“Some bit of software within Mountain Lion indeed appears to noticeably reduce battery life for Apple’s portable Macs,” Chris Foresman reports for Ars Technica.
“Following on numerous reports lodged in Apple’s support forums, we did some additional testing using our Retina MacBook Pro review unit, which seemed to lose approximately 38 percent of its previous 8-hour runtime after installing Mountain Lion,” Foresman reports. “Apple support technicians are continuing to gather evidence from users reporting problems, though at least one user has been told that an update from the Mac App Store should address the issue.”
Foresman reports, “Following our coverage, several Ars readers confirmed via comments and tweets that they were experiencing similar problems. But some claimed that their battery life under Mountain Lion is as good as or better than it was under Lion, so the problem does not appear to affect all users.”