Is it already fitted in a caravan?
The 12volt normally only works from the tow car while towing. It does not run from the leisure battery in the caravan. Mains 240volt or gas is used for that.
As above it only works when the car is connected and the engine is running to provide enough charge for the car & caravan battery and ebough spare capacity for teh fridge.
It wont run on 12v from teh leisure battery alone, the battery would be dead very quickly if it did.
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