u/Good_Echo1715

Hi, I'm looking for some guidance here. I have an S3 that will not charge or turn on (when the charger is connected, the dot matrix display briefly showed the charging symbol and then briefly showed Err6.

I removed the battery module, scraped off the conformal coating over the test points, and observed the following

  • No continuity across fuse terminals
  • Total pack voltage = 38.59V
  • No consistent voltage across discharge terminals (it discharges from ~20V downwards when I probe it with a Fluke 87V)
  • Individual cell voltages all in the 3.861V +/- 0.001V range with the exception of one cell at 3.838V
  • No voltage between VCC and GND on the debug pads on the PCB
    • I was going to try and communicate with the 3.3V UART via vanmoof-battery-tool, but I am guessing this would be a waste of time if the logic voltages aren't coming up..
  • No scorch marks or visually burned components on the board

I replaced the fuse with a SK-4045A from AliExpress (I only read about the Eaton drop-in replacement today!), confirmed continuity, and attempted to reset the BMS by shorting GND and RST for 10seconds.

I replaced the battery into the bike and performed a system reset, but observed the same thing I initially observed (no charging, briefly an Err6 showed). The fuse is still intact though.

I am suspicious that I'm not seeing a logic voltage Vcc, and suspicious of the cell that is 20mV low, but could use some guidance from the experts here.

FWIW, I've owned this bike for 5 years and have had the battery replaced once (under warranty) ~1.5y ago, and fixed the e-shifter into 3rd gear when that broke. This has been an extremely frustrating bike to own, but I would like to resuscitate it if I can.

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u/Good_Echo1715 — 15 days ago