Is OS X Mountain Lion Crippling Laptop Battery Life?
Shortly after OS X Mountain Lion was released, a number of users began posting on Apple Support Communities that their laptops had started experiencing inexplicable battery life issues. Specifically, battery life is being drained exponentially faster with Mountain Lion.
Given the millions of new Lion tamers out there (my pet name for the bazillion people that nabbed Mountain Lion immediately upon its release), the criticisms are loud and growing louder with each passing day.
Most of those reporting the issue say that battery life has dropped by one or two hours. Other cases are more severe, with claims of laptops dying after just two hours of operation with OS X Mountain Lion installed. Making matters worse, hotter machines have even been reported.
Apple is now aware of the issue and is believed to be investigating the matter in hopes of quickly locating and resolving the offending culprit.
Source: Apple Support Communities