Faulty BMS?

I just plugged in a new BMS to an unbalanced 14s battery, where the groups all have different voltages: 3.8v 3.3v 3.7v ... all the groups have a different voltage from 3.3v to 4.0v, but the batteries within groups are all the same.

I double checked the sequence of the BMS charge wires, and the BMS is acting strange. a row of chips on the charge circuit is going up to 70'C degrees, when it's not plugged into a charger or anything.

Before i noticed the temperature issue, i checked all voltages tried charging it, and the battery terminal voltage went down from 51.5 volts to 50.8v while charging.

What could be causing such weird BMS temperatures and non-charging? it's a new BMS. is there a problem with having groups randomly at 3.3 or 3.9v? will the BMS mulfunction from that?

zzoing said:

What could be causing such weird BMS temperatures and non-charging?

Click to expand...

Reverse polarity? Wrong voltage? (i.e. lithium titanate instead of LiCo)

it's a new BMS. is there a problem with having groups randomly at 3.3 or 3.9v? will the BMS mulfunction from that?

Click to expand...

It will make the BMS work a lot harder, and no BMS is perfect. You are much better off starting with a balanced pack.

Yes you are right. the cell types are marked as 3.2 / 3.6 nominal voltage, and I have 3.2v nominal bms. I made sure that i didn't get a lifepo BMS and i obviously didn't know my chemistry facts well enough back when i bought it. thanks. i'll just have to make a 13s battery until i get a new BMS for it. Thanks.