Resting voltages of LifePo 16ah cilindrical cells

[joystix2]

I purchased 16 individual 16ah cells from MM about 3 months ago and made a 48v pack. I have only had about 4 cycles on them and I am getting some disturbing reading on individual cells. After charge and sitting for a few hours most are giving me reading of 3.35-3.36v... But on about 5 of the cells I am getting 3.8-3.9 resting voltage and about 4.2 hot off the charger. Do you think I have got 5 bad cells? Any way of trying to condition them? Look forward to hearing what should do or try...

Thanks
Ric

 

[neptronix]

4.2v hot off the charger!? what kind of charger are you using?

It sounds like those cells are being overcharged, just my guess.
It could be from a bad balance from the factory.
And whatever you are using to balance it is not doing a good job.

 

[frodus]

Did you equalize the cells before you put them in the pack together? (parallel them all and charge with a single cell charger so they're all at the same SOC)

Are you using a BMS?

If you are doing neither, then you should STOP what you're doing and do both. These batteries need to be balanced before putting them in a pack, or have a balancer installed. If you did neither, its no wonder your pack is out of whack.

If it were me, i'd throw a cheap balancer on there.

 

[dogman dan]

Good advice to paralell the cells, and do some break in cycles that way. Then assemble the pack in series configuration.