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Discussion Starter · #1 ·
Hi All-

my EV conversion (2004 scion xB) has been on the road since 2013, with a hiatus of a few months for body rebuild and other mostly wear-and-tear maintenance after being hit by a moving truck.

Its been basically fine for several months with the exception of bank faults periodically being thrown by the BMS. I had been blaming this on some aspect of the rebuilt car being different enough to let more noise into the system, and had combatted it with much more attention to line filters and other noise combatting actions in various parts of the car. That seemed to reduce the frequency of faults, but they still happened often enough I don't really trust the car for long trips.

In any case today when I tried to drive it the BMS was reporting bank faults while still plugged into the charging station. This was new. On investigation, the BMS (which is configured for 6 banks of 12 cells each and 2 banks of 14 cells) was only successfully reading the state of the first cell in each bank.

I tried to debug things by unplugging all the bank cables, resetting the BMS head end unit and plugging in banks one at a time. Initially doing this allowed it to correctly read the banks, but within a couple minutes with only 4 banks plugged in it failed in the same manner again. After that I was unable to get it to report any data other than the first cell.

Prior to this failure I have not changed any configuration settings or disassembled/changed any hardware for several months.

Given that the failure is consistent across banks which should not have any impact on each other, it looks to me like the head end board has developed a problem.

Has anybody else had a similar experience?

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