When your iPad says that it's powered up to 100%, the device indeed may still be charging. That's because of how the batteries in iPads and other Apple iOS devices work — once they reach a full charge, they discharge a bit. The battery then begins a cycle of charging and discharging at near-full power until its unplugged.
"The circuitry is designed so you can keep your device plugged in as long as you would like," says Apple VP Michael Tchao. "It's a great feature that's always been in iOS." The bottom line here: When your iPad or iPhone says it's at 100% power, it's not actually at full power. That battery indicator, while a good rule of thumb, isn't really a legitimate measure of anything.
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