chucks is right. e.g. the D100 battery grip can use AA batteries, but they don't last very long, less than 100 shots in fact. also the S2 Pro uses AA size batteries, but the short battery life is one of the major grouses of S2 users.
S2pro battery system is good, tested in 0 degree, snowing condition just last week, quite long lasting. So afraid the camera might breakdown at that low temperature. But luckily it didn't. Hope fully it didn't had any internal injury and breakdown later.