New iPad Battery Keeps Charging Despite 'Battery Full' Message

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You shouldn’t stop charging your new iPad as soon as it shows a 100 percent battery. Instead, to get the most from the battery, keep it charging for at least another hour after it says it is full, a study on Apple’s new tablet finds.

In his review of the new iPad Retina display, Dr. Raymond Soneira of Displaymate Technologies discovered that the third-generation iPad continues to draw 10 watts of power for about an hour, even after iOS claims the battery is 100 percent charged and says it is done charging.

To power the high-resolution display in the new iPad, along with improved quad-core graphics chip, Apple bumped the battery size and output by 70 percent, a teardown of the new model reveals. The new iPad has a 42.5-watt-hour battery, compared to the 25-watt-hour Lithium-Ion battery found in the iPad 2.

The bigger battery takes a toll on the new iPad, though. It’s slightly thicker and heavier than the previous model, and some tests indicate it also runs hotter than its predecessor. Apple on Tuesday denied any overheating by the new iPad, despite concerns.

However, the findings from Dr. Soneira confirm what the first users of the new iPad may have already noticed: The bigger battery also requires almost twice as long to charge. For optimum charging, don’t unplug it immediately after it says it is 100 percent charged. Dr. Soneira measured the power actually drawn by the AC adapter and found the tablet continues to charge for up to an hour after it claims it reached 100 percent -- meaning leaving it in longer than purportedly necessary is the way to get the most out of a charge.

What level of brightness setting gives you the longest battery life is also another interesting finding from the study. Of course, you could put the brightness all the way down to conserve power, but that wouldn’t work well in lit rooms. Dr. Soneira determined that keeping the brightness slider just in the middle supports up to 11.6 hours of use.

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At a Glance
  • Apple's third-gen iPad is defined by its amazingly sharp and crisp high-resolution display, as well as its option for 4G. The heavier weight is a disappointment; but the display, coupled with Apple's solid app ecosystem, makes this tablet the one to beat.


    • 4G LTE option via Verizon
    • Vivid, high-resolution display


    • iOS 5.1 still lacks large-screen optimizations
    • Slightly increased weight
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