Temperature Question re LFP Batteries

Mountain Don
Mountain Don Solar Expert Posts: 494 ✭✭✭
in General Solar Power Topics #1
This is directed at those who are using LFP batteries....

In normal day to day use do the cells get warm? I am asking as if I was to use these I would need them inside to keep them above freezing in winter. However, we also have a warm 6 to 8 weeks in summer when I would not want them to add much / any heat to the interior. So that is the point of the question. Thanks

Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
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  • Ampster
    Ampster Registered Users Posts: 174 ✭✭✭
    #2
    No mine don't get warm. I only use 20% of the capacity during a normal 10 hour stretch. There is heat produced by the inverter and charger but not from the batteries.
    8 kW Enphase micros AC coupled to a SolArk 12K
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  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    #3
    They don't add any additional heat especially in our application where we are what is called "Sub-C" (very low current relative to the ah capacity of the cells) because our bank is sized appropriately - not to mention insanely low internal resistance. Once you get above about .5 to 1C, then you may notice some. If you ARE doing that kind of charging, then you are using an EV and not a solar housebank. :)


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  • karrak
    karrak Solar Expert Posts: 326 ✭✭✭✭
    #4
    From my battery monitor since I started monitoring power just over a month ago I have had around 74.1 kWh go into the battery, 67.9 kWh has come out and the battery has about 1.5 kWh more charge in it so have lost around 4.7 kWh in around 45 days or around 100Wh per day(4 Watts continuous) which I assume ends up as heat. Gives an overall battery efficiency of around 94%, this includes the power used to run the battery monitoring circuitry.

    Simon
    Off-Grid with LFP (LiFePO4) battery, battery Installed April 2013
    32x90Ah Winston cells 2p16s (48V), MPP Solar PIP5048MS 5kW Inverter/80A MPPT controller/60A charger, 1900W of Solar Panels
    modified BMS based on TI bq769x0 cell monitors.
    Homemade overall system monitoring and power management  https://github.com/simat/BatteryMonitor
     

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  • inMichigan
    inMichigan Registered Users Posts: 51 ✭✭
    #5
    My batteries also don't feel warm to the touch. I generally limit global charging to 0.3C. Four FLEXmax 80's generate the heat (and noise) for my equipment room.
    42 SP-335's (14.1kw) ->   4 FLEXmax 80's /  5kWh using 17 CA100 CALB cells /  FLEXnet DC  /  MATE3  -> 2 Radian GS8048A and watched over by Vantage Pro 2+ PWS all running since 2015
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