Nilay Patel, The Verge:
13 hours and 29 minutes. That’s all you really need to know — that’s how long the new MacBook Air running Safari lasted running The Verge Battery Test, which cycles through a series of websites and images at 65 percent brightness. Run time in Chrome was shorter, at 11 hours and 29 minutes, but both are still ridiculously impressive. In fact, it’s the record for a laptop running our test without an external battery.
It’s the same story for Tim Stevens at Engadget:
This year’s Air survived 12 hours and 51 minutes on a charge. That’s a stunning number from a laptop this thin, achieved with WiFi enabled and without any external batteries.
PC Magazine’s Joel Santo Domingo got an even more impressive result:
The new MacBook Air 13-inch lasted a staggering 15 hours 33 minutes on our battery rundown test. That is more than double the six hours we get from the best ultrabooks using 3rd-generation Intel Core processors…
These results are with Mountain Lion, too; imagine the kind of battery life you can expect with the totally bitchin’ advances in Mavericks.