10 days with new alkaline batteries/ 8 hours with fully charge built-in rechargeable battery. 1 days with new alkaline batteries/5 hours with fully charged built-in rechargeable battery. 2 days with new alkaline batteries/2 hours with fully charged built-in rechargeable battery. Power is not on. Rechargeable Battery Pack is not plugin properly. Re-plug the Rechargeable Battery Pack. Rechargeable Battery Pack in not function. Rechargeable Battery is in sleeping-mode.