Welcome to the madhouse!!
There are many many types of Zig units so a little more information would be required to help you. Most regular members put the details of their vehicle in their signature so that everyone knows which vehicle and what type of camper conversion they are trying to help with.
Some Zig units merely act as a distribution board for the 12v leisure battery electrics, others include a mains charger that automatically charges the leisure battery when the camper is connected to the 240V mains hook up available at campsites. My Zig allows me to switch between using the leisure battery or starter battery as the power source for my 12v electrics.
Pictures paint a thousand words so photos are always a good idea too to help solve questions.
Good luck
Nev
