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sk0rp10 Author

Level 1

24 points

iPhone 4S battery issue detected (really)

Dear all,

I'm an Italian engineer and iOS developer, who recently bought the brand new iPhone 4S .

As most of you who have bought such device , I'm experiencing poor battery performances , even after the latest 5.0.1 iOS update from Apple.

Therefore I wanted to try to understand what was the real cause of such bad performances and - moreover - why does it seems that only certain iPhone 4S are affected from such battery inefficiency behaviour.

By looking at the Internet, most of the hints lead to the conclusion that a particular mix of Apps - or even just one App ( you may find many pointing at Facebook or Fousquare Apps as culprits for the bad battery performances) may cause this huge power drain.

The only way to match such apparently contrasting reports from users all over the world with the fact that at least one certain cause shall explain the power drainage exeperiencied by us all was - in my mind - to find a solution in what the Apps could do to make things go wrong.

By using the Apple Instruments tool from Apple Developer suite (shipped with XCode) , I found this interesting thing :

it seems that the very cause of battery drainage is a bug in the video card driver , which could be triggered by applications making use of certain iOS APIs.

I found this by looking at the energy consumption graphs extracted from my iPhone 4S and comparing them with other information taken from the device.

It seems that - even in sleep state - and when nothing should use the GPU, there is recorded video card activity. But the most interesting thing is that it seems the device does not recognizes this activity as a power draining activity, therefore my theory is that iOS can't trigger power saving algorithms to shut down the video card since it can't detect the fact it is consuming battery power.

I will attach here a screenshot taken from Apple Instruments tool which shows a 17% video card activity while energy usage is recorded as to be zero, and even when the Display Brightness is exactly zero, there's still video card activity ( near 1%) , but still no energy consumption is recorded by the iPhone.

I'm writing all this here hoping that Apple will examinate my theory and - if confirmed - will soon release a fix for this annoying issue.

iPhone 4S, iOS 5.0.1, Battery bug

Posted on Nov 14, 2011 12:31 PM

22 replies

xlinux

Level 1

0 points

Nov 25, 2011 11:15 PM in response to sk0rp10

Hi all,

i'm following this thread to understand if my iPhone 4S has battery drain problem or other. My iPhone with iOS 5.0.1 has lost 10% of battery in half hour in idle, could be broken?

sk0rp10 Author

Level 1

24 points

Nov 26, 2011 12:48 AM in response to xlinux

Hi xlinux,

your iPhone is certainly experiencing an abnormal discharge rate, which is about 6x the normal one.

However it is not "broken" , simply one of the Apps that were launched on it accessed the bugged part of

iOS. This event triggered the resource release bug. To stop drainage just follow the steps suggested few posts before ( close all apps , then soft reboot ).

This is obviously not a solution to the problem , which has to be fixed by Apple, rather than a simple workaround which can let you use the iPhone as normally as possible.

JMcC24

Level 1

5 points

Nov 26, 2011 11:26 AM in response to sk0rp10

I just got my new 4s on Tuesday. I was not having any battery drain issues until yesterday. I installed a Xbox Live app (360 Live) and by the end of the day the battery was pretty much drained, even though I was at work with my phone just sitting on my desk all day. After finding this post and knowing that the only change I had made was installing that app, I deleted it, closed all background apps and did a soft reboot. Battery life is back to normal. So I must agree that there are some apps that trigger this problem. Just thought I would share this so maybe it would be of use to others having battery issues.

zeGenius

Level 1

12 points

Nov 27, 2011 12:25 AM in response to JMcC24

HI JM,

Thanx for sharing your experience. Hopefully more and more 4S owners with pathetic battery performance can try this step and benefit from it

Also: as we've been pointing out, this (close all apps + soft boot) is certainly not a final solution, but is just a workaround until Apple engineers can fix this problem for good

With luck, you'll be able to 360-live again soon on your 4S! 🙂

Cheers,

Neil

xlinux

Level 1

0 points

Nov 28, 2011 10:33 PM in response to sk0rp10

Hi,

sorry for delay, thank you for the answer, i hope that Apple fix soon the bug.

Feb 27, 2012 8:27 PM in response to sk0rp10

Hey sk0rp10,

I got 4S 4 days back and I was wondering whether I got a faulty piece.

this really worked for me. thank you very much!!

my battery was showing 72% before this workaround. i followed the above steps and after 3 hrs, it still showed 72% and then i turned ON all the services except Siri and still after 1hr, it is showing 72% !!!

you are the hero!

awsome 🙂

Jun 24, 2012 2:55 AM in response to sk0rp10

I have noticed on my iPhone something different. When the wifi is turned on and after a 15min of standby for the iPhone, the wifi stops working to prevent battery drain. As a result, if you have 3G on, the device will switch automatically to 3G network in standby. However, when you wake the iPhone it will switch back to wifi, in lightning fast. So, turn off 3G when you don't need it

iPhone 4S battery issue detected (really)