iPad users who want to ensure they're getting a full charge every time they plug in should wait up to an hour after the device shows 100 percent. That's according to Dr. Raymond M. Soneira, creator of DisplayMate and author of a new report about the third-generation iPad, who says the device continues to charge well after the OS shows that it's reached full capacity.

We put the third-generation iPad's battery through a... battery of tests as part of our review, finding that we were often able to get more than the advertised 10 hours of life when watching video, and a bit less when surfing the Web, reading, and performing other activities. We inadvertently ended up charging the iPad for much longer than we thought was necessary for each run, however. According to Soneira, users should be doing that if they want to get maximum life out of their new iPads.

"I measured the power actually drawn by the AC Adapter and found that the new iPad continues to charge for up to 1 hour after it claims to reach 100 percent," Soneira told Ars via e-mail. "This affects the battery run time if you stop charging when it says 100 percent. Other tablets and smartphones also lie about their charging status, so if getting maximum battery run time is crucial, people need to keep their devices recharging for longer than the screen claims."

We recently published a guide for those looking to milk as much life as they possibly can from their iPad batteries—our tips included keeping your screen brightness to a minimum, turning off wireless settings when you can, minimizing push notifications and iCloud syncing, watching videos locally instead of on the Internet, and caching your documents so you can read them offline. But if you're not charging up your device to its maximum capacity as Soneira suggests, you could be losing out on those last handful of minutes that could save you from missing a deadline or some other emergency.