How funny, there was just recently some testing done on another forum with NiMH rechargeables and freezing (or near freezing) temperatures.

Testing of NiMH rechargeables at 36F / 2C

Bottom line is that Powerex 2700's were tested by one member and Sanyo Eneloop 2000's by another member and they still produced 85-90% as much energy output at near-freezing temps as they did at room temperature. NiMH is rated to about -20C (-4F) so to see two different brands still performing so well at just above freezing was actually somewhat surprising.



As for self-discharge rates, self-discharge is rated at 12% in the first 24 hours, then about 12% a month after that. The low discharge cells are better, with the Rayovac's rated at something like 15% in 3 months, and the Sanyos at 15% a year.