This documentation is still very early and not complete nor well written.
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Discharge phase

We faced a problem during the discharge phase.
The battery discharged at 15A from 41.279999V to 32.040001V for 29mn until it gets too hot and triggers cellsOvertempInDischarge. Some cells were over 75°C.
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One reason why COTD was triggered is 1 screw was missing at the back of the pack, after a diagnosis we see Cell 6 with inner a 0.2V delta between their 3 inner cells.
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We indeed see Cell 5 (Cell 6 of the pack) getting unbalanced a lot because of the bad contact with the pack.

After transition to Error state, battery says the FETS are open but we still see current drained from the battery:
All Fets are 0, but Battery current is 14.82A.
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We then see within 20s the MOS temperature going from 64.85°C to 107.85°C.
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Detailed logs
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Resistance R38 was 1MΩ instead of 2.55kΩ which caused the MOS to get out of SOA.

Cell voltages after 2h rest

Charge phase

After manually balancing all cells, we charged the battery.
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FSM events
We get this very weird 0V / 6V cell voltage. Knowing that:
  • The battery didn’t move an inch.
  • The screws held the battery well.
It really looks like a mechanic bug (as when you weakly screw a devkit and cell contact is bad)
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FSM events
We observe 3 errors:
  • BQ balancing stop multiple times
    • It stops 2 times because of a COV alert
    • It stops many other times (repetitively at 4k seconds) because of Battery IC too high temperature.
  • Charge is leaved when cells are still unbalanced.
    • Battery is in charge-and-balance state
    • One cell is at 4.1V, all others are at 4.2V
    • Charger stops giving current
    • Charge is exited but cells are still balancing.