External Power Packs?

[Jorgo]

I want to use my 10D in a very cold environment, down to about -20C.

Can anybody suggest an alternate electricity source?
I fear that the BP-511's won't last very long at this temperature.

[scottbergerphoto]

Check out the Digital Camera Battery( http://www.digitalcamerabattery.com/ ) and Quantum's line of batteries( www.qtm.com ).
Scott

[ssim]

I have had my 10D out in weather exceeding -30C for extended periods of time. I really didn't have issues with the BP511's giving up before I had to. I always had two batteries and kept one in my pocket to keep it warm.