I have a bog standard 12V/240 setup in my Devon Monaco campervan with the one exception, I have added a second 110 Ah battery. At present the two leisure batteries (and the engine battery if necessary) can be charged from the charger power supply fitted by Devon. I understand that due to the limitations of the 12V system the batteries will not receive the full voltage necessary to fully charge them. I would like to add a multistage battery charger to the system. My questions are these. 1. Am I right in thinking that I just cannot replace the built in charger by the new one due to (a) the higher voltage of the latter and (b) the heavy demand the 12V system may place on the charger? 2. Can anyone offer me a schematic diagram the the wiring diagram need so that I can have both in place but only use one at a time? 3. Am I unduly complicating the situation? 4. Are there any good links you cab direct me to?