Hi all,I have a 1990 hymer b544 and am not sure how to switch from 240 to 12v, there is a red key by the drivers door which you can remove and put into a different key hole that turns the inverter on,everything then goes dead,Both batteries are new. many thanks .
All your 12v runs from your leisure battery, some Hymers have another switch to let you also use the vehicle battery as an emergency (not recommended) and as soon as you hook up then your 12v battery is being charged, so you are then sort of running your 12v from the mains and your 240v sockets will then work.
My B534 has a switch so you can turn the battery charger off, but I just leave it turned on, so I don't forget to put it back on.