lifepo4 series parallel question

[Mickie]

If the manufacturer states that a battery can use 4 in series or 4 in parallel. Would putting them in 2s3p be allowed or thats too much for the bms?

 

[timselectric]

That's fine according to the manufacturer.
But I would never put BMS's in series.

 

[Mickie]

That's fine according to the manufacturer.
But I would never put BMS's in series.

Because of them being at different SOC at times?

 

[cs1234]

Get a balancer for the batteries in series. Don't run them pedal to the metal. Run them more conservatively with more generous cut offs for charging / discharging than you would if you weren't using series batteries. Then it's not really a problem.

 

[Mickie]

I already have the balancer connected and since i have them i havent gone under 75% from over night use . I will be adding more loads tho.

 

[cs1234]

I already have the balancer connected and since i have them i havent gone under 75% from over night use . I will be adding more loads tho.

Just realize they will be more prone to oddness than batteries at your desired voltage vs ones connected in series. A single battery in the series could randomly drop out due to high or low voltage. So far when this has happened in my series sets, it hasn't caused any problems. The high voltage charging disconnects seem to be handled gracefully. Low voltage disconnects don't really matter much either, as once one battery is getting that low, it's probably time for them to all come down anyway.

 

[timselectric]

Because of them being at different SOC at times?

Yes, it's impossible to keep them balanced. Without extra equipment or effort.