I;ve had my Stealth cam for 2 yrs now, and use energizers. They always last me a good 35-40days. Iactually never had them go completely dead, just always changed them in that time frame to be safe. But I'm thinking they'd go longer yet. Most the time my roll of 24 exp is taken by then w/ several recorded events beyond the 24. My cam is 85 miles away from my home at camp, so it only gets checked that often in spring & summer.