DisplayMate creator Dr. Raymond M. Soneira did a test on the iPad battery and discovered that the iPad continues to keep charging even after hitting 100% on the battery indicator. In his tests, the iPad kept charging for up to an hour after hitting 100%. Soneira also discovered that they were often able to get more than 10 hours of battery life when watching video, but less when surfing the web and reading.
“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,” stated Soneira in an interview with Ars Technica. “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.”
For people that want to get as much battery life as possible, it is recommended to keep screen brightness down, minimize push notifications, minimize iCloud syncing, and watch videos locally instead of on the Internet.