Mercury Topaz Problems?

I have a 1990 Mercury Topaz with about 40,000 miles on it. It runs smoothly and has only needed minor work on it. But recently I've been having trouble with the battery dying while I've been driving. I've had the alternator checked, a new duralast gold battery installed, and have had new belts installed. I live in Ohio so the weather has been pretty cold lately. I'm wondering if it cold be the weather or if there is some underlying problem. Any suggestions or help would be greatly appreciated.