New MacBook Air undergoes battery test

By James Galbraith

When Apple revealed the new MacBook Air at WWDC, the highlighted feature was its drastically improved battery life. While Macworld Lab didn’t experience the 12-hour battery life cited by Apple, our tests do show that the new MacBook Air lasts considerably longer than before. And our results were the best we’ve seen from an Apple laptop.

To test battery life, we ran two different tests on the new models, last year’s models, and a 2013 13-inch Retina MacBook Pro. In both tests we set the brightness to maximum and made sure that automatic brightness adjustment was off, backlit keyboards were off, and Screen Saver was set to never start.

Movie test
In the first test we looped a movie clip in full screen mode with Wi-Fi disabled. The new 11-inch MacBook Air lasted 6 hours and 6 minutes, compared to just 3 hours and 34 minutes for the 2012 model. The new 13-inch standard configuration MacBook Air lasted 8 hours and 18 minutes, 36 percent longer than the new 11-inch MacBook Air, and 65 percent longer than last year’s 13-inch MacBook Air. Compared to a 2013 13-inch Retina MacBook Pro, the 13-inch MacBook Air lasted 75 percent longer.

We also ran the tests on “ultimate” configure-to-order (CTO) MacBook Air models from this year and from last year. There wasn’t too much of a battery life hit on the new CTO model compared to the standard configuration; the standard configuration model lasted just 11 minutes longer than the CTO unit that has a faster processor, more RAM, and twice the hard drive capacity. Comparing this year’s CTO “ultimate” to last year’s, we saw that the new model lasted 65 percent longer.

Peacekeeper test
The second set of tests used Futuremark’s free Peacekeeper browser test, which has an option to run the online test repeatedly and report the time at which the system being tested stops responding. This test is much more taxing than the movie playback, using more of the system’s memory and processor. Hence, we found that the laptops couldn’t last as long when running the Peacekeeper test, but did find that the performance still scaled per our expectations.

In the Peacekeeper tests, the new 13-inch standard configuration MacBook Air lasted the longest at 5 hours and 45 minutes, which was 2.5 hours less than in our movie test. The new 13-inch standard configuration model lasted 41 percent longer than the new 11-inch model and 25 percent longer than the new CTO MacBook Air. The new standard configuration 13-inch Air lasted 63 percent longer than last year’s 13-inch MacBook Air and 67 percent longer than the 13-inch Retina MacBook Pro.

The increased battery life is the result of two under-the-hood changes to the MacBook Air. First off, there is more battery capacity. iFixit’s teardown shows the new models using slightly higher capacity batteries. Second, the new MacBook Air has also switched from using Intel’s third generation Ivy Bridge Core processors to fourth generation Haswell processors. A key difference between the generations is decreased power consumption, which results in increased battery life on the portables it powers.

Why don’t our test results match the claims that Apple has for battery life? It all depends on how you come to the numbers. Apple states “wireless web” and “iTunes movie playback” when qualifying its battery life numbers, but the company doesn’t reveal how it performs its test and all of the settings they use–which, in all likelihood, are considerably different from what Macworld Lab uses. Still, the new MacBook Air’s battery life is bigger and much, much better than before.

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