Are Lithium Batteries the way to go?

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  • EstragonEstragon Posts: 2,607Registered Users ✭✭✭✭
    I'm not sure how cold it gets in Alaska. Here, it can get into the -40s (though not so often in recent years, it seems). My understanding is the batteries are okay in storage at that temp, but can't be charged unless warmed up. It seems to me the solution would be for incoming power, solar or otherwise, to first be used to warm the bank, probably slowly to allow uniform warming.

    The box itself and contained airspace might heat pretty fast, but say there's 1000# of battery needing to go from -25 to +35°f. That's 60° x 1000 =60,000 btu, roughly 20kwh. My 48v string of L16s weighs about that. A lithium bank with equivalent usable power would presumably be less (maybe 1/2 ?), but still tough to warm with a single panel, even in a well insulated box.

    Keeping a bank warm (as opposed to warming a cold one) might be possible, depending on the surface area of the box, ambient conditions, and the Rvalue of the insulation, but I'd count on the panel getting covered by snow, or some other impediment.

    In other words, I'd want a charging system that simply won't charge if battery/cell temp is below spec.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Dave AngeliniDave Angelini Posts: 3,886Solar Expert ✭✭✭✭
    Something like that estragon because one can't depend on keeping a solar array clear to keep a battery warm.
    I just went through this recently and we ended up using an AGM for cost and the least likely to have damage in temps like you mentioned.
    An attended system is not a problem as long as there is a pulse on the human ;)
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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