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Apr 12, 2001
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Among the many topics related to charging, battery, and heat issues with the new iPad, observers have noted that the device continues to charge for up to an hour after the point at which the iPad reports a charge level of 100%.

ipad_3_battery_life.png

AllThingsD has now spoken with Apple's Michael Tchao about the phenomenon, with Tchao noting that it is simply an effect of the same trickle charging feature that has always been included in iOS devices.
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.

Article Link: Apple Explains New iPad's Continued Charging Beyond 100% Battery Level
 

smileyborg

macrumors 6502
May 12, 2009
267
0
This makes sense. People need to stop freaking out.

Li-Ion batteries don't fare well when they are held at a 100% charged state (or 0% for that matter) for extended periods of time. By allowing the battery to charge and drain a small amount continuously while plugged in, the life of the battery is extended significantly.

Basically, Apple is setting "100%" to be less than the actual capacity of the battery (and has defined 100% as the "rated" battery life) -- so you could actually see better results when your battery is actually charged "beyond" 100%.
 
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WannaGoMac

macrumors 68030
Feb 11, 2007
2,538
3,780
So this seems to be official confirmation that keeping iOS devices plugged in all the time doesn't hurt long term battery life... This has been hotly debated for years!
 
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Risasi

macrumors 6502
Sep 16, 2011
338
0
:lightbulb:

I always wondered why sometimes on my iphone and ipad it would take to take forever to come off of 100%. Other times it was pretty quickly.
 
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baryon

macrumors 68040
Oct 3, 2009
3,621
2,029
I'm pretty sure the MacBooks do that too.

Just out of curiosity: why can't the electricity from the charger simply bypass the battery and power the device directly once it's fully charged? That way, the battery would not discharge, and would not need to charge/discharge constantly, no?
 
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azentropy

macrumors 68030
Jul 19, 2002
2,640
1,929
Surprise
As they mention, it has always been like this. I've noticed this myself with previous iPads and iPhones. Charge will be at 100% and I'll use it for 10+ minutes and it still lists at 100%. Other times it drops to 99% after a minute or so.
 
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Dr McKay

macrumors 68040
Aug 11, 2010
3,425
46
Kirkland
So this seems to be official confirmation that keeping iOS devices plugged in all the time doesn't hurt long term battery life... This has been hotly debated for years!

Good, because most of the time my iPhone charges in an hour, and then remains plugged in the other 8 hours while I sleep. :)
 
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jephrey

macrumors regular
Dec 19, 2005
207
56
I'm glad this was finally explained. I'm an EE, this makes complete sense. Not as if I was worried otherwise, I assumed it was something like this.
 
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andreiru

macrumors 6502
Apr 18, 2008
355
94
Kurgan, RF
My new iPad holds charge extremely well. Unplugged early morning, plugged back late night with still charge left despite heavy usage. Having read about how best to charge, came to conclusion to keep unplugged during day and charge at night. As learnt that iPhone cable charges slower than iPad cable that came with the device. Awesome battery life. Especially when compared to the iPod touch 4g that lasted less than half a day and often just a couple of hours after a year (sometimes even less).
 
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Mortalias

macrumors 6502
Aug 24, 2011
354
3
Los Angeles, CA
Glad to know this puts rest to the debate about leaving iOS devices plugged in, and whether or not it was harmful to the battery.

Keep on keeping on, Apple!
 
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HarryPot

macrumors 65816
Sep 5, 2009
1,001
397
I'm pretty sure the MacBooks do that too.

Just out of curiosity: why can't the electricity from the charger simply bypass the battery and power the device directly once it's fully charged? That way, the battery would not discharge, and would not need to charge/discharge constantly, no?

It would be pretty great if someone clarified this on MacBooks.

So many people keep telling me that I can't leave my Mac connected all the time. Because the battery would start losing it's health. I've always said that is BS. But it wouldn't hurt to be sure of it.

As for what you said, it has to be with keeping the health of the battery, supposedly.
 
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TheBronx

macrumors regular
Mar 12, 2012
236
0
nodemandbecauseoflackoflinesgate, done.
heatgate, done.
batterygate, done.

head over here for the next gate...notreally4Ggate hehe :D

it never gets old all the silliness!
 
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el-John-o

macrumors 65816
Nov 29, 2010
1,415
559
Missouri
I'm pretty sure the MacBooks do that too.

Just out of curiosity: why can't the electricity from the charger simply bypass the battery and power the device directly once it's fully charged? That way, the battery would not discharge, and would not need to charge/discharge constantly, no?

If the battery is constantly at 100% it's lifespan will be shortened (meaning the number of times it can be recharged). By discharging and recharging like this, it'll last longer. That's why Lithium batteries (both Li-Ion and LiPo) have had "battery cyclers" on the market for as long as they've been around.
 
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mattraehl

macrumors 6502
Feb 26, 2005
384
1
I've always left my iOS devices plugged in overnight, I didn't know this was controversial? Some people are way to hyperactive about their electronics.
 
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writingdevil

macrumors 6502
Feb 11, 2010
254
32
I read a lot of complaints when this came out, and it wasn't just Apple haters, but so called Apple experts who like to comment using their (often) uninformed opinion to be heard (somewhere) that day. Of course, the media bloggers pick up how many hits the piece gets, then reports it, then the major media pick up on the bloggers and it gets on the evening news, late night jokesters and on and on. Arrrggghhh! (I'm contributing to hits, just wish there was an up or down vote on the article itself, not just the comments, of course that could wind up confusing 'bloggers' who don't have time to read and research their "news" and muddle things up more.)
 
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Lokheed

macrumors regular
Jun 10, 2009
202
0
So this seems to be official confirmation that keeping iOS devices plugged in all the time doesn't hurt long term battery life... This has been hotly debated for years!

I never saw this behavior with my 3G. But I noticed it right away on my 4. The percentage would dip down as far as 96, and then charge back up to 100%. On my 4S, the effect is magnified. I have seen it drop as low as 92% and TBH, it rarely sits at 100% (and in a fully charged state), spending more time dropping to the 90's and then back up again.

The downside to this is that sometimes you will unplug your device to use it in a less that fully charged state. A trade-off I suppose.
 
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