Keeping lifepo4 batteries in a refrigerator

Yerf
Yerf Registered Users Posts: 65 ✭✭
edited October 2017 in Off Grid Solar & Battery Systems #1
Do you think it's a good idea to keep my off grid lifepo4 batteries in a refrigerator while in use with a thermostat setting of 20c to prolong their life?
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    #2
    For LFP life cycle, I think the difference in 20˚ and 25˚C is minuscule, and not worth the trouble. Although, colder temps would be recommended for storage, maybe 5˚ to 10˚C.
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #3
    I'd do it if the ambient temperature commonly gets up to 35C.

    I am available for custom hardware/firmware development

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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #4
    If the refrigerator is powered by the battery it's cooling then the added load, if left on 24 hours, would probably have a negative effect greater than the benifits gained. If powered seperately, or using only excess energy during the day, then it may help.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #5
    Our temperatures can get upto 45 c outside. So I was thinking of putting them in the garage where it might be 35c at best, not good for the life of the batteries so I hear. So maybe I could use a small chest freezer and only switch it on when I have excess energy.
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #6
    I suspect having them in a fridge would be of some benefit even if the fridge is left turned off, as the insulation would keep the batteries at more like the daily mean temp rather instead of daily max temp. Putting them in a dugout or whatever might be even better, keeping them at more like seasonal or annual mean.
    Off-grid.  
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  • Yerf
    Yerf Registered Users Posts: 65 ✭✭
    #7
    Do they need ventilation?
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #8
    I don't think so, but you'd want enough space for the batteries to disipate the bit of heat they'll generate in operation.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #9
    A good rule of thumb is for every -10C (-18F) decrease in temperature, a 2x longer life (storage life--Cycle life is probably not affected). At 0C, that would be 2x2=4x longer storage life... Conversely +10C increase, 1/2 storage life. Formula works for for just about anything.

    Used to try storing flashlight batteries in fridge decades ago (AAA-D cell alkaline). found that moisture/condensation ruined cells in fridge long before room temperature cells failed.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #10
    If you want battery cooling (more important with lead acid), consider using water that is only cooled while solar is available.

    I am available for custom hardware/firmware development

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