A new report has pointed to a large number of users on Apple support forums that are complaining about reduced battery life on various MacBook models following the installation of the latest Mac operating system, OS X 10.8 Mountain Lion. As highlighted by Ars Technica, there are a substantial number of MacBook Pro and MacBook Air users who are suggesting that battery life has been decreased by up to half.
From personal experience, it doesn’t seem to be an issue. With a 2011 MacBook Air, battery life after full charge is staying pretty consistent with Lion, with 4.5 hours of estimated usage time left being reported. Whether or not this estimate is actually accurate is perhaps the issue, but the battery doesn’t seem to be draining any faster.
One feature that may be causing a sharp decline in battery life is the re-indexing of the hard drive or SSD by Spotlight following the installation of Mountain Lion. Certainly, the process ‘mdworker’, which is used by Spotlight to create an indexed database of hard drive contents, has been reported in the past to consume a large amount of system resources as it re-indexes one or more drives. However, as pointed out by other users in the forum, once this process has completed and Spotlight has indexed the drive, the system should return to a normal resting state and battery life should once again be as expected.
That said, some users are suggesting that Spotlight is not responsible for the battery drain and that something else may be involved. However, Apple support representatives are reportedly attempting to determine what, if any, problems there are.