I've recently had a mover fitted plus a leisure battery and now I want to run the interior lights off the battery how do I connect the battery to the bip. There isn't a booster fitted , I have a separate ctek charger I did think it would be straight forward using no12 connection (15amp fuse) can anyone help

I worked out which terminal the 12v supply from the towing vehicle is connected to. Then it's a simple matter of wiring in a changeover switch so you can switch between leisure battery and towcar battery.