I am currently renovating a classic Mustang caravan and as part of the renovation i am renewing and updating alot of the wiring.
I am installing a Zig control unit that will allow me to select between car or caravan battery and also switch on/off the pump, lights & aux. This is all working fine but i cannot get the feed to go through my habitation relay to power the fridge. I have a 12v feed from my battery up to the car/caravan switch this then goes down to my relay, wire 6 (red) from my car wiring also goes into this relay so dependent on the voltage the relay it detects it switches automatically. Currently i can only use the caravan battery and this is fully charged (13v) but it does not switch over to power my fridge. Can anyone suggest why not?
Thanks in advance for any advice
A caravan 3way fridge can only run on 12v while being towed by car with engine running, it cannot be run from caravan leisure battery while on site, if thats what you mean. The high current draw at 12v means it can only be run from car battery while towing.
A caravan fridge is 3way, ie it can run on gas or mains ehu on site & 12v while towing. If fridge is very old, ie 1970s I do recall there were 2way fridges then so then yes you would have to run it on gas on site if it has no 240v element. It might be an idea to fit a more modern fridge.
As stated normally the fridge is only supplied with 12v from the car when the engine is running, this is because the fridge will draw a lot of power on 12v and would quickly run the caravan battery flat.
You could bodge it to make the caravan battery supply the fridge but I wouldn't recommend it.
If you wanted to run the fridge off the caravan battery, you would need to change it for a compressor fridge, but then you couldn't run it on gas. Compressor fridges use much less battery power than absorption fridges popularly used in caravans. The one I had on my boat once ran for a week, because I accidentally left it switched on, and there was still plenty of power left in the battery because if there hadn't been the fridge would have switched off. It had a battery-voltage sensing device.