Appliance Repair Questions? Ask a Technician for Answers ASAP
This is a rather small current, but clearly not good when leaving the van in storage for months on end.
As this is low current, its not the fridge, however there will be current powering the on board PCB which checks for inputs from sensors eg taps, toilet (if fitted with electronic flush), monitors the battery performance and charging circuit which will cycle the battery and decide when to charge it when towing and when to charge it from mains power (if hooked up). When the battery reaches around 25% the PCB should power off so not to fully deplete the battery.
In addition depending on what accessories are fitted it could also be powering the radio\clock as they are often wired on permanent live so not to lose memory \ time.