Battery run times
We tested battery life twice: once running TR Browserbench 1.0, a web browsing simulator of our own design, and again looping a 720p Game of Thrones episode in Windows Media Player. (In case you're curious, TR Browserbench is a static version of TR's old home page rigged to refresh every 45 seconds. It cycles through various permutations of text content, images, and Flash ads, with some cache-busting code to keep things realistic.)
Before testing, we conditioned the batteries by fully discharging and then recharging each system twice in a row. We also used our colorimeter to equalize the display luminosity at around 100 cd/m².
The A4-5000 whitebook achieves much longer run times than the Core i3-based VivoBook. It even edges out the larger, Core i5-driven Zenbook in our video playback test. The Zenbook stays awake an hour longer in the web-browsing run, though.
These are tricky comparisons to make, though, because the systems don't all have the same battery capacities and displays. We can't compensate for the display differences, but we can normalize the data based on the capacity of each battery. The following results show normalized run times in minutes per watt-hour. (For the record, the UX31A has a 13" 1080p screen, while the X202E and ME400C spread the same 1366x768 resolution across 11.6" and 10.1" panels, respectively.)
These normalized numbers show the A4-5000 actually comes very close to the Zenbook in the web-browsing run—and it's substantially better in the video playback test.
If all of these systems had a 50Wh battery, the Kabini whitebook would have stayed up 6.9 hours in the web test, compared to 7.4 for the Zenbook. That's a rather small difference. Both runs are also within spitting distance of the "all day battery life" nirvana.