ETC 277ah 48v pack
JK 2a active balancing BMS.
MPP 7248
Bulk Charge 54.4, float is 53.8v. Pack was top balanced in parallel for a good 2 weeks (3.6v/10a and let it drop to almost 0a draw) before it was put in service.
Been in service a month and going well, but I have noticed 1 cell hitting HVD (3.55v I have it set to) It's cell 2, second after main bat neg.
I assume it just doesn't quite have the capacity of the others so it's hitting full charge earlier. What I am seeing is that cell hitting HVD, charging stops, but the pack keeps balancing as I have balancing kick in from 3.35v, then charging recommences as that 1 cell settles below the recovery voltage (3.45v) and repeat while the other cells catch up.
Cell wire resistances are all almost spot on if that matters.
Aside from replacing that cell, what management strategies are people using? I've lowered the float and widened the balancing voltage window, I was contemplating dropping the bulk charge further also, say 54v bulk, 53.2 float as 53.2 is where the pack likes to settle, but we are coming in to Autumn/Winter here so I'll have less time per day to fill (currently no issues there).
Thoughts welcome as I assume it's not ideal to have that 1 cell bouncing off the top end of its knee constantly.
JK 2a active balancing BMS.
MPP 7248
Bulk Charge 54.4, float is 53.8v. Pack was top balanced in parallel for a good 2 weeks (3.6v/10a and let it drop to almost 0a draw) before it was put in service.
Been in service a month and going well, but I have noticed 1 cell hitting HVD (3.55v I have it set to) It's cell 2, second after main bat neg.
I assume it just doesn't quite have the capacity of the others so it's hitting full charge earlier. What I am seeing is that cell hitting HVD, charging stops, but the pack keeps balancing as I have balancing kick in from 3.35v, then charging recommences as that 1 cell settles below the recovery voltage (3.45v) and repeat while the other cells catch up.
Cell wire resistances are all almost spot on if that matters.
Aside from replacing that cell, what management strategies are people using? I've lowered the float and widened the balancing voltage window, I was contemplating dropping the bulk charge further also, say 54v bulk, 53.2 float as 53.2 is where the pack likes to settle, but we are coming in to Autumn/Winter here so I'll have less time per day to fill (currently no issues there).
Thoughts welcome as I assume it's not ideal to have that 1 cell bouncing off the top end of its knee constantly.
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