All iOS Devices Lie When They Say Their Battery Is 100%

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Although it takes forever to fully charge, the new iPad costs less than $2 a year to run.
Unplug your iPad just after it reaches 100% and you'll lose up to 1.2 hours of battery life.

Shortly after the new iPad made its debut earlier this month, it was discovered that the way in which the device calculates its battery life is flawed. Despite telling you its charge is at 100%, your device hasn’t actually finished charging.

New data proves that in fact, your device isn’t finished charging until more than two hours after it reaches “100%,” and if you unplug it before then, you could lose around 1.2 hours of battery life. What’s more, it seems all iOS devices misreport their battery life.

The reason for this — as you may have guessed — is that the new iPads battery algorithm is “busted,” as ZDNet puts it. Ray Soneira, President of DisplayMate Technologies, did a little investigating and discovered that the new iPad will run for around 11.6 hours on a full battery. But its running time based on the 100% indicator is just 10.4 hours.

That’s a loss of 1.2 hours, or nearly 10%, if you unplug your device just after it reaches 100%.

According to ZDNet, Apple’s algorithm has always reported 100% battery life at a slightly lower capacity — normally around 97% — to keep the battery “safe and healthy.” It’s the same story for all of its mobile devices. The reason it’s more noticeable with the new iPad is that it features a much bigger battery:

The battery on the new iPad is huge, with a total charge capacity of a massive 42Wh or measured another way a monstrous 11,666 mAh. A 3 percent safety margin for the iPad 2 battery would be equal to around 210 mAh, while the same safety margin for the new iPad would be equal to 350 mAh.

When the new iPad first displays a 100% charge, it’s actually only holding around 90%, according to the report, and you’re getting 1.2 hours less runtime. It’s best to leave it charging overnight to get the maximum runtime the next day.

Soneira also found during testing that it takes around 5.5 hours to charge the new iPad when its battery is completely run down. That sounds like a lot, but try using the device at the same time and you’ll increase that charge time to a whopping 20 hours.

Because the new iPad’s battery is so big and it suffers from this issue, ZDNet expects to see Apple’s algorithm changed in a future software update, so that the device does show 100% until it actually reaches 100%.