039 volts (!).

I got home, took it all apart - for the nth time - and checked the battery, whose BMS was flashing red. So I opened it and verified that every group was at around 3.90ish. None was at 2 volts, much less 6.

I reset the BMS and it flashed blue for a while as if everything was fine; I connected it to the controller and it seemed to be behaving. However, before I could put it all back together again, it started misbehaving again in the same way.

I redid the solder joints to the balance connectors just in case, but that changed nothing. Not that I was expecting it to - that 6.039 reading, which never changes by even a millivolt, hints to something worse going on than a simple bad joint. I can't get it to flash blue at all anymore - the fault seems to have gotten worse in time.

I could take the batteries apart and use the cells and a generic BMS to make a 4P deck battery, but before I start such dramatic surgery I'd like to know if this is a known failure mode for the internal BMS and if there's a fix. I'm equipped for SMD soldering, if need be.

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