If its the type of fridge that is built into your motorhome then it does not usually run off the leisure battery alone as this would drain it very quickly. Normally they are gas and 240v. When you are on the move in the van you tend to find there is a switch marked 12v and this is turned on and is only active when the engine is running so the battery can run the fridge and keep the contents at a cool temperature until you park up again and plug in the 240v or ignite the gas.
Just about half an hour i would guess, you are not supposed to use the leisure battery to power your fridgethe battery is supposed to be charged as you drive around ie. engine running, the fridge is run by a relay so it can only run when engine is running, on site you either make use of the electric hook up or turn it to gas. Does that make sense???
Our coolbox stayed on for about eight hours via the leisure battery which is kept under the passenger seat, but this wont use as much energy as a fridge. I agree witht wineciccio, best get it onto the hook up asap.
i found out the hard way at the weekend with a dead battery on the beach in my T25 campervan...
danboyfat is correct gas or 240v hookup and the 12v runs it off the van battery and not the leisure battery.. only use 12v switch when van running or stopped for fuel stop..
Depends on the type of fridge. Ours is a top-opening coolbox style which only runs on the leisure battery or mains hook-up (no gas). We regularly stay in one place for 2-3 days with no hook-up and even in hot weather and using the lights in the evening the battery still has some life in it.