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  • Newbie question. / battery bank and ac chargers

    I use youtube to checkout others system and to try and learn more. I have seen more then one off grid system with ac battery chargers attached to their battery banks to keep up charge on cloudy days. Is this advisable ? If so , should you charge as a trickle charge or fill charge ?

  • #2
    for small 12V systems, automotive battery chargers will work in a pinch in cloudy weather.

    larger systems use dedicated chargers like golf cart or forklift chargers, and are run from 6-10Kw 240V generators

    Other large systems use a charger function inherent in the main inverter, used as a high amp charger, my inverter, for example, can charge my 48V bank at 100A, given enough generator.

    Just about every system has different needs, and gets the design adjusted to fit best
    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

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    • #3
      Is there an ac charger that would kick in only when battery bank is low and needing help ? It would recognize bank is low and come on automatically ? In other words an ac charging unit meant for this exact purpose for solar banks

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      • #4
        Originally posted by carolinaken View Post
        I have seen more then one off grid system with ac battery chargers attached to their battery banks to keep up charge on cloudy days. Is this advisable ?
        It is a requirement. Solar is not fully capable of fully charging a battery. Additionally FLA batteries require an equalization charge periodically about once a month and an EQ charge can take up to 24 hours. Failure to have a genny is a plan to destroy your batteries and spend a lot of time in the dark.

        Stop watching You Tube idiots.
        Last edited by Sunking; 03-22-2018, 10:01 AM.
        MSEE, PE

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        • #5
          Originally posted by carolinaken View Post
          Is there an ac charger that would kick in only when battery bank is low and needing help ?
          No. You can hard wire a charger with no problems, but you would need to keep the power turned off. Reason is simple. Commercial power is a STIFF SOURCE of power and solar is a soft source. In other words if the AC charger has power, then all power comes from the charger while your solar panels sit there and do nothing except collect dust.

          MSEE, PE

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          • #6
            Even if charger run in 3amp mode ( trickle charge ? )

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            • #7
              Originally posted by carolinaken View Post
              I use youtube to checkout others system and to try and learn more.
              1st error. Suggest you disabuse yourself of the idea that the new "Idiot's Bible" has any other use than as an occasional comedic diversion sort of like late nite TV ads - and taken about as seriously.

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              • #8
                Originally posted by carolinaken View Post
                Even if charger run in 3amp mode ( trickle charge ? )
                The problem is that most devices that determine if the battery voltage is "low" are set below 11 volts which is very low for a deep cycle battery to the point of almost killing it.

                You would need a very intelligent sensing device to measure the voltage at say 12.4 volts and then start up a charger (from some AC power source) to get the battery back up to Full SOC. Or just set up the charger when you manually measure the battery voltage is low or if it is a cloudy dsy.

                I would not rely on something to automatically do this for you if your battery is a critical part of your power supply. An emergency generator that senses the loss of the grid power is a much better investment to keeping power on at the house.

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                • #9
                  THANKS FOR THE INFORMATION.. How often than should I top off my batteries.. every month every other month ?

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                  • #10
                    Originally posted by carolinaken View Post
                    THANKS FOR THE INFORMATION.. How often than should I top off my batteries.. every month every other month ?
                    Fluid level checked monthly, full charge 2x a week
                    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

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