Tests Find OS X Mountain Lion May Significantly Degrade Notebook Battery Life


macrumors bot
Original poster
Apr 12, 2001

Ars Technica has been doing some testing after reports emerged that some Mountain Lion early adopters were experiencing degraded battery life after upgrading to OS X 10.8. A 46-page thread with nearly 700 replies has been growing over the past several weeks on the Apple Support Forums.

Ars writer Chris Foresman, after extended testing, discovered that the battery life of his Retina MacBook Pro review unit dropped 38% from its previous 8-hours. He was unable to narrow down blame for the battery loss to any particular bit of software or system process.
Our own testing revealed similar (and significant) drops in battery runtime after installing Mountain Lion. In previous tests, we were able to regularly achieve just over 8 hours of use by relying solely on our Retina MacBook Pro's integrated Intel HD4000 GPU. Performing the same "real-world" test using the same software applications and usage pattern, we never got the Retina MacBook Pro to run for more than a few minutes past 5 hours after a full charge.


Typically, the quad-core processor wasn't taxed beyond 5 percent capacity, except for occasional 10-20 percent spikes when loading webpages, reading or writing files, or other activities. Unexpected file system or network access, or less efficient use of the GPU, could cause additional power drain without showing significant CPU use.
One poster on Apple's support forums claims a company support representative told him that "an update will be issued via the [Mac App Store] as soon as they can work a fix".

Article Link: Tests Find OS X Mountain Lion May Significantly Degrade Notebook Battery Life


macrumors regular
Mar 8, 2012
I personally haven't noticed anything on my MacBook Air, but I'm sure it will be fixed with an update. This tends to happen with new releases. No reason to get worked up.


macrumors 65816
Apr 24, 2009
Ironically, I've used my 2010 MBA in clamshell mode 100% of the time since the upgrade -- So I haven't noticed anything :eek:

Maybe clean install vs upgrade is the culprit? Some old system process conflicting with a new one?


macrumors 65816
Feb 18, 2008
Didnt this happen with Lion too? Apple stated they "corrected" the battery timing mechanism to better report actual usage? And then continued to sell laptops with 8+hr battery life on the store?

I have never gotten anything close to any estimate they have used for sales, even with light browsing/usage.


macrumors regular
Jul 27, 2010
This has happened before with Apple devices and Apple has always responded with a firmware/software update that resolves the issue.


macrumors 6502
Jul 9, 2008
scary, especially because the high price people had to fork out for one of those gems


macrumors 6502
Jun 22, 2010
Mountain Lion has better battery life than Lion for me on a macbook. Lion was brutal for battery life yet there was no real mention of it on news sites.
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macrumors 6502
Dec 22, 2008
Tampa, FL
Oh No! I wonder if this will affect my MacBook Pro now that updated to Mountain Lion. I'm nowhere near a charger right now and running on battery so I really hope that


macrumors 65816
Mar 26, 2008
I hope it's just a reporting error from the battery to the OS, not actual degradation, otherwise all the software updates in the world won't do ****.


macrumors 6502a
Jul 30, 2008
I haven't really noticed anything with my MacBook Pro. It'll be interesting to see what's causing the reduction - to go from 8 hours to a little more than 5 is quite dramatic.

Small White Car

macrumors G4
Aug 29, 2006
Washington DC
We desktop users may be a vanishing breed, but every now and then there's at least some little thing that makes me feel good about it.

For what it's worth, I've never been impresse with Apple laptop battery life. I've always gotten a fraction of their claimed times going all the way back to the G4 days.