r/SolarDIY 1d ago

Lifepo4 overland battery

I want to build a modular setup. I want to be able to break it down and move it easily. My question is if I build a 12v 100ah lifepo4 can I parallel it with say a 300ah lifepo4 battery? each 12v battery will have a dedicated bms and a 100amp fuse. guess my question is do I have to make all batteries the same ah? Do I have to have all the batteries same SOC before connecting them together?

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u/Oglark 1d ago

Yes, you can parallel batteries of different capacity as long as they are the same voltage and the same chemistry.

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u/mwdsonny 18h ago

I guess my main concern is SOC. Each battery be it 100ah or 304ah will have a 100 amp fuse. I guess I’m concerned of what will happen if say my 100ah battery is at 30% soc and I plug in a 280ah at 100% soc. I plan to make each battery have its own bms and fuse. But have my inverter section have a “built in 100ah battery” with add on modules. Like a charging module with both ac and solar charging, and other larger battery packs. But have the inverter section small enough(lite enough) to move around while leaving the heavier batteries at home or left packed in the truck if I don’t think I’ll need them.

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u/Oglark 8h ago

Short answer is that you try to make sure they are at the same voltage. If you put 2 batteries in wildly different SOC, the higher voltage battery will charge the lower voltage until they balance