Fairly new to caravanning and have never used the battery for lighting, only for fridge when travelling. We have a 2005 Compass 636. On a recent trip south we stopped at Killington Lakes for the night but couldn't get the lights to work. Apart from the fuse box under the locker there only appears to be a 12v switch (tried switch on and off)Van is regularly serviced. Does van have to be un hitched from car ? Help and any advice would be appreciated.