diy solar

diy solar

2 identical batteries in parallel, but unequal discharge?

I am considering doing this. I plan to connect two12v packs in parallel, and then, if my 12v inverter ever dies, I may make the switch to 24v by series connecting them. I'm glad you figured it out.
 
Interesting that you bring this up again! I just recently have found the old problem arising at higher loads... When I run a load of 150 amps, one battery gives only 40, ant the other gives 110, tripping its BMS. So now, I'm planning on rebuilding it in a 2p4s configuration with a 200 amp BMS.
I hope your project goes well, let me know how it turns out!
 
Interesting that you bring this up again! I just recently have found the old problem arising at higher loads... When I run a load of 150 amps, one battery gives only 40, ant the other gives 110, tripping its BMS. So now, I'm planning on rebuilding it in a 2p4s configuration with a 200 amp BMS.
I hope your project goes well, let me know how it turns out!
That is a huge current imbalance. There must be a bad connection or a bad cell somewhere. I have 4 strings and they all carry within 5% of each other, with the 2 newer strings pulling a little more than the 2 old strings. Your current balance is nearly 3 to 1. Something is wrong. Can you try running the system on just one battery, limiting power to 50 amps or so? Then check for voltage drops through the system. My guess is there will be a bad connection somewhere. Maybe a buss bar between cells, or even a failing breaker or fuse connection.
 
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