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I love to play games and do other tasks that quickly drain the iPhone's battery. Sometimes I'll use the phone while plugged into a power supply. Does the iPhone still use the battery when performing these high-performance tasks while connected to the power source?

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up vote 2 down vote accepted

Although Nathan has a valid point for wall charging, from personal experience it is possible to discharge the battery while it is plugged into a powered USB port.

Even though my iPod Touch 2nd Gen was plugged into my MacBook, playing Need for Speed Undercover was sufficient to cause the device to power down due to low battery. It seems that a powered USB doesn't provide sufficient charge to offset the drain caused by a graphically intensive game.

To sum up: if you are worried about exhausting the battery while charging, use a wall charger.

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How old is the MacBook? Was the port on a keyboard/hub? – Nathan Greenstein Jan 19 '11 at 5:20
Its a Macbook Pro I purchased August of 2010. It was plugged into one of the USB ports on the Macbook itself, no keyboard or hub of any kind in the middle. – Ryan Wersal Jan 19 '11 at 5:22
I've noticed the same thing here. Seems like the wall charger is the only that support the device in heavy use. – Keyne Viana Jan 19 '11 at 9:23

When you're plugged in to a power source, the iPhone will not use the battery unless for some reason you are using more power than the charging source can provide.

Normally, unless some process is hitting the CPU and GPU and all radios (such as a GPS mapping app), even a computer USB port at 500 mA will both power your games/apps and charge your battery at the same time.

Even if your game takes more current than the charge is providing, using all the wall power will reduce the amount of battery being consumed which will certainly save your battery.

Of course, you should expect hundreds of full charge/discharges and as long as you are one a month draining the battery, you don't need to keep the electrons moving otherwise for good battery lifespan and health.

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Thanks. Is there a link on apple site describing this? I can't find nothing about. – Keyne Viana Jan 19 '11 at 3:44
I don't believe this is documented, but you can see for yourself. Once you plug it in to charge, you'll see the lightning bolt icon in the battery. That means it's charging. Notice that it stays there even during heavy use. You can also try plugging it in with the battery partly empty, then using it for a while (a half hour, to be safe). Once you unplug it, the battery level will be higher. – Nathan Greenstein Jan 19 '11 at 4:04

nonsense , the icon means nothing , i have my phone at 100% with the plugged in icon , i use it for awhile it goes back to lightning icon , i use r more it goes down to 99% , at 96% now having used it plugged in since 100% watching stuff in YouTube multitasking iPod etc

it shows Apple electronics suck that they are clever enough to implement this - or they prefer batteries have shorter life , to charge you more money

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Could you edit this to more clearly answer the question? This seems more a comment about another answer which we do restrict until you've gotten a few up votes. Just click the edit button and see if you turn your criticism towards whether using Apple connected to power saves the battery. – bmike Mar 21 '13 at 15:26
This actually seems to agree with Nathan's answer - under heavy load, the battery may discharge even though it's plugged into a power supply. – Dan J Mar 21 '13 at 16:24

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