Adding cells

[Djk]

A friend of mine recently gave me a lifepo4 battery he had built but only use for a month or two and project. It’s a 4s 280ah battery with a Daly 100a BMS.

I want to expand the system to 200a 560ah, and I can get cells from the same vendor.

I was wondering whether I should:

A - use the cells to set up another 4s system with its own 100a BMS and running the two in parallel.

B - set up the whole things as a 2p4s with a single new 200a BMS

C - do some thing totally different that I haven’t thought of yet

I’m leaning towards B, since it seems the simplest, but I’ll admit my understanding of battery optimization is next to nil.

Thanks!

 

[Bud Martin]

I go with 'A'.
I myself built two units with the same spec and run them in parallel, so if one fail my system will still be running but at lower capacity until I fix the broken one, and it is also easier for me to deal with the weight.

 

[Struc]

Also go with "A". You'll have to buy another BMS either way, so might as well buy a cheaper one. You'll have a much better chance keeping everything happy in 2 separate packs, plus you get some redundancy out of it.

 

[Djk]

Thanks, that makes a lot of sense

 

[MisterSandals]

You did not say what you will be using the battery to power. Its hard to recommend a "best solution" without that.

If you plan on using a big inverter (more than 2000W), you should strongly consider making an 8S 25.6V battery.