OK, I have done some more thinking (ouch) I took the junction box apart under the trailer and looked again at the fuse box/transformer thing inside the trailer. Cast into the plastic on the 12v ports on the fusebox it says 'Eingang 12v' and 'Ausgang 12v'. I think that means input 12v & output 12v. I put an oscillator (A bit of kit I use at work to sent a beep down a pr of wires which can be heard and 'homed' in upon with an associated probe) on the eingang or input pr and it traces to an unused pr in the main car to van connection cable. I presume this would be used to feed 12v to the van directly from the car battery if you utilised the second plug setup I have seen on the back of tow cars.
So if my thinking is correct, bear with me here as I know this is boring the hell out of you all, all I need to do is connect a 12v leisure battery to this pr and hey presto we have power where before there was none.
Is there anyone out there who thinks I have it right or will I have to buy a £200 power controller thing.
Bear in mind that I do not want to power the van from the car just a big leisure battery under the van for a weekend at a race track increasing my carbon footprint
