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Max recommended discharge rate for batteries

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  • Max recommended discharge rate for batteries


    I have 8 Trojan SPRE 06 415 in series for 48V. According to the spec sheet the maximum charge rate should be a tad below 50A (13% of 377 = 49.01), but for discharge rate it only specifies up to C10, which is 34.6A.


    If I have a load that needs more power than that for a short time (eg. 10-15 minutes), will it damage the batteries? Is there a recommended maximum Amp draw?

    I'm new to PV systems and batteries, so I'm a bit lost there.

  • #2
    A short 3 second peak draw, to start a motor or something is not a problem for the battery, but it may be a problem for the wiring to the inverter, depending on the loss involved there.

    More than a minute over the recommended discharge spec, and the battery voltage is likely to quickly sag and cause an inverter fault.
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



    • #3
      I'm taking more about a sustained current draw of a few minutes a bit over the specced max discharge rate, like 10% more. Will that cause any battery damage?


      • #4
        Can you be more specific? like is exact how many amperes DC you talking about? how often this will be? once a while or daily or all the times? if is less than 50 amps and not occur very often. it should be ok. but if the happen all the times you need to increase the battery bank capacity. they recommend 5% of 20 hours discharge rate so the battery have more capacity on the FLA batteries.

        The question also if the voltage will drop bellow the low battery cut off in the inverter setting because the high current draw.

        good luck.