• [WB4SON] Update on 8+ year old 60 AH LiFePO4

    From WB4SON via rec.radio.amateur.modera@21:1/5 to All on Mon Jul 19 12:10:30 2021
    XPost: rec.radio.amateur.moderated

    WB4SON

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    Update on 8+ year old 60 AH LiFePO4

    Posted: 18 Jul 2021 01:15 PM PDT
    https://wb4son.com/wpblog/?p=4492


    In April of 2013, I purchased parts to build my own 60 AH LiFePO4 battery.  Back then it cost about $440 about $100 more than a comparable battery can
    be purchased for today.  That said, it has served me faithfully for those years, and seems to still be doing just fine.

    I dont use the 60 AH battery often, having discovered much smaller
    batteries better align with my operating style in the wild (why lug a 60AH battery around when you are using less than 3 amps/hour for a POTA activation?).  The last time I charged the battery was October 28, 2018, or 994 days ago.

    LiFePO4 batteries are coulometric efficient, with high efficiency of 99%.  Because of cell balancing circuitry, which tends to bleed off some power,
    in reality, the amount of energy you put in will be a few percent higher
    that what was consumed.

    Today, after recharging the battery, it took 1.08 AH.  So in 994 days of sitting idle, it only lost 1.8% of its capacity.  Thats about 1 mA of discharge per day. Talk about a low self-discharge rate!

    This just confirms one of the many advantages of LiFePO4 batteries you can charge them and leave them sitting for a LONG time and still expect them to
    be useful.  A lead-acid battery left on a shelf for 3 years would be dead flat, and likely unable to be charged to any useful capacity.
    60 AH 4-series LiFePO4 battery, first purchased in April of 2013.

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