Quote:
Originally Posted by GregAndrew
If I remember correctly, when the voltage is held constant, then amps = watts/volts. So a 5 watt solar charger is only going to give you 5/12 amps per hour of charge. So 12 hours charging time will produce 5 amps. Might need something in the 12 -15 watt range to keep that size battery charged (with the spare battery charging all day).
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You remember correctly. And that 5W rating is
generous. You'll probably only get about 0.3 amps out of it on a sunny day.
You can do the jumper cable thing, but have the vehicle running. And again, monitor that battery, watch for heat or gassing.