100ah cells in parallel banks.

[88 Fingers Louie]

Hi,
I’m after some advice on what is the best configuration for 48 x 100ah Lifepo4 cells.
I’ve found a great deal on these cells and this size bank will be ideal for my system.
I’m going for 100ah cells as I’d like the flexibility to pull off 16 for a smaller 48v bank if I need to in the future.

My thought was to run 3 x banks in parallel each with own BMS but I’m unsure how the balancing side of things will fare?
Series- paralleling I’ve done before with smaller 12v systems with the same cells and had no issues but a 48v, 15kw battery is the next level for me.

Cheers

 

[Samsonite801]

Yeah, that is fine to do. I have 32x cells (in 2 parallel 16s banks with 2 respective BMSs per bank), just make sure the BMS supports parallel configuration.

The parallel banks will balance fine on their own (in relation to each other), but some BMS models they say they don't support multiple BMS in parallel bank configuration...

The parallel banks don't even know or care about each other (or shouldn't), but nevertheless some BMS are not supported that way, as someone put it, due to some kind of back feed issue. I think any good quality BMS should be built to not care if there is another adjacent bank sitting on the DC bus, but there are some that explicitly say they don't support it.

JBD 16s should work good for it as others have said they support it (at least that's the style I chose and they passed bench testing, I haven't put mine into full service yet other than testing some charging and discharging on the bench and they seem to work fine, I haven't noticed any problems)...

 

[OffGridInTheCity]

I'm 18650 rather than LifePo4 but I run 6 parallel batteries of 14s100p (260ah) with no problem.


As you point out, if the battery bank is large enough, you have the option of removing 'a battery' to work on it without disrupting the overall system by much.

In addition, I find it 'easy' to add batteries to expand the system - just parallel in a new battery and adjust overall ah / SoC metrics of the system.

Also, there's a physical weight consideration. I couldn't handle 1 battery of 14s600p as each cell would weigh ~60lbs and be awkward to manipulate 14 of them into place. For me, each battery of 14s100p is about 130lbs and comfortable for me to manage.