Battery hot not under load?

[NeedForSpeed]

I just rebuilt a battery, and under no load the BMS is putting out serious heat. I’ve never experienced this, any ideas where this is coming from?

Showing 26 Celsius in room temperature.

Lion battery, LG HG2 cells, bluetooth bms, 20s 10p

 

[NeedForSpeed]

False alarm, for whatever reason the numbers stabilized eventually.

 

[999zip999]

Be careful as that's a lot of stored energy. I would balance before to same voltage before assembly. I not saying full charge just same like 3.8v before BMS hookup.
Do you have any pics of the unrapped pack ?

 

[John in CR]

Since there's obviously something wrong with parallel group cell #10, how could you not investigate that voltage difference even before posting a question here? I have packs that have been in daily service for years without any BMS protection other than myself as the BMS, and none of my packs have ever shown such an out of balance condition.

 

[dogman dan]

If the bms was discharging a high cell group, it would be warm. Or it could be warm because you are charging real fast?

 

[HK12K]

Where did you get those HG2's? A trusted vendor, I hope, as they are one of the most oft counterfeited cells on the planet.

If you crapped out and got fakes it would explain the voltage disparity, and the disparity explains the heat. The BMS is acting like a little space heater as it bleeds down the high groups, and the longer it takes to balance the more heat it will generate.