Power supply

Tastpa the best supply is the most direct, 240 volt conversion from battery will have some extra losses, albeit small these days. Happy Tvanning from fello Tvanner

Battery power need to be converted to AC in order to run your fridge at 240V setup. Whereas, if you connect the fridge through Hella/merrit plug, it would draw 12v directly off the battery. I would keep it direct as any conversion means chances of losing power in between. Quick googling shows that typical inverter lose 20% of power converting from DC to AC.

When you talk about powering your frige from 240 V I take it you mean through an inverter. If you are doing that then you are incurring two lots of losses. The first is in the inverter. The second is in your power supply when you convert from 240 V back down to battery voltage. Go direct from your battery as the others have suggested.

However if you are on mains power then power your fridge from the mains through the power supply. This gives your battery charger a better run whilst it is bringing your battery up to full charge.

Tastpa

I also have a TVAN, although a MK2. The 240volt outlets only work when the TVan is plugged into 240volt through the outer socket on the Right hand side. If as you mentioned you are only using the battery as the power source only the 12volt merit plugs will have elctricity.
Should you then want to use 240volt as mentioned by others you will need to plug an invertor into the merit plug.

Alan

Quote you will need to plug an invertor into the merit plug.Unquote

And any inverter big enough to power a fridge will far exceed the rated current capacity of a Merit plug. So a 50 amp anderson plug may be more appropriate.
Regards Philip A

Thanks everyone for the info!!