We run a dual battery system to keep things charged. Its a Pirahana DB180S unit.
We have just fitted an Optima Red Top as the main starting battery as the original battery is now 7 years old.
An AGM battery is used for running most of the accessories.
The AGM battery does not seem to have any trouble running the fridge for a few days. Once we get into the warmer climates it will be interesting to see how it does with the fridge running more often.