If the Control Panel is the same as on our van, ensure the master switch is Off.
The Hab/Van switch is to direct the charger to either the Leisure Battery or the Vehicle Battery for when on Hook-Up. I would leave this switch on Habitation.
Is the Fridge Power Selection Automatic? or do you have Battery and Mains Power Switches. If so, ensure these are in the Off Position.
After the Leisure Battery has been charged on Hook-Up, let it settle for an hour or so and if you can get at the terminals set the Multimeter to DC Voltage and see what the voltage is (it should be at least 12.5V) and note the Battery Level on the Control Panel. After a day or so (or earlier if the CP Meter is showing less than originally noted) try the Multimeter across the Battery Terminals again. there should be very little difference if the van has not been used.
Have you checked to see if the Battery Terminals are Clean and tight on the Posts??? Even if the Nuts are tight, try moving the clamps to ensure they really are on securely.
Is anything else connected directly to your battery such as a Radio or alarm etc.
Best of Luck
