Charge controller recommendation please...

BAleiHi
BAleiHi Registered Users Posts: 1
in Solar Beginners Corner #1
I'm toying around with two donated 130W panels with which I want to charge a lead-acid 18AH battery to run a small water pump that moves some rain catchment water between various bins. I figure I need a charge controller. I don't anticipate using both panels, but I might want to use them both for some other project in the future. I see some really cheap ($15) MPPT controllers on eBay and am wondering if I should just get one of those or if I should go with a better quality PWM controller for this application and get another one later if I need to handle higher voltages. If I go the PWM route, what is a reputable brand and about what should I expect to spend? Of course, my questions may be way off base (newbie alert). So feel free to just give advice! Thanks....
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
    I got one like this one http://www.ebay.ca/itm/12V-10A-PWM-S...item3aad144552 and have it on a single camper battery for 3 years now and a 70 w panel, I use a generator powered car battery charger once a year to top it off and let the PV keep it up in the summer.... buy 2 as you have 2 PV... look for one that ships a manual with it, a lot of the sellers do not mention the manual... enjoy. ps don't waste your money on MPPT ( Probably isn't at that price) and a single panel arrangement. stay with PWM
     
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #3
    An 18 AH battery bank--You really should limit its solar array (PWM controller) to roughly:
    • 18 AH * 14.5 volts charging * 1/0.77 pane+controller derating * 0.13 rate of charge = 44 watt array typical maximum
    • 18 AH * 14.5 volts charging * 1/0.77 pane+controller derating * 0.20 rate of charge = 68 watt array better not to exceed
    If you pump too much current into a battery while charging, you can over heat them or even over voltage them.

    The amount of solar panels you have--You could support a much larger battery bank 13% rate of charge suggested maximum (5% to 13% is typical solar charging current):
    • 2*130 Watt array * 0.77 panel+controller derating * 1/14.5 volts charging * 1/0.13 rate of charge = 106 AH @ 12 volt battery
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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