Apple's iPad and iPad mini smoked the competition in battery life, according to test results released by British magazine Which? The consumer reporting magazine put devices with 9.4-inch screens and larger against one another, and then those with screens smaller than 7.9-inches, and Apple's iPad family took top honors, crushing top Android and Windows 8 devices.
For tablet battery tests, Which? set the brightness for each device at 200 nits, which it called "a reasonable daytime brightness level." The testers use a light meter to measure brightness in order to ensure that each device is being tested under the same conditions. The tests then measure battery life at that level while Web browsing over Wi-Fi and 3G (where appropriate), as well as video playback.
They also test recharge time, but those results weren't included with this report.
The Big Ten Inch
As shown in the chart below, Apple's iPad with Retina Display (iPad 4) laid the smackdown on every competing device. At 811 minutes (13.5 hours), its nearest competitor was 2011's iPad 2, at 590 minutes (9.8 hours). Sony's Experia Tables S was third at 534 minutes (8.9 hours) and Samsung's Galaxy Tab 2 10.1 was fourth at 532 minutes, just below the Sony device.
Microsoft's Surface RT took fifth place 501 minutes (8.35 hours), while the Google Nexus 10 was sixth with 488 minutes (8.1 hours). Note that the average was 451, well below sixth place Google, but that's because not all of the tablets tested were included in the graph or the blog post announcing the report.
The Asus Eee Pad Transformer Prime did very poorly in the tests, showing only 335 minutes. This has been a popular device for Asus, part of that company's belief that people really want their tablets to be toaster-fridges.
The Eee Pad Transformer Prime comes with a separate keyboard that has a second built-in battery, dramatically extending the device's life when one is using it as a laptop. Which? tested the device in both modes, with the 335 minute results representing the tablet-only (sans keyboard) mode. With the keyboard attached, it tested at 661 minutes, enough for second place to the iPad with Retina Display, but it's not actually a tablet and weighs some 2.4 pounds, so pick your poison.
In the chart below, we see the results for the 7-inch family, devices with screens 7.9 inches and smaller. Once again, Apple's iPad mini spanks the other devices with 783 minutes of battery life (13.05 hours). Amazon's Kindle Fire HD was a distant second at 591 minutes (9.85 minutes), and the Google Nexus 7 came in third at 550 minutes (9.16 hours).
The average of the 7-inch family was 478 minutes (just under 8 hours), with the new version of last year's Amazon Kindle Fire (437 minutes) and the Samsung Galaxy Tab 2 7.0 (425) coming in below that average.