UPDATE - just checked this I40 again and the battery life is advising 55% with another 300 pic's taken (mostly night pic's). this means it has now been clicking away on a tree for 5 months and the batteries still have 55% life. i did go ahead and replace them this trip. i try not to let the batteries get below 50%, this way the trigger times will not be effected. i bet i could have got an easy 7-8 months out of a set of batteries.