I have been using NiMH batteries for years but they don't last as long as a good Alkaline "I get the recommended 22hrs out of Alkaline" but nowhere near with the NiMH so you have to make sure you carry some spares and have a good charging procedure to maintain best results "and yes I still carry spare Alkaline as my NiMH are dying after years of use. 2100mAH and 2300mAH ones."