How long storing LiFePO4?

[kentdavidge]

I bought four 3.2V 100Ah LiFePO4 cells from Kingbo and they were shipped on March 18. The only test I did so far was to measure the voltage of each cell (it reads 3.2V). Question: how long can I let the cells sit in the box without use, and without damaging them?

 

[chrisski]

I’d recommend charging it first.

If its going to be months in storage, I store my lithiums at 50%.

If its a shorter time, 100% would be fine.

I’d hope the spec sheet gives some good data, but I have found the specs for storage are lacking.

 

[sunshine_eggo]

I bought four 3.2V 100Ah LiFePO4 cells from Kingbo and they were shipped on March 18. The only test I did so far was to measure the voltage of each cell (it reads 3.2V). Question: how long can I let the cells sit in the box without use, and without damaging them?

Measure voltage to X.XX accuracy. Long term resting voltage of about 3.28V is about 30% SoC. I wouldn't let it go much lower than that. Storage between 30 and 70% is the typical recommendation.

You can always add a fixed amount of charge by timing the charge at a constant current, i.e., charging for 1 hour at 10 amps means you've increased the SoC by 10%.

 

[timselectric]

I have 48 cells that I picked up last may.
They are still in the boxes, and I'm not worried.
If they were already built with a BMS connected, that would be a different story.

 

[kentdavidge]

@chrisski "I’d recommend charging it first." --- do you mean with a specific charger? My plan is to charge them via a charge controller (which I have already bought) powered by solar panels (which I just ordered).

 

[42OhmsPA]

Measure voltage to X.XX accuracy. Long term resting voltage of about 3.28V is about 30% SoC. I wouldn't let it go much lower than that. Storage between 30 and 70% is the typical recommendation.

You can always add a fixed amount of charge by timing the charge at a constant current, i.e., charging for 1 hour at 10 amps means you've increased the SoC by 10%.

Thanks for the reminder to check my spares that have been sitting in a box for a few years...

 

[chrisski]

@chrisski "I’d recommend charging it first." --- do you mean with a specific charger? My plan is to charge them via a charge controller (which I have already bought) powered by solar panels (which I just ordered).

Charge controller is fine.

 

[Wattson25]

Those LiFePO4 cells can sit unused for about 6-12 months without damage, as long as they're stored properly. Keep them in a cool, dry place (around 15-25°C) and at about 50-60% charge (3.2V is fine). Check the voltage every few months to make sure they’re not dropping too low.