A word of advice.. and I need to do it in my own finder/battery box.. put a piece of SM/styrofoam under the battery to insulate it from the ice. That way, when you're in your heated hut the battery won't lose power by getting chilled sitting on the ice. Other option is to just carry a piece of SM in the tobogan and sit the whole unit on it.
I also have a cord made up for mine so that I can plug it into the finder box, to charge the batteries while moving locations on the sled... using my heated helmut jack.