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Storing and Discharging LiFePO4 at near freezing?

invento123

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Mar 30, 2021
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So I know CHARGING a LiFePO4 battery at near freezing (40°F) to freezing is a very bad thing and should never be done. However is DISCHARGING a LiFePO4 battery at near freezing (40°F) to freezing bad for them? How about storing them at 40°F or below?

To add on, the batteries in question are 2 100AH LFP batteries out in my shed running some lights and such that I usually only pull around 6 amps out of them, will even this small load damage the batteries if it is say 40°F or below outside?

Final question, I have a 80 watt solar panel mounted on the shed that, in peak daylight really only puts out around 60 watts/4 amps, this means each 100AH battery is only charging at about 2 amps. Again in 40°F or below temperatures, is even this extremely low charge rate bad for the batteries and does it have the possibility to damage them?

Thanks in advance!
 
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Where I come from, water at 40°F is melted, not freezing.
Do you mean cold but 8 degrees above freezing?
Or are you referring to -40°F ?

Here's a data sheet that says discharge OK down to -20C (-4F)
But it recommends 0C or or higher for storage.

 
Where I come from, water at 40°F is melted, not freezing.
Do you mean cold but 8 degrees above freezing?
Or are you referring to -40°F ?

Here's a data sheet that says discharge OK down to -20C (-4F)
But it recommends 0C or or higher for storage.

"Where I come from, water at 40°F is melted, not freezing." Lol. Same here. Meant near zero not sub-zero
 
40F, 4C, is pretty close to the triple-point where you get ice, liquid, vapor. But that's around 10mbar, 1/100 of atmospheric pressure (surface of Mars?)


You can store and use LiFePO4 at 4 degrees C, 40F. But charging has to be at a reduced rate.

From the following charts, looks like charge rate about 0.1C max, vs. 0.5C typically OK at room temperature.
2x 100 Ah in parallel for 200 Ah, up to 20A charge rate should be OK.

 
I need to store a LiFePO4 battery for 9 months inside an unheated cottage in a northern climate where some days in Jan and Feb. the nighttime temperature can go as low as -30C. I have read where the battery will survive best if it is only partially charged to 50-60% vs. fully charged. Please help me with facts , not just opinions or heresay. Thank you.
 
I need to store a LiFePO4 battery for 9 months inside an unheated cottage in a northern climate where some days in Jan and Feb. the nighttime temperature can go as low as -30C. I have read where the battery will survive best if it is only partially charged to 50-60% vs. fully charged. Please help me with facts , not just opinions or heresay. Thank you.
I can't say for 100% certain on whether or not that's a good idea however I left my 2 lifepo4 batteries out in my shed all winter where it got down to -16C and they seem to be working fine, no loss in capacity or anything. I had them charged to 70% capacity and didn't charge or discharge them while they were in storage.

However 9 months is a decent amount of time. Might be a good idea to check on the batteries after 4 or 5 months to make sure they're still charged properly and not bulging or anything
 
Discharging parallel lifepo4 doesnt the energy flow between the batteries after discharge to balance them? Like you pull 100A and one battery draw a litle more than the other. So it balance with the other battery. Shouldnt that count as a charge? Or does it happen so fast it doesnt count?

Im thinking it might be bad in minus celsius?
 
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