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New iPad Battery Problem Is A “Feature”


Apple iPad 3rd generation
The iPad’s battery meter may not always tell the whole truth

Everyone seems to love finding chinks in the armour of a much-hyped new device. Sometimes there are genuine widespread faults, others are merely quirks of design and within “operational expectations” or words to that effect. The latest is the new iPad and its battery.

With Apple’s new third-gen iPad, the first grumblings were about it getting slightly warmer than the iPad 2. This was quickly exaggerated by some people as “overheating”, if your idea of overheating is about as hot as a mug of lukewarm tea.

Now tech analysts at DisplayMate have identified possibly strange behaviour with the iPad’s battery charging, saying that it carries on charging for an hour even when the display reads 100%.

Now, with The Apprentice back on our screens at the moment, it would be easy to jump to the conclusion that the iPad battery can somehow give you 110%. What’s more likely is that it’s only about 90% full when the display says it’s done. So if you want to be sure of absolute maximum charge, keep it plugged in a while longer.

Apple iPad 3rd generation

According to AllThingsD, all iOS devices show a 100% charge just before finishing, then they continue until completely full, then if still plugged in they will discharge a little and charge back up to 100%.

Apple vice president Michael Tchao told the site, “That circuitry is designed so you can keep your device plugged in as long as you would like. It’s a great feature that’s always been in iOS.”

So there you have it. It’s not a mistake, it’s a feature. And while it could be slightly confusing or misleading even, it appears to be there to protect the battery from overcharging.

The new iPad battery has a much higher capacity than its predecessor (11,666mAh compared to 6944mAh) but it also takes substantially longer to recharge. At least the resulting battery life is still decent at about 10 hours, depending on what you’re using it for.

Via AllthingsD

Go to comments

A Scotland

March 28, 2012, 5:56 pm

My understanding is that it is not just all iOS devices, but all battery powered devices that operate in this way. I wonder if DisplayMate where perhaps just looking for some cheap publicity?

If true this also makes Apple's press office look ridiculous for claiming it as a feature. Maybe they will call it iTrickle.


March 28, 2012, 8:05 pm

Modern battery chargers are highly complex devices, constantly altering the charge current for maximum efficiency. This prolongs the life of the battery while allowing the user to keep the charger plugged in for longer than they strictly need to charge the device. I wouldn't be surprised if virtually all Lithium Ion chargers operate in a similar manner, and have done for years.

The charge state displayed by the device is actually quite artificial, and has been calculated in a fashion that makes it appear more linear than it really is, just to make its behaviour easier to understand for the user. If the phone were reporting the true charge state of the battery, most users would find that highly confusing, and would almost certainly describe it as a 'fault'. Ironic, really.


March 28, 2012, 8:29 pm

From my distant memories of physics lessons, rather like capacitors, most rechargeable battery tech recharges in a very non-linear fashion. Charge is taken up very easily/quickly by an empty battery, but as the battery 'fills' a resistance gradually builds that causes the charging rate to effectively slow down - rather like the increasing difficulty you experience when blowing up a balloon.

Modern chargers clearly use some clever techniques to help counteract this effect to some degree, but even Apple "can-nee change the laws of physics".

James Reckitt

March 29, 2012, 2:12 pm

That sounds like a really silly way of doing it. Why don't they just bypass the battery unit and get a direct feed from the mains once it's charged? That way you wouldn't use up precious charge cycles.

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