Apple Explains New iPad's Continued Charging Beyond 100% Battery Level: So, here’s how things work: Apple does in fact display the iPad (and iPhone and iPod Touch) as 100 percent charged just before a device reaches a completely charged state. At that point, it will continue charging to 100 percent, then discharge a bit and charge back up to 100 percent, repeating that process until the device is unplugged.
Doing so allows devices to maintain an optimum charge, Apple VP Michael Tchao told AllThingsD today.
“That circuitry is designed so you can keep your device plugged in as long as you would like,” Tchao said. “It’s a great feature that’s always been in iOS.”
Tchao notes that users can expect 10-hour battery life on the new iPad regardless of when in that trickle charge/discharge cycle they unplug their device, and that Apple intentionally displays the battery level at 100% throughout that cycle so as to not confuse consumers who might otherwise think their device is not completing charging correctly.