@mm43
Either schottky diodes or power mosfets with reverse current cutoff circuitry.
Yes, cells must match closely.
Charging includes cell voltage balancing by current bypass. Discharge is not balanced.
Questions on my mind (Picture: CT scan of JAL APU bat at BOS)
Cells top left #1, top right #2 to bottom left #7, bottom right #8. #3 was identified by NTSB as shorted (#6 in their rotated picture).
- Why all and only the left cells #1, #3, #5, #7 show similar horizontal "streaks"
- What are physical/chemical differences between left and right cells after strip down
- What is the (expected) effect of these streaks on cell characteristics, such as leakage, capacity, charge current vs cell voltage
- Were similar streaks found in other batteries
- Can streaks be recreated in new cells by electrical or thermal means
- Why cells #2, #6, #8 show more bulging than others
- Was #3 the first cell to fail
- Did failure of #3 induce over charge of other cells
- Did failure of #3 thermally conduct to nearby cells (#1, #4, #5) and cause thermal runaway in any of them
- Which cell valves were found ruptured