Equalization/Battery Charger

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Joe J
Joe J Solar Expert Posts: 49 ✭✭
in Off Grid Solar & Battery Systems #1
I have a 12 volt system with a Midnite Lite 150. I have 6 solar panels in two strings which equals about 900 watts with about 16 amps of array current. Total battery charging current is about 60 amps which is a little overkill for my 4- 6 volt batteries wired for 12 volts. My question is when it's cloudy for more than a few days and I want to equalize my batteries, what would be the best way to do it. I have a auto battery charger. Can I hook the charger to the Midnite PV + input and ground to equalize my batteries if need be? My charger has a switchable output from a trickle up to about 40 amps. Of course I would shut the main breaker to the solar panels on the roof not to back feed them. Would the Classic 150 regulate the battery charger just the way it regulates the solar panel on the roof? I want to do a manual equalization without over charging the batteries or damaging the Classic. If this is not an option how does everybody equalize on a less than desirable day:confused:
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #2
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    Re: Equalization/Battery Charger

    I would just wait and equalize later, If you need to charge to keep from drawng the batteries down too far that is a different issue.

    Most battery chargers are not designed to charge deep cycle batteries, if you need to charge from the grid I'd look into something like this Iota.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
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    Re: Equalization/Battery Charger

    What you can do is hook the autobattery charger to the batteries and use it to Bulk charge them first thing in the morning, then see if the PV has enough power to finish Absorb and do an equalization charge.

    Do not connect a battery charger to a solar charge controller's input terminals. They are not designed for it.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
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    Re: Equalization/Battery Charger

    More or less, car battery chargers are not very well regulated... And many times, you can crank up the current and really "cook the batteries" with lots of voltage and current.

    You can try a couple different battery chargers (borrow a couple from friends and family if needed) and see if you can get a fully charged battery up to ~15 volts and ~2.5 to 5% of the Battery's AH rating (i.e., 100AH- around 2.5 to 5 amps charging current). If you can--then it will work fine for equalization (of course, only do this when you are checking the bank temperature and specific gravity every 30-60 minutes--and once the SG stops rising between readings, turn the charger off).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Joe J
    Joe J Solar Expert Posts: 49 ✭✭
    #5
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    Re: Equalization/Battery Charger
    Photowhit wrote: »
    Most battery chargers are not designed to charge deep cycle batteries, if you need to charge from the grid I'd look into something like this Iota.


    Thanks guys for the input. I actually own a 55 amp version of that charger. I have it hooked up to my ham radio equipment. Now all I need is to get this...http://www.solar-electric.com/smarcharconi.html and I should be in business.
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