If you are referring to the switch to isolate the mover, then that is all it does. Inside the caravan, on your control panel, there should be a separate switch to control mains power entering the caravan and hence the battery charger.
The mover switch isolates the mover from the battery. It has nothing to do with the mains input other than being positioned to prevent connection of the mains lead whilst mover is in use.
I fitted a 2 way switch, I can select Mover/Caravan/Both/None.
I leave it in the off(none) position when the caravan is stored, the battery does not discharge due to parasitic losses
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