Last week, we reported that the new iPad continues to draw power even after the iOS battery indicator reports 100% charge.
This led to speculation that there was a bug in iOS battery indicator. But, it looks like the behavior is nothing new to iOS devices. You should ideally notice a similar behavior while charging an iPhone or iPod touch.
Apple’s VP Michael Tchao has clarified to AllThingsD that this is not a bug, but it is feature of iOS to maintain optimum charging when the device is plugged in.
Here’s how it works:
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.
The discharging and charging of battery has been one of the source of the confusion. But Tchao explains that it is being done to keep your iOS device plugged in as long as you like:
“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.”
No matter where in that cycle a battery is, Tchao said, owners of the new iPad can expect the 10 hours of battery life that Apple has promised.
The decision not to keep changing the battery status was designed so as not to distract or confuse users.
That explains why iPad 3 continues to draw power after reporting 100%.
It is strange that we haven’t noticed this before, but it is probably because the new iPad comes with a huge battery and this discharging and charging process when it is plugged in is more noticeable than previous iOS devices.