So when a solar panel says it's 10watts, does that mean that it is taking in 10 watts per day? How would I determine how long it would take a battery to charge with a 10W solar panel?
a 10w solar panel means at peak efficiency (direct sunlight to the solar panel), you will get 10 watts (at any given second).
Watts = volts x amps
a 12volt battery needs an "incoming" current of at least 13 volts to charge it; 13.5 volts is better, so if the output voltage of the panel is less than 13 volts it wont do anything.
Even if it is, 10 / 13.5 = .74 amp.( three quarters). It will take a long time to charge a deeply discharged deep cycle battery.
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