15s vs 16s 26650 Cells

[Johnjayjrv]

I harvested a bunch of 26650 cells. They were in a 5s7p configuration and I want to configure them for 48v to charge a bluetti or Delta unit I have. Should I do 15s or 16s? I'm not sure exactly what the difference is so if anyone can give me advice that'd be great.

 

[sunshine_eggo]

Most use 16S to best match typical operating voltages of a 48V lead-acid battery as much of the 48V equipment is designed to operate around those limits. Some LFP manufacturers choose 15S as that's truly a 48V nominal voltage, but that results in ~6% higher current for the same power and ~6% reduced capacity.

 

[Johnjayjrv]

I've seen 48v Lifepo4 chargers that say they are for 16s configurations. Can I use one of those for a 15s configuration? I know the voltage is different, 54.7 vs 58.4.

 

[sunshine_eggo]

I've seen 48v Lifepo4 chargers that say they are for 16s configurations. Can I use one of those for a 15s configuration? I know the voltage is different, 54.7 vs 58.4.

Yes, but you will have to rely on the BMS to terminate charging. Suggest 16S strongly.

 

[Johnjayjrv]

Yeah, I think I'll just stick with 16s. Just gonna be a large pack.

 

[Ampster]

Yeah, I think I'll just stick with 16s. Just gonna be a large pack.

I did not see any mention of the chemistry? There were some assumptions made about LFP chargers. I am just checking the assumption that these cells are LFP?

 

[Johnjayjrv]

I did not see any mention of the chemistry? There were some assumptions made about LFP chargers. I am just checking the assumption that these cells are LFP?

Yes, they are 26650 LifePO4 cells.

 

[Ampster]

Yes, they are 26650 LifePO4 cells.

I agree with earlier posts that a 16S configuration will be easier to find a BMS and a charger. The range of voltages will also be more consistent with charge controllers and inverters.