In our case the van is stored at home where we have shore power. Still, I make sure the battery is fully charged and then shut everything down. I think if the battery needed charging and was too cold to accept it, when I plugged in the 120 heaters in the battery would kick in and when the batteries got warm enough, could take a few days, the charging would commence. Alternatively, with the batteries needing charging and being cold, I could drive with my second alternator providing sufficient current to run the heaters via the inverter and somewhere down the road, likely way down, the charging could commence.
My basic plan is to store it with full batteries in cold weather, plug in a couple days before departing, and head for some place warm. As my girlfriend says, warm is always better.