Home Forums Truck Camper Adventure Forum Lithium Batteries Reply To: Lithium Batteries

#68391
Phil Patterson
Participant

Much of this depends of what you mean by sub freezing temps…Why??

Typically, even a non-heated lithium battery can be safely discharged as low a -4 dF, so the main constraint has to do more with ‘charging’ which should occur at 32df and above…

I have three 200a/hr LFP’s (in parallel, with two paralleled solar systems), but able to mount all three beneath the dinette…So I don’t really have any experience with internally heating LFP’s – I’d be curious to know if the heater only comes on when charging, or say, whenever the batt drops to below 32 degrees (the latter seems somewhat impractical to me)…Another alternative might be to use an externally heated battery warmer blanket (Amazon) which enables you to control it’s operation…Some LFP’s have a provision that prevents charging at less than 32df…

As far as charging goes, a conventional charger will usually do the trick so long as the voltage doesn’t exceed 14.6v (14.0-14.4v will do just fine, but at a slightly reduced rate), and constant voltage-constant current (CV/CC) is best, with no equalization cycle, and there’s no necessity to float – but if you must float, 13.5v or less (as measured at the battery) is advisable (for longevity)…

For long-term storage, it’s best to isolate battery (I use a dedicated disconnect switch) and reduce the SOC (state of charge) to about 50-55% or so…Parasitic drain for LFP’s is uber low – It’s been reported that Shelf-life SOC often remains within an acceptable level for up to 6 mos or even more…

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