Walt Mossberg, for AllThingsD:
For these tests, I used the same tough laptop battery test I’ve used for years. I disable all power-saving features, crank the screen brightness to 100 percent, leave on the Wi-Fi to collect email in the background and play an endless loop of music until the computer loses power and shuts off.
For the new 13-inch MacBook Air, Apple claims battery life of up to 12 hours. In my tests, the Air lasted an amazing 10 hours and 14 minutes, the longest any single-battery laptop I’ve reviewed has ever gone and about what an iPad gets.