Pull batteries or keep the shore power plugged in

[sbw1]

There should not be any stray currents drawing down connected batteries if you turn off all of the switches.

 

[JVM225]

I do this, too. Although I am not a fan of plugging in the boat when it’s been a hard freeze for a while. Charging frozen batteries is not good for them.

Oddly enough, I don’t get much freezing under the shrinkwrap.
Probably because of the shrinkwrap blocking the wind and the boat cooking under the plastic when the sun is out,
I usually put a bottled water in the galley sink over the winter and rarely get it to ice up.
My old boat was blocked up on my private property with full exposure to the sun and I rarely saw any ice forming in the bottled water.
Last winter was my first full one with my current boat and because of the size I had to winter in a boatyard.
I did get a bit more freezing during some extended cold snaps, but I attributed it to being blocked up between two other boats that blocked more sunlight.