please help .. know im way out of my league talkin to you chaps but trying to convert an old 1964 vw camper to both 230 and 12 v managed to acquire my self a zig unit ( think thats what there called) that will swap between voltages charge an additional battery and distribute 12v .. have no instructions and a knot of cables .. can fathom out the mains but beyond that clueless ... says cramer d-5750 menden model csc-lu1-4 on the unit .. know its prob simple .. any ideas thanks