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post #1 of 3 Old 01-16-2011 Thread Starter
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solar overcharge?

Is there any danger of overcharging with a small,(1/2 sq ft) charger in the winter?
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post #2 of 3 Old 01-16-2011
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it depends on the size of your battery, but with a 5 watt solar panel, even a 25 amp battery should be safe without a regulator. to be sure, just check the voltage of the battery with a multimeter at about 2pm on a sunny day. if it reads under about 14 volts it should be o.k. most batteries will take about 14.2 volts.. i would be surprised that with your solar panel, (which sounds like about 1 to 2 watts) that the voltage will be above 13 volts,even on a 15 amp battery

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post #3 of 3 Old 01-16-2011
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That's about six watts maximum. I do not know what latitude you are, but if you figure six hours of daylight with the solar panel pointed the sun at noon, and then lets say you get half the rated amount as the panel is not always directly pointed at the sun, that comes to less than a watt in 24 hours average. That computes to about 60 milliamps at 13 volts. The internal discharge rate for a hundred amp-hour battery is going to be near 60 milliamps for an older battery, so I would say you could get away with no regulator. It would certainly be better than no panel at all where you would have sulfation of the battery over the winter and loose about half the capacity of the battery. Two winters and you need a new battery.

Last edited by LakeSuperiorGeezer; 01-16-2011 at 04:32 PM.
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