| We recently received an enquiry from someone who was unhappy with the briefcase style solar charger he'd bought so we calculated why it wasn't charging the caravan battery enough by reviewing the solar kits:-
The battery in the Caravan was a 12 Volt, 120 Amp hour lead acid battery. To calculate the number of Watts this battery could store/deliver you multiply the Amps by the Volts
12 Volts X 120 Amps hours = 1440 Watt hours
It's not a good idea to completely drain a battery. More than 70% would be too much so that leaves 70% of 1440 which is approx 1kW hour (Equivalent to a 100 Watt TV on for 10 Hours 10 X 100 = 1000 Watts or 1kW)
If you've had the TV, fridge and lights on enough to drain the battery by 70% we need sufficient solar energy to put 1000 Watt hours (or 1kW hour) of power back in the battery. The fold-able solar panel is rated at 15Watts and was placed out in the sunshine for about 6 Hours:-
15 Watt panel in sunshine for 6 hours is 6 X 15 = 90 Watt hours
To allow for losses and inefficiencies it's normal to reduce the output of all solar panels by a factor of between 0.8 and 0.7 so:-
90 Watt hours X 0.8 factor = 72 Watt hours true production
We need 1000 Watt hours so the briefcase style solar panel will take nearly 14 days to charge it. That's ok if your not using the caravan but definitely not if you'r touring.
1000 Watts required at 72 Watts per day = 1000W / 72W = 13.89 Days
The solar panels we would include in a suitable kit would produce about 480 Watt hours and will therefore recharge the battery in less than 2 days.
- Fold-able panel charges battery in 14 Days
- Our kit charges the battery in under 2 days
We design and supply professional solar kits that won't let you down! If you'd like some more information or help on any of the above please feel free to contact us here.
We are always pleased to help!
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