Agree with the previous poster. 12F is pretty cold but I'm sure I've done it back in NYC. Without any batteries. On a motorcycle or snowmobile 12v gloves are fine. On a bicycle, not so much. A co-worker gave me some half-dead chemical hand-warmers for my ride home one evening. I was impressed but I don't have the same commute anymore. As I understand it, hand warmers can be made using rice. You charge them in a microwave oven and they stay warm for some time. I'd look into good gloves and some kind of non-electric hand warming option. FWIW.