How long does it take to charge a 12v deep cycle battery with a 10 watt solar panel?

Question

I want to also know if the 10 watt rating on the solar panel is 10 watts per day or is it constantly adding 10 watts? Is there a time which the 10 watts is being added like 10 watts per second or 10 watts per minute and so on?

Answer 1

120 hours of peak sunshine, I'd say give it a month.

Answer 2

a 10w solar panel means  at peak efficiency ( high noon, panel pointed flat at the sun, hitting it at 90 degrees), 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 forever and a day to charge a deeply discharged deep cycle battery..........

consider that a small 110v battery charger is putting out 3-5 amps ( or 3 x 110 =330 Watts) and the alternator on a car is putting out 20 to 50 amps at 14 volts ( 280 to 730 Watts).

Answer 3

Normal power is measured in kilo watts per hour. It sounds like 10 watts would be very small  to do anything.  

Answer 4

It will put out 10 watts in full sunlight at noon, less at other times of the day.  That means 0.83 amps, so just divide the battery capacity (in amp-hours) by 0.8 and you'll get an approximate charging time under full sun.

Answer 5

Watts is a measure of energy per second. IE joules per second. 10 watts = 10 joules/second

Car battery capacities will be measured in mAH  (milli-Amp hours)

capacities vary greatly although they will still take a fair while to get charged by such a tiny power charger.