Solar Charging – our dependence on cold wine

Camping off grid

Nothing is more catestrophic than warm wine because the battery went flat and we can’t use the fridge. Most modern women only function properly when fed the correct amount of this beverage. Not to mention the steaks and our dependence on ice. It must have been tough on early explorers not to have had ice but I suppose if you never have known something you won’t miss it. There are books written on the subject of how much solar power is needed and how much battery capacity required. We have 2 fridges – a small Engel of 18l on the back seat of the car and a National Luna Twin 50l in the camper. We also have 3 x 100ah batteries – two in the car and one in the camper. When the car is switched off the main car battery is isolated from the “house” batteries automatically. This prevents the main battery from loosing charge due to accessories drawing power so car should always start. (Starting the day with a flat battery is always a good test of the marriage especially when someone has to push). While driving all three batteries are charged but the problem comes if the two house batteries are allowed to get too flat (48 hours in camp with no driving) as charging time of say 8 hours driving will not be enough to get them full. Solar assistance is essential to keep batteries full when the engine is not topping batteries up. Our Klipspringer camper system uses a HCdP electronics MK5 power panel which manages the vehicle and solar inputs in conjunction with its own 100ah high cycle battery and we have the choice of 100 or 180 watts of solar array. 100 Watts is usually more than adequate as our fridge draws 5 amps and the 100 watt panel produces around 5 amps. At first this does not make sense as you are only producing 5 amps and using the same so nothing is going into the battery never mind the 12 hours or so of night when there is no solar production. The answer is that the fridge works on a duty cycle and only draws 5 amps when on and it is more off than on especially when left closed or at night when cooler. To monitor the battery status our power panel tells us the current draw from the solar panel being used by the battery. We can see when the battery is full when the current being drawn by the battery is less than the capacity provided by the solar panel. We can also see when more solar power is needed ie. the battery is taking to long to require less than the panel can supply and at this point we can add an additional panel in parallel. All this for ice, cold wine and a well hydrated wife.