Need a small solar system to charge atv batterys

panteramatt
panteramatt Registered Users Posts: 1
in Solar Beginners Corner #1
I have 2 atvs and a lawnmower in my shed and need a way to keep the batteries charged. I also wouldnt mind running a led light inside and maybe a led motion detector. I have a 15watt panel and was looking at a charge controller to hook them up to. Was thinking of hooking up a Schumacher SPC-7A for $18 to it and running a splitter to the 3 batteries. It also has a load out I could run the led lights to. Will this work with the small panel? Should I invest in a bigger kit like this one?

http://www.amazon.com/gp/product/B00DCEKKQ0/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A05654602L3XUQ70M87BV [fix link. -BB]

Read more: http://www.doityourself.com/forum/greening-your-homes-electrical-power-water-systems/540028-need-small-solar-system-charge-atv-batterys.html#ixzz3Lc9SsboQ
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #2
    Re: Need a small solar system to charge atv batterys

    Solar all begins with the loads... To float smaller batteries, you probably only need 5-10 Watts per battery. And you should use a charge controller if you go over ~1% rate of charge (i.e., 50 AH battery, if you have more than 0.5 amps of charging current).

    The kit you are pointing at is probably fine. A 100 Watt panel would keep the following 12 volt battery bank "happy":
    • 100 Watts * 1/14.5 volts charging * 0.77 panel+controller derating * 1/0.01 rate of charge = 531 AH @ 12 volt "floating"
    • 100 Watts * 1/14.5 volts charging * 0.77 panel+controller derating * 1/0.05 rate of charge = 106 AH @ 12 volts maximum battery bank if cycling/weekend/seasonal usage
    • 100 Watts * 1/14.5 volts charging * 0.77 panel+controller derating * 1/0.10 rate of charge = 53 AM nominal if cycling daily
    • 100 Watts * 1/14.5 volts charging * 0.77 panel+controller derating * 1/0.13 rate of charge = 41 AH minimum battery bank for heavy cycling
    If you parallel connect the batteries, remember that a shorted cell/dead battery could "kill" the rest of the batteries.

    If you isolate with a Schottky Diode (low voltage drop of ~0.2 volts), a shorted battery/cell won't kill the other batteries (they may not charge, but won't be killed).

    Anyway, that is a start at looking at the questions.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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