Battery Life

The MacBook Air sees no increase in battery capacity over the previous generation, as a result any improvement in battery life boils down to what we get from Ivy Bridge. I'm stuck rebuilding the battery life results database from scratch now that I've built a new suite of tests for OS X. I've run all three generations of 11-inch MacBook Air through the new suite but I don't have numbers for the older 13-inch MBAs unfortunately. As I mentioned in the rMBP review, the new suite is designed to give accurate data points at three usage models: one light, one medium and one heavy. The combination of all three should give you an idea of the behavior of these systems on battery.

Across the board battery life of the 13-inch MacBook Air is actually quite similar to the Retina MacBook Pro, just from a much smaller battery and without the variability introduced by the rMBP's discrete GPU. If anything the lack of a discrete GPU makes using the MacBook Air much simpler from a battery life perspective. As much as I love Cody Krieger's gfxCardStatus application, it's nice not having to keep an eye on it to see if something silly has triggered the dGPU.

Light Workload Battery Life

Under light usage the new 13-inch MacBook Air is easily able to meet Apple's claim of 7 hours of battery life. The 11-inch model does the same to its 5 hours rating, beating it by the same 30 minute margin as the 13.

Medium Workload Battery Life

The medium workload thins the herd a bit, with the 13-inch Air still coming out on top but at 5.35 hours. The 11-inch Air drops below 4 hours, which is an improvement over the previous two generations of 11-inch Airs. Once again we see an example of Ivy Bridge doing better than Sandy Bridge when it comes to mobile power usage.

Heavy Workload Battery Life

Under heavy load is really where we see Intel's 22nm process deliver the gold. Here both of the 2012 MacBook Air models do very well. With the 13-inch MBA significantly outpacing even the rMBP with its 95Wh battery, while doing the exact same amount of work.

The 13-inch MacBook Air continues to be Apple's best notebook for those who care about battery life. The 11 offers portability but you do take a significant hit in battery life.

Power Consumption & Thermals Final Words


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  • TechKnow12 - Saturday, September 22, 2012 - link

    I too was planning on buying an SD card to use as extra storage. I just bought a 128Gb MBA rather than 256Gb as it was $300 cheaper. Firstly, I wasn't aware of the deep sleep issue with the SD card however I discovered the same issue with leaving a USB drive connected. I'll investigate your two solutions below. Thanks for posting that info!
    Lastly, I did some research on SD card performance/speed. Something to keep in mind for anyone who is also planning to do this, the cheaper ones only have a speed of around 30MB/s and the faster, more expensive ones with a speed of 95MB/s. When you compare the cost of the faster cards to the option of buying a MBA with the 256Gb's, the best option would have been to buy the 256Gb MBA.
    The following is a short speed comparison of SD cards vs. USB vs. MBA SSD:
    SD 30MB/s = 240mbps
    SD 45MB/s = 360mbps
    SD 65MB/s = 520mbps
    SD 95MB/s = 760mbps
    USB 2.0 (60MB/s) = 480mbps
    USB 3.0 (625MB/s) = 5000mbps
    MacBook Air 2012 SSD: writes at 364MB/sec, reads at 461MB/sec

    In speed order:
    SD 30MB/s = 240mbps
    SD 45MB/s = 360mbps
    * MacBook Air 2012 SSD: writes at 364MB/sec, reads at 461MB/sec
    USB 2.0 (60MB/s) = 480mbps
    SD 60MB/s = 480mbps
    SD 95MB/s = 760mbps
    USB 3.0 (625MB/s) = 5000mbps

    So for best performance (read/write speeds) I would go with the 60MB/s SD card however it is expensive. Around $300 for 128Gb. Thus it probably would have been better to buy the MBA 256Gb version. Or you could go for a Sandisk 128Gb 45MB/s card for $170. Slightly slower then MBA's SSD but should be good enough for music and video files (I think). Would be good to find out from anyone using an SD card for storage what they think.
  • TechKnow12 - Saturday, September 22, 2012 - link

    Sorry, made an error with the SD 65MB/s in the first list. Should have read:
    SD 60MB/s = 480mbps not SD 65MB/s = 520mbps

  • phillyry - Thursday, March 28, 2013 - link

    Dude. The ssd speeds and sizes are both in MB/s and GB, not Mb/s and Gb. So, the internal storage (SSD) is running at 360-460MB/s and your SD cards are capped out at 95MB/s.
    400MB/s is clearly better than 95MB/s. No need for conversions, as they're both already in MB/s.

    The Sandisk 45 MB/s SD card is an ORDER OF MAGNITUDE SLOWER (10x) than the SSD in the MBA.

    You would only buy an SD for either transferring files or getting a little extra (non-critical) storage capacity.

    Not only will the drive be slower than a typical mechanical hard drive - only the 95MB/s ones will pass a basic 80MB/s HDD - it will be around 1/10 to 1/5 the speed of the SSDs in the 2012 MBA.
  • cookiezulu - Wednesday, August 1, 2012 - link

    In the meantime I have found (via another user - thanks Ken Ng) that there are too apps on Mac App store for this purpose (unmounting external devices when laptop goes to sleep and remounting them automatically when laptop is taken out of sleep):

    - AutoEJECT (by DragonBTV developer)
    - Jetisson (by StClair Software)
  • TechKnow12 - Saturday, September 22, 2012 - link

    Well, I got really fed up with the performance of my WIndows 7 based netbook and the lack of good and abundant support from the netbook manufacturers website. Apple has that many forums that you can always get some sort of assistance somewhere. As for Windows 7 it is less intuitive than Windows XP which for me personally resulted in a less than desirable user experience. My netbook had a multitouch touch pad but not as advanced as MBA.
    I was rather impressed with the performance and quality of the MBA that I decided to take the plunge and get one. Now this is my first ever experience with Mac and OSX. It took me a little bit of acclimatising however OSX is so much easier to use, more intuitive. The experience so far has been awesome. There are lots of hidden tricks with the touch pad which are awesome too.

    There are too many PROs to list. As for CONs there are just a couple which I've encountered. One that is easily fixable is the auto adjusting screen brightness. On a cloudy day where ambient brightness can change constantly as clouds move by, the brightness fluctuates constantly to match. Not very pleasant for the eyes. Simple fix is to turn off this function. The other is web page loading where Safari just hangs and does nothing until you re click on the link or cancel the page load then hit refresh. Doesnt seem to be a problem with Firefox.

    Battery life is good and as stated. Cut a couple of hours off that if you're streaming Youtube clips or playing music. But again, as it goes with battery life, it is all subjective to how you use the MBA.

    So will I ever go back to Windows? No.
    I've been running Windows 8 RC on a spare PC and it is less intuitive than Win 7. It's actually quite horrible. Not something I would want to use permanently.

    I think more people are going to be making the switch to Mac in future.
  • TechKnow12 - Monday, October 1, 2012 - link

    Heh hehhh! I'm going back on my word or rather on my statement above regarding Windows. :p
    Since actually having tried out Bootcamp and installing Windows 7, I can now run Win 7 natively and run Win only programs. Win 7 runs really well on MBA. Battery life is about the same. Voice control works well with the inbuilt microphone.
    I love how Bootcamp has given me dual boot functionality as I originally thought Bootcamp was akin to VMWare.
    It's virtually like having two ultrabooks in one. One Mac and one Windows.
    Unfortunately Safari swipe gestures (back & fwd) aren't supported under Windows.
    And OSX doesn't have voice control to control everything like Win 7 does. But I guess that will come soon as Siri develops and hopefully makes it to OSX. :)
  • ald - Friday, November 16, 2012 - link

    I was wondering about the calibration profile provided for the LG display of Macbook air, to me it seems like it makes greys a little brown and whites a little yellow, and when you look at the display from side it has a weird green tint. Does anyone else have the same problem. I have downloaded this profile from which seems to do a much better job. Reply
  • tdtran1025 - Tuesday, November 27, 2012 - link

    The time is right for Apple to deploy their brew of ARM-based SoC in Airs, basing on the performance of the latest iPad. It would make sense for Apple to indulge this form factor to increase their gross margin, and for those who despise touch typing. I am sure Apple will find ways to increase the performance of the current ARM processors to match that of low end Intel C2D within 18 months. All that power saving may push battery performance to beyond 5 hours in the Airs, something we can all go for. Reply
  • phillyry - Thursday, March 28, 2013 - link

    Are you crazy?

    Arm is nowhere near where it needs to be to run OS X.
  • DPsocial - Wednesday, January 9, 2013 - link

    This computer is absolutely perfect for college My roommate used this computer through college, very light and perfect for going to class. Highly recommended. Reply

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