Back in September, we performed extensive tests to determine the effect that OS X 10.8 Mountain Lion had on Mac battery life. Our tests confirmed the complaints of many Mountain Lion users that their MacBooks were running for a noticeably shorter time while on the go after upgrading to Apple’s latest operating system.
Thankfully, we found that battery life improved to “normal” levels after the introduction of 10.8.2. Unwilling to trust Cupertino, however, we promised to keep an eye on future versions of OS X so that users could know in advance of an upgrade what, if any, change in battery life they might expect.
Now, after three months of betas, Apple released the final build of OS X 10.8.3 Thursday. As the public build is the same as the final beta released Tuesday, we already have some numbers to report.
Measuring the performance of the same Mac from our original tests, 10.8.3 does not noticeably alter battery life, which is good news for those users wary after the problems introduced in the first two versions of Mountain Lion. We measured 383 minutes of running time (6 hours 23 minutes) on our 2011 15-inch MacBook Pro at 2.0 GHz.
We decided to also run tests on our 2012 15-inch MacBook Pro with Retina Display (rMBP). We privately tested each beta build of 10.8.3 on both MacBooks as they were released and, starting with build 12D76, we saw a noticeable jump in battery life on the rMBP. Running time went from 398 minutes, which was roughly the same as the public release of 10.8.2, to 421 minutes, a change that persisted with the final build. These are averaged results that we ran three times to confirm.
We tested other MacBooks, including the aforementioned 2011 MacBook Pro and a 2011 13-inch MacBook Air, and neither machine received a similar boost in battery life. We therefore believe that unidentified improvements specific to the rMBP in 10.8.3 are responsible. Readers should note that these tests were conducted before the release of rMBP SMC Update v1.1. We have installed that update and are conducting tests now to see if it alters our results.
While the extra 23 minutes of battery life is not a huge improvement, it is a nice bonus for rMBP owners and notably gives the product the advertised “7 hours” of productive use for the first time in our testing. A full explanation of our testing methodology can be found in our original article.