2p16s: What to do with faster (and slower) 'runners'

[Samcat]

Not sure I would agree here. In photo 5 the cells are discharged and at rest. If there were a poor bus bar connection between the cell pairs 2 and 3, the cell voltage would have recovered with no load. Since the voltage has not recovered, I doubt it’s the bus bar.

You will probably have to take it out test alone for Ah ratings....If all goes well top balance all cells individually and do some detective work why this row is not charging with rest of them or discharging faster than rest of them.

 

[JJJJ]

This is very basic compared to the other responses. However if all else fails consider placing like cells together. There are pros and cons to this approach naturally but it might be worth a try.

 

[Miles B]

I've never liked XpYs configurations.. There seems to be more points of failure than YsXp with multiple BMS. If any of the bus bars in the parallel pairs has a higher resistance connection, you can end up with a badly behaved pair. If any single cell decides to fail short, you're shorting its partner through it, which is very bad news. Each cell of the pair sees potentially different (no pun) resistances in the bus bar network to its partner, as it has an extra bar and extra connection that its partner doesn't share. All this to save a BMS doesn't seem worth it to me. Add to that the mystery that you're now facing.. which of the odd pair is misbehaving and why? With only single cells per channel on the BMS, it's a lot clearer. You also have one point of failure with the BMS and many single points of failure at all of the interconnects in the battery. With YsXp, you've got a backup if one battery or BMS flakes out. You can take a whole battery offline and leave your setup running.