S/P Nomenclature

A project log for Solar Gas Station

Off-grid solar & battery shed for EV Charging and RV Power.

Bryan WilliamsBryan Williams 01/27/2022 at 04:380 Comments

Just reading some forums, realized I should probably clarify my baseline battery would be called 2P 16S, implying a single 48V battery and BMS, with 2 cells paralleled then strung in series.

Apparently the ? common ? nomenclature would mean 16S 2P would be two 1P 16S batteries in parallel, implying the need for two BMSs, and corresponds to using something like a pre-build off the shelf battery like SoK or EG4. Note the EG4LL 51.2V 100Ah rack mount batteries at Signature Solar et al are rated to be paralleled up to 16 packs -- not sure about others like SoK. 

Also, not sure if Daly Smart BMS 250A model which I have on hand can be paralleled. It would be awkward to build 4P 16S with one BMS as the layout I have planned requires 2 shelves to do that - bus bars and balance leads would be all over the place. Anybody know if you can take two 250A Daly BMS batteries as "2P 16S 2P" ?  

I know series stringing isn't allowed on a lot of 12V batteries because the balance circuits in certain conditions can see the full series voltage, e.g. 48V, while their controller chips can only handle much lower voltages, since they were designed as stand-alone 1S 12V batteries.