240v Frig from 400w inverter

It's difficult to say unless you try it. Then numbers are close and it would depend on the outside temperature.

As a guide, an old small fridge ( 200 l) would struggle at any temp over about 20 degrees. A new small fridge would be ok up till about 30 degrees. Keep in mind that the alternator has to be able to supply about 60A just for the fridge.

When the car isn't running the whole argument is academic as it will warm up

Either way it won't be practical.



A 400 l fridge has no hope.

Are you talking about a bar style fridge or running the 240 V side of a 3 way fridge. If it is the latter, are you wanting to do that because your 12 V operation is not working properly?

I do not know traveling with 240 volts is illegal in a car or caravan but the emergency services take a dim view of having 240 volts around in an crash.

Yes it will work, the 400w inverter will start a normal sized fridge compressor and depending on the compressor current draw it will drag about 15 to 20 amps while running from the 12 source.
Not sure about the legalities.
Best to have the inv in the tow vehicle and feed the 240v to the van for best performance and use of current flows.

Ross M