Gel batteries with solar array charging problems-please help!

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  • Kirkbrook
    Junior Member
    • Dec 2015
    • 1

    Gel batteries with solar array charging problems-please help!

    Hi, we are a totally off grid new farm.
    We are trying to charge a 12600ah gel battery bank with a 30amp mppt charger, from a solar array. We are having problems with charging the batteries, can anyone tell me if I am right in thinking that if that charger is running at 30amps and so are the batteries the charge will not increase in the batteries as they are both even. The batteries charge up to around 24.1 but go no higher. Thanks in advance!
  • Sunking
    Solar Fanatic
    • Feb 2010
    • 23301

    #2
    Originally posted by Kirkbrook
    We are trying to charge a 12600ah gel battery bank with a 30amp mppt charger, from a solar array.
    This has to be a Typo. 12,600 AH?

    I can only assume you mean 2 -12 volt 600 AH batteries in series making a 24 volt 600 AH battery. That being said gel batteries are not suitable for solar. Secondly even if they could be used, there is no way you have enough panel wattage to charge a 24 volt 600 AH battery.

    If you actually used a PWM controller it would take 2000 watts with a 60 amp controller, If using MPPT controller would take 1400 watts with a 60 amp controller.

    Bottom line is who ever designed this had no fricking clue what they were doing and know you have a mess on your hands as it is grossly undersized using the wrong battery type.
    MSEE, PE

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    • Living Large
      Solar Fanatic
      • Nov 2014
      • 910

      #3
      Originally posted by Kirkbrook
      Hi, we are a totally off grid new farm.
      We are trying to charge a 12600ah gel battery bank with a 30amp mppt charger, from a solar array. We are having problems with charging the batteries, can anyone tell me if I am right in thinking that if that charger is running at 30amps and so are the batteries the charge will not increase in the batteries as they are both even. The batteries charge up to around 24.1 but go no higher. Thanks in advance!
      I am not sure, but it sounds like you are suggesting the charge current is 30A, and the batteries are "running at 30A", so they kind of even each other out. It doesn't work that way - that would be voltage, not current. For example, you connect two 12V batteries in parallel when they are at 12.602 volts each, and no current flows from one to the other because they are at the same voltage (potential). of 12.602 volts afterwards.

      With current, whatever current you are generating into a battery bank is actually sending energy into the batteries at the rate current x voltage. In your example, 363 watts.

      Comment

      • Mike90250
        Moderator
        • May 2009
        • 16020

        #4
        The size of something is very wrong here.
        What is your
        Battery voltage (each battery)
        Battery amp hour rating (each battery)
        Bank voltage (all batterys)
        Bank amp hour rating (all batterys)
        Then we can try to trouble shoot the mess. But if you are actually using GEL batteries (gelled electrolyte) and not AGM (absorbent glass mat)
        You are in for problems.
        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

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

        Comment

        • PNjunction
          Solar Fanatic
          • Jul 2012
          • 2179

          #5
          Originally posted by Kirkbrook
          .. can anyone tell me if I am right in thinking that if that charger is running at 30amps and so are the batteries the charge will not increase in the batteries as they are both even. The batteries charge up to around 24.1 but go no higher. Thanks in advance!
          Your gels need to see 28v for absorb. You won't get there if you have the load on at the same time you are charging. What will happen is that you will stay in absorb endlessly, or the controller will just time out to float.

          Try charging again with no loads.

          This is the best we can do without knowing all the other pertinent info, such as the real ah size - your daily power draw, solar insolation and so forth.

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