REC Q1 BMS Balancing Question. 2s16p LifePO4 pack

[Sunnytheskoolie]

Hello,

I have a 32 cell pack, 2s16p at 48V and the BMS is heating up at every charge. It gets up to about 53c while it tries to balance the cells.

I have attached screenshots of the settings I have set in the BMS, do you think that the settings are causing the issue?

Sometimes the pack balances alright as you can see in the last screenshots but this only happens when the pack is drawn down to below 60% SOC.

Thanks for the advice.

PS. The cells are Class A Eve 3.2v 260ah. When I received the pack the voltages were almost all the same so I set the whole pack in parallel for a couple of weeks and then assembled it. I didn't bottom balance or put a charge on the pack while it was sitting in parallel.

 

[sunshine_eggo]

Hello,

PS. The cells are Class A Eve 3.2v 260ah. When I received the pack the voltages were almost all the same so I set the whole pack in parallel for a couple of weeks and then assembled it. I didn't bottom balance or put a charge on the pack while it was sitting in parallel.

This does essentially nothing except make sure all the voltages are the same. it makes only negligible differences in states of charge.

"Balance" refers to state of charge, not voltage.

Cells can only be "balanced" at 2.5V (empty, bottom balance) or in the 3.55-3.65V range (full, top balance).

Even batteries with shitty balance will show nearly identical voltages in the flat portion of the voltage curve because that's the nature of LFP.

Begin balance at 3.3 is worthless. Make it 3.4. 3.3 may also mean it will balance even during discharge. You don't want that.

End balance at 3.4 is when you should start. End balance at 3.6 if it allows you. 3.5 if not.

Not sure I understand the end of charge hysteresis, but if it means what I think it does, 0.02 instead of 0.05.