Apple's iPad and iPad Mini took top honors in a pair of tablet battery shootouts conducted by consumer watchdogs in the U.S. and the U.K.
Consumer Reports, in the U.S., and Which?, from the U.K., have recently run dozens of tablets through tests to determine how long the devices' batteries last between charges.
"Apple wins this category by quite a margin," said Which? researcher Tim Gee in a Tuesday blog about the group's 10-in. tablet tests. In the 7-in. category, Gee said the iPad Mini was "still ahead of the game."
Computerworld averaged the time-trial results of Consumer Reports and Which? to arrive at a final score for a dozen tablets, ranging from Samsung's hot-selling 7-in. Galaxy Tab 2 to Microsoft's struggling 10.6-in. Surface RT.
The fourth-generation iPad's battery lifespan of 13.2 hours easily beat the competition in the larger-sized category, exceeding Sony's Xperia Tablet S (at 9.9 hours), Google's Nexus 10 (9.5 hours) and the Surface RT (9.5 hours.) The older-but-still-sold iPad 2's battery lasted 10.7 hours, coming in second.
In the 7-in. classification, the iPad Mini's 11.7 hours topped Amazon's Kindle Fire HD (10.3 hours) and Google's Nexus 7 (9.3 hours). The poorest-scoring small tablet measured by both watchdogs, Amazon's Kindle Fire, scored just 7.4 hours, or 37% less than the Mini.
The Surface's battery lifespan made news last week when Microsoft acknowledged that the upcoming Intel-powered Surface Pro will run about half as long between charges as the already-shipped Surface RT.
The Surface Pro, priced at $899 and $999, will go on sale next month, Microsoft has said.
Although no one outside the Redmond, Wash. developer has a Surface Pro, the Surface RT tests conducted by Consumer Reports and Which? can be used to ballpark the Pro's expected battery life.
With an average Surface RT battery lifetime of 9.5 hours and Microsoft's 50% admission, the Surface Pro will run for approximately 4.7 hours before requiring an electrical outlet.
Bloggers and other pundits who have knocked the Surface Pro's battery life have good reason to denigrate the tablet, according to Consumer Reports and Which?: The Surface Pro will last just 36% as long between charges as a Retina-equipped iPad, and its battery will be exhausted 8.5 hours before the one in Apple's iconic tablet.
Consumer Reports and Which? both tested tablet batteries by browsing over Wi-Fi, with power-hungry features, such as Bluetooth, disabled, and screen brightness set to lower-than-maximum levels.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His email address is email@example.com.