lifepo4 and bms battery strange behaviour

[Pattap]

Hi all

My first post so hi to all. I'm relatively new to this subject so forgive me lack of proper terminologies.

I've built a 4s pack out of lifepo4 cells a while back. I have hooked up HIBMS 100A BMS to it. It's been working absolutely fine for over a year. Battery is installed in my van. Charged by solar and dc2dc while driving. I have noticed lately that the bms will only allow to charge when there's load applied. Let's say there's 10amps being drawn and BMS will only allow the battery to be charged with 10amps even if my solar is pushing 20a and dc2dc another 20a.

I've noticed one of the cells is a bit off now and then, by 0.35v. I think my active balancers takes care of it most of the times. I'm still observing this behaviour as it just started happening lately.

This makes the battery stuck at certain SOC.

 

[jonyjoe303]

when charging at high amps, the cell that is off balance is always going to cause the bms to shutdown. What active balancers do you have? I have the qnbbm balancers that handle up to 6 amps, I had a similar problem and been using these balancers for years on my 4s 220ah lifepo4. Without these balancers the charge was stopping too soon. I charge at up to 12 amps with these balancers.
You would only notice the problem when charging at high amps, at lower charge rate, the balancers you have might be able to handle it.

qnbbm balancers