Replacement Battery Pack for Canon LP-E4 for EOS 1D Mark III 10.1MP Digital SLR Camera With constant shooting, flash usage, image review and playback, especially when you have access to additional memory, your standard battery alone will not usually be sufficient. Providing an extra 2500mAh of power, a spare LP-E4 will not put constraints on how you want to shoot. A battery loses power in cold weather, and can become too cold to operate the camera. Keeping a spare battery warm in your pocket to maximize battery power and periodically switching the cold battery for the warm one can significantly enhance battery performance. Memory Free! This LP-E4 can be charged at any time without harm, even if it already has a partial charge and can be typically charged over 1000 times.