Hey Alan,

I'm up here in Wisconsin and have to deal with cold weather flying also. In general, batteries will lose power and life faster when they're cold, but a typical 10 or 15 minute flight may not be long enough to get the batteries cold enough to make a diff. It's the spares you have to worry about. I keep my spares in an inside jacket pocket.

My biggest problem is the pilot (me) getting cold - not the batteries.