I had a funny experience with Battery life and cold weather.
Me and my Wife went to Northern Finland for a winter Holiday.
This was end of January, and we went out skiing, not the downhill type but the long run type.
Anyway I had my Sony digital camera in a camera bag around my neck.
The Temperature was around -30C (-22F).
I had charged it over night, and only disconnected it just before we went out.
Anyway we come across this beautiful frozen lake, and I get the camera out.
I turn it on, and try to take a picture, but the camera immediately warns of low battery and shuts off automatically.
Well, later we go to the ski gear shop, and I see this one use hand warming things.
Basically it is a small plastic thing with some chemicals in it, once you open it, it gets hot for about 4-6 hours.
I stick 2 of those in the camera bag, one next to the camera and the other next to the spare battery.
An added bonus was that you would not freeze your hands of on the metal casing of the camera every time you wanted to take a picture, it would actually warm you up instead.
And from that day on, we had no issues with the camera, we did have a good laugh at the other tourists struggling with their video recorders and such, And then telling them of our solution.