Two MS-76,SR-44, 357, or similar, or one CR1/3N (or other equivalents to two stacked MS-76 batteries.
Originally Posted by keithwms
I've been out in -13F with an R3 for 4-5 hours with no shelter ( a sunny day on the frozen lakes in Minneapolis), shooting with the camera outside the bag the whole time with no problems, and that camera has much greater demand than the MP on the same battery setup. Battery failure at -3C seems a bit odd to me.
It's not great fumbling with small batteries in cold weather, but you could get a few and swap them into a warm pocket if you need to. I'd suggest the single piece batteries for that. What type of battery was it? Lithium, silver oxide, alkaline ... ?