Nice Buck - Cold Batteries

Caught a nice buck over the weekend, 9 or 10 point.  I've been having trouble with cold batteries in my second camera and have not got very many videos from it.  Found out that once they get too cold they can't provide enough energy and the camera turns off and it will not turn on by itself, even if it warms up.  I'm just going to have to buy another 12 volt external battery to get it going in this cold weather.