Just last month Ars Technica published test results confirming what some of us were experiencing- the upgrade to OS X Mountain Lion has been detrimental to notebook battery life. The Mac Observer quickly followed up with they’re own results, backing up Ars’ findings. It seems that OS X 10.8 was responsible for a 33-38% drop in battery life as compared to the levels experienced under OS X Lion. Mac Observer then noted that the recently released 10.8.1 update improved notebook battery life somewhat.
The Mac Observer has done even more testing, this time on the pre-release build (Build 12C35) of 10.8.2, and has found that battery life has been restored to OS X Lion levels with this version of the OS. This update gives users around 380 minutes of battery life, as compared to the 280-300 minutes seen under 10.8.1 and the 260-275 minutes seen under 10.8. Here is a chart of Mac Observer’s findings:
The report wraps up by noting that a similar issue was present to a lesser extent when users upgraded to OS X Lion from Snow Leopard. The battery life issue under Lion was finally resolved with the release of 10.7.3 a full six months after Lion was released to the public. Additionally, it seems that not everyone with a MacBook was experiencing this problem under Mountain Lion, which further confuses the issue of determining what was the precise cause of this problem.
At any rate, it seems that 10.8.2 will completely solve the problem.
Chart courtesy of The Mac Observer.