Storing LiFePO4 batteries

[hummmingbear]

Hey Folks - I have 64 LiFePO4 Eve cells coming my way, but I won't be able to install them for another 3-4months. I need some advice on how I should balance and store them.

Does it make sense to put groups of them in parallel to let them balance? Should I connect a BMS now and let it keep them in balance or is that overkill? I don't have an external battery charger, but I'm open to buying one if it helps keep these batteries at the right SOC.

I'm still unclear if I'm doing 2P8S for a ~24V system or 14S4P for a 48V system. I have an existing inverter setup @ 24v but it might make more sense to go 48V.

Any advice appreciated.

 

[TomC4306]

I wouldn't do anything with them except inspect for shipping damage and voltage. Cells should arrive between 30 and 50% state of charge. ~3.29v.
That also happens to be what you store them at.

 

[hummmingbear]

I wouldn't do anything with them except inspect for shipping damage and voltage. Cells should arrive between 30 and 50% state of charge. ~3.29v.
That also happens to be what you store them at.

I like this answer because it's simple. Yup, I planned to inspect for damage and test the cell voltage. If all I have to do is leave them in a cool and dry place that's great.

 

[Steve_S]

Just think of LFP battery cells like little kids... They do not like too cold or too warm just like persnickety kids. If it's comfortable for YOU then it is comfortable for them. the unconnected cells will keep their voltage a long time and are best stored around 3.200 Volts per cell, factories typically ship them out at 3.300.

 

[joanna_lannie]

3-4 months storage time, can be stored according to 50% SOC, no problem! Because the self-discharge rate of LiFePO4 batteries is about 3% per month. It should be noted that all loads should be disconnected when storing. You can refer to the LiFePO4 battery winterize, which has mentioned related content.

"I'm still unclear if I'm doing 2P8S for a ~24V system or 14S4P for a 48V system. I have an existing inverter setup @ 24v but it might make more sense to go 48V."

This needs to refer to your system requirements. Different voltages mean that your wiring costs and loads are different. It is difficult to give advice.

 

[jpimlott]

A 48 volt nominal system is normal a 16S battery (double 8S 24volt)
The nominal voltage is way off from normal operating voltage (ie 24 volt is almost fully discharged)