gillettadam
New Member
- Joined
- Sep 6, 2021
- Messages
- 3
Good afternoon all. I have a Diy solar setup which I installed in December 2021. I am using a Diy lifepo4 pack which is 16s 2p. 280ah grade b cells. The setup is 2 parallel strings each with a daly 16s 200a smart bms. I know this isn't the best way to do this but originally I was going to have 1 string but decided 2 would be better slightly down the road. I top balanced both packs before installing but it looks like I have a potentially large issue in that one battery is operating fine but the other battery is drifting out of balance. This means that the bms is switching off the charge mosfet when the worst cell hits 3.6v this happens at around 54.8v ish. I then have the issue that the pack is no longer being charged but the other pack continues to charge which means the voltage of the 2 packs starts to diverge. As the voltage drops on the high cell the bms allows charge again and then I get a big spike current as string 1 dumps into string 2 which then spikes the worst cell again. Currently the system is performing well and if I hadn't monitored it I wouldn't know there was a problem, but would like to rectify it before it becomes an issue which I'm sure it will.
Would an active balancer help me or do I need to get some new cells and replace the ones that are weak? It does seem 2 of my cells are down on capacity (tested at 265 and 272ah respectively) compared to the rest which tested very close to 280ah. But that's the risk I took with grade b cells so can't really moan about that.
Obviously an active balancer is much cheaper than buying replacement cells so I'd rather do that if I can.
Many thanks in anticipation
Adam G
Would an active balancer help me or do I need to get some new cells and replace the ones that are weak? It does seem 2 of my cells are down on capacity (tested at 265 and 272ah respectively) compared to the rest which tested very close to 280ah. But that's the risk I took with grade b cells so can't really moan about that.
Obviously an active balancer is much cheaper than buying replacement cells so I'd rather do that if I can.
Many thanks in anticipation
Adam G