One of the big factors when laying up a MH esp over the winter is the fact that although everything in the van appears to be 'switched off' many items are still connected and drawing low current. On my van I have the webasto, the main control panel, the
inverter, the
solar controller (yes they have a small current draw when not charging) and the TV aerial amplifier which I always forget to turn off
all drawing a small current, but they all add up and cause a significant load and lead to me plugging in EHU for a couple of hours every week.
If you've definitely not got an alarm, tracker etc fed from the leisure
battery and topping up is a faff I suggest disconnecting a lead from one of the
battery terminals when laying up for a prolonged period of time.
Merl