OS X Battery Life Analysis from Snow Leopard to Mountain Lion

| Analysis

MacBook Pro OS X Battery Life

Update: The final builds of 10.8.2 and 10.7.5 were released by Apple on September 19. We have put those builds through the same test and the results can be found here.

Last month we performed a series of battery life tests on three Mac laptops: a 2011 15-inch MacBook Pro, 2012 15-inch MacBook Pro with Retina Display, and a 2011 13-inch MacBook Air. We were able to demonstrate that the upgrade to OS X 10.8 Mountain Lion caused a significant reduction in battery life and that Mountain Lion’s first update, 10.8.1, only partially restored the lost running time.

In response to our reports, we received many questions and suggestions for further testing, with some readers telling us that they experienced a similar loss in battery life after the upgrade from 10.6 Snow Leopard to 10.7 Lion. Other readers wanted to know if there would be a significant difference in battery life if the tests were run on a solid state system drive (SSD) versus a traditional hard disk system drive (HDD).

In an effort to provide a comprehensive look at battery life, we decided to take one of our test Macs back to Snow Leopard and test each build of OS X from 10.6.8 all the way to the current build of Mountain Lion on both an SSD and an HDD. We hope that our tests will answer some questions about a Mac’s battery life “journey” though the many iterations of OS X over the past few years.

MacBook Pro OS X Battery Life


Our test computer is a 2011 15-inch MacBook Pro at 2.0 GHz with 8 GB of RAM, a Radeon HD 6490M GPU, and two internal drives: an OCZ Vertex 4 64 GB SSD and a Seagate Momentus 750 GB HDD (we used an Other World Computing Data Doubler bracket to replace the MacBook Pro’s optical drive with the Seagate hard drive).

Our test MacBook Pro, which readers should note is a different computer than the one used in our first tests, has been lightly used during its life. Its battery at the start of the tests had 159 cycles and was considered healthy by OS X. The excellent coconutBattery utility showed that the battery’s capacity was still at 95 percent of its theoretical maximum.

Using the MacBook’s original system installation discs (remember the good old days when Apple used to include those?), we erased the internal drives and installed the version of OS X that the system shipped with, 10.6.6, to both drives so that we could individually test battery life on the SSD and HDD. We then updated each installation to 10.6.8, the last version of Snow Leopard released by Apple.

Testing Methodology

For each test, starting with OS X 10.6.8, we allow the battery on the Mac to reach a full charge. We then disable all applications and services except for WiFi, set the screen to 50 percent brightness, turn keyboard illumination off, disable the screen saver, and set the power and display to remain on indefinitely.

To simulate a moderate workflow, we use a custom Automator application, which is the same as in our previous tests. Our automatic workflow consists of the following steps:

  1. Open TextEdit, pause 10 seconds
  2. Open Safari and navigate to a content-heavy website (macobserver.com), pause 20 seconds
  3. Navigate to a second content-heavy website (cnn.com), pause 20 seconds
  4. Open Mail, pause 10 seconds to allow any messages to download
  5. Close all open applications
  6. Log a time stamp to a text file
  7. Repeat

Regarding the Safari Web browser, which is launched as part of the tests, we used the version of Safari that was common to each edition of OS X at its launch. This means that our Snow Leopard tests use Safari 5.0.5, Lion tests use Safari 5.1.7, and Mountain Lion tests use Safari 6.

The one exception is Safari 6 on 10.7.4, with which we performed an additional test (noted with an asterisk on the chart) to determine if different versions of Safari had any impact on battery life.

To determine the battery life achieved with each test, we use the time stamp created by our Automator workflow to calculate total running time.

Each version of OS X is tested at least twice on each storage medium. We then compare the results and, if the difference between the results is less than 5 percent, we average them. If the difference is greater than 5 percent, we run multiple tests until we can determine which result was abnormal and why. We then discard the abnormal result and average the remaining results.

At the suggestion of some readers, we performed a PRAM and SMC reset following the completion of each test and the installation of the next OS X update. Although we designed our Automator workflow so that it would not trigger the MacBook’s discrete GPU, we also installed Cody Krieger’s gfxCardStatus utility and set it to force the use of the integrated GPU only throughout our tests, just to be safe.

Test Results

MacBook Pro OS X Battery Life

As the chart illustrates, there was a definite and noticeable reduction in battery life with the upgrade from Snow Leopard to Lion. In both the SSD and HDD configurations, we measured a roughly 40 minute reduction in running time. This loss in battery life persisted until 10.7.3, which restored running time to 10.6.8 levels.

10.7.4 maintained the battery life that was regained by the 10.7.3 update, and there appears to be no significant difference between using Safari 5.1.7 and Safari 6 in terms of running time.

MacBook Pro OS X Battery Life Snow Leopard Baseline

Just as we saw in our previous tests, the upgrade to 10.8 Mountain Lion decreased battery life significantly, by about 1 hour and 45 minutes, or 30 percent. The upgrade to 10.8.1 restored about 30 minutes of battery life for our MacBook Pro, an improvement for sure, but not nearly enough to regain lost ground.

MacBook Pro OS X Battery Life Running Change

The big change came with 10.8.2, which is still undergoing developer testing. Using what was the latest build when the tests were run, 12C35 (a newer build, 12C43 was released September 5), we saw a tremendous increase in battery life, to the point where running time was a few minutes longer than even that of 10.6.8.

We must reiterate that 10.8.2 is still a work-in-progress and is subject to change before it is released to the public. We do not know what changes Apple has made to Mountain Lion’s code to account for the battery life increase, or if those changes must necessarily be reversed before release, but we hope that Apple will find a way to preserve the battery life improvements in future Mountain Lion updates.

Hard Disk Drive vs. Solid State Drive

Although battery life across the various iterations of OS X follows the same trend between the SSD and HDD, the HDD achieves between 10 and 20 minutes of additional battery life over the SSD.

In addition to their significantly improved performance, SSDs are also marketed as energy-sipping power savers when compared to traditional hard drives. In our case, however, the design of the test and specific drives used made the HDD the winner in battery life.

According to Western Digital, the Scorpio Blue HDD uses 1.4 Watts of power during active reads and writes and 0.59 Watts at idle, while the high performance OCZ Vertex SSD uses 2.5 Watts while active and 1.3 Watts at idle.

HDD vs SSD Power Consumption

This slight difference in power draw, combined with a workload that is primarily idle, accounts for the 10 to 20 minute battery life advantage we saw with the HDD. So if you need the absolute best battery life for light workloads, a low speed, energy efficient traditional hard drive may be the way to go. Considering the large performance and reliability advantage that a solid state drive has over a traditional hard drive, however, the majority of consumers would be better suited with the SSD, even at the expense of a few minutes of running time.


It is clear that Apple has released the last two versions of OS X with serious underlying code issues that noticeably reduce battery life. The good news, however, is that the Cupertino engineers have worked to remedy the issues within the first two or three point updates to each OS.

Customers still on Snow Leopard who have hesitated upgrading to Lion due to battery life issues should feel comfortable upgrading, as 10.7.4 performs nearly as well as 10.6.8 in terms of running time.

However, customers who depend on their battery life — with all other considerations being equal — should wait to upgrade to Mountain Lion until the public release of 10.8.2. As we mentioned above, although the developer builds of 10.8.2 are very promising, nothing can be guaranteed until the final version of the software has been approved.

We will continue to monitor the development of OS X Mountain Lion and test new updates to the OS as they are released. Until then, we look forward to the final build of 10.8.2 and the promise of complete battery life restoration.

Teaser graphic via Shutterstock.

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Thank you.
This is a very comprehensive series of tests that answers a lot of my questions.


Can you link the script? I can’t seem to save the time stamp correctly.



Awesome article! Really helpful.

Congratulations for the tests. Really professional look.

I’m using 2009 mid Macbook Pro 13” with also battery draining problems. Mountain Lion 10.8.1. give 2 to 3 hours of battery life.

Jon Brown

Thank you!  This is a really amazing test.  I can’t imagine waiting all those hours of rundown time to complete all of it…  yikes…

I’m just curious however if you thought to compare performance across 10.8, 10.8.1 and 10.8.2 using some sort of benchmark test?  I wonder since a lot of battery life could be regained by using the discrete graphics less, but obviously that’s likely to affect performance. so just curious…


Wow, great set of stats guys. I shall definatly hold-off upgrading my MBA from 10.6.8 until 10.8.2 is out smile


I think it’s very misguided to suggest here that HDDs are better than SSDs for power consumption. I was puzzled by your results, until I looked into the drive you used and saw that it is one of the more power-hungry SSDs on the market. The results here http://www.tomshardware.com/reviews/ssd-330-review-benchmark,3190-8.html show a much lower usage at idle (which it seems is considered most significant for an SSD, as they read so fast as to be idle most of the time) for many of the SSDs on the market, such as around .4 W for the Samsungs (one of which I just installed in my MBP) — much less than the .59 W for the HDD you’ve tested here. They also show tested figures of about half what you’ve concluded for the OCZ Vertex drive, which leads me to question the differences in methodology.

Ilhan Kudeki

Would you please test 10.6.6 as well?  I and others on the Apple Support Discussion Forums noticed a significant drop in battery life even when updating from 10.6.6 to 10.6.8—the same drop felt when upgrading to Lion.

Please see thread titled “Horrible MacBook Pro Battery Life on Lion” for details and people’s experiences.  Search through pages for the keyword “10.6.6” to do this efficiently.  Thank you.

Dennis Schafroth

Did you count how many times that the above was done? Was there any differences between SSD vs HD? If SSD is a lot faster it will actually loop more times. I know most is wait, but still.

Francis Carden

WHen I brought my brand new 2011 MacBook Pro I was extremely disappointed with the battery life. It was a new 15” model (with SSD) who’s battery lasted about 30% less than my 2008 17” model…. I worked with Apple tech team (through the office of the CEO) to address (August thru December). Certain things would “bolster” Battery life dramatically but after a week or two, it went back to bad. Apple never really figured out why except they did say, the GPU was more inefficient in the new MACs when an older application was using it!

Anyway, we are over a year since I brought it and I am so looking forward to 10.8.2 (I’m traveling else I’d seed it). I’m confident (and hopeful) your results above are not one of the flukes many of have seen that doesn’t last. If it’s truly “fixed” than why doesn’t Apple tell us what it was. Fingers crossed they will.


Now can they make it work with the Apple display.  When images are mirrored, Airbook cannot fill the big screen.  Works fine on my 1983 Albook.

Lorenzo Rainiero

Well, are there any news about?

10.7.5 e 10.8.2 are out…

Bryn Davies

I’d be very interested to see what results you get from the 10.8.2 final release version as opposed to the earlier dev build, as I can see no difference from 10.8.1. The most I have been able to squeeze out of my 2012 MBP Retina is 5hrs since the ‘upgrade’. Very disappointing as that was the ONE thing that I upgraded for.


Did you test the build they finally released because my mac air is still as crap as it was from when I moved to 10.8.1

João Antunes

I have upgraded to 10.8.2, but the battery issues remain


I really compliment to you on the deep analysis! Great! =)

João Antunes

Yes, Kudos for the very well done analysis. My laptop’s battery life stays the same though with the official 10..8.2. Being that my mac is a mid 2010 13 inch MBP. Is it possible for you to update the test with the 10.8.2? I’m curious to know if it’s only my case or not.

Jim Tanous

Greetings! I’m glad our battery tests have been helpful for you. There is a link at the very top of this article (see “Update”) that takes you to our testing for the final builds of 10.7.5 and 10.8.2.


Good article - I wish there were more comprehensive battery benchmark articles around for osx updates like this one..

My Late 2010 Macbook Air seemed to lose about an hour runtime going from 10.6.8 to 10.8.2…  Others have been reporting similar outcomes in the Apple discussion forums.

I have to wonder about something in the testing methodology here:
“...We then disable all applications and services except for WiFi, set ...”

How helpful is that? Why not just leave it as the stock, default configuration when testing.. After all if something obscure like bluetooth radio or other services were causing significant battery drain, your test would miss this.. Almost makes this comparison invalid in my books…

Suggestion: Run your test with an “out of the box” default configuration as this is what most Mac portable user do… Otherwise these tests are misleading and unproductive.

My 2c



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