Freezing temps and new cells?
- Thread starter S Davis
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FilterGuy
Solar Engineering Consultant - EG4 and Consumers
Since they are not assembled yet, I assume they are not being charged. Consequently, the question is really "what are the allowable storage temperatures."
The specs for min storage temps for LiFePO4 cells vary from about -20C to -40C. (I have never understood why some can be stored colder than others... but each cell has slightly different chemistries so I can believe there are differences)
sunshine_eggo
Happy Breffast!
No. They typically allow discharge operations as low as -20°C.
Lower temperatures also offset the degradation associated with storage at high SoC, i.e., a battery at 100% SoC at freezing will sustain LESS degradation that a 100% SoC battery at 80°F
Lower temperatures also offset the degradation associated with storage at high SoC, i.e., a battery at 100% SoC at freezing will sustain LESS degradation that a 100% SoC battery at 80°F
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
I have seen cell specs that say storage down to -10C but discharge down to -20C..... I have never figured out how that could be, but that is what some of the specs say. (If anyone could explain this I would be grateful)
Discharge warms the cells? I dunno. I would expect the storage temp to be lower than the discharge temp.
RCinFLA
Solar Wizard
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The lowest storage temp for LFP batteries is point of electrolyte freezing and is no higher than -30 degs C. It is usually lower than this with other additives often put in electrolyte. The ethylene carbonate solvent is weak link for freezing temp but with the LiPF6 lithum salt added the EC freezing point is brought down to below -30 degs C. Dimethyl Caronate, also often added to solvent, lowers freezing point more.
Most all Li-Ion batteries use EC for solvent in the electrolyte, with lithium hexafluorophosphate salt (LiPF6). Dimethyl Carbonate, DC is second most common additive.
Most all Li-Ion batteries use EC for solvent in the electrolyte, with lithium hexafluorophosphate salt (LiPF6). Dimethyl Carbonate, DC is second most common additive.
If you expect to encounter sustained temperatures below freezing I recommend adding a system to keep the battery warm.
S Davis
Solar Enthusiast
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I moved them to a heated location until I can start top balancing them.
WYtreasure
It's not happy hour, I'm just like this.
So this makes me wonder about the unheated UPS trucks. Things arrive very cold here these days.
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The traction battery has a heater.
