how does the camper know it's on 240v?

I had a 12 /240v fridge in a Coaster bus. When the bus was running a relay kicked in and supplied power to the fridge 12v. When on 240v (caravan park etc) the bus wasn't running so no 12v, I'm not sure what would happen if bus running and plugged into 240 v. I know what would happen if bus moved whilst still plugged into 240v. (after 20m it wouldn't be a problem).

I would imagine some simply relays would contro the power inputs to the fridge.

RTA

Russell

Apart from Russell's comments on the fridge you generally have 2 separate circuits
complete with switches and GPO's on 240 with dual light bulbs etc.Rosco

most probably a voltage sensing relay and a contactor.

ZJ, mate it would totally depend on how you camper is setup, so noone can really help you with that one. It could be as simple as all your lighting etc is 12V and the GPOs in the van (if there are any) only work when you plug into 240v. The battery paowers everything else and there is a continuous cycle charger that fills the battery when you have 240v power. Others have a transformer that converts the 240 to 12 when you plug in and they will also have a battery charger if they are not relying souly on the vehicle to rechage the van 12v. I have wired up my camper trailer and I used the charger that is plugged into 240v so that when I hook into mains, the battery automatically charges!!

I believe that friges and the like can have both 12 and 240 volt supplied and it will use whatever it has access to at the time, ie 12 when ur off mains and mains when it is available!

Hope that helped!

MAtt.