We live in Ohio and winters are very unpredictable. The first winter I left the batteries in and turned on the heating pad, moved Oliver to the horse barn, non hearted but doesn't get real cold. After the first year I just started unhooking them and bringing them inside. It is not that hard to remove and re-install them. I color coded all the connections, took pics, all the overkill you can do to make sure I put them back correctly. Now if it gets real cold for some period of time I am not worrying about power going out and the battery heating pad not working. House has generator, also way better insulation than barn.
I did call Lithonics a few times and they were always very responsive and helpful.
Just the way I am doing it now.