5 Replies Latest reply: Nov 20, 2009 12:14 PM by Done that
Megamark Level 1 Level 1 (0 points)
My Iphone 3GS has suddenly started using up the battery at the rate of about 20% per hour while doing nothing (reboot and let it sit). The phone was working perfectly until this past Wednesday night. I have not changed anything on the phone (no OS updates, etc.) other than I noticed that 5 or 6 apps were updated that evening. How do I figure out which of my apps were updated on Wednesday night so I can delete them and then add them back one at a time in order to figure out which one is causing the problem. Notifications on the phone is set to off. Much thanks.

Iphone 3GS, iPhone OS 3.1.2
  • paulcb Level 6 Level 6 (19,095 points)
    From an iPhone standpoint, I'm not sure what you mean by rebooting but try resetting (not restarting) your iPhone by pressing the home and sleep buttons until you see the Apple logo, ignoring the slider. Takes about 5-15 secs of button holding and you won't lose any data or settings.

    This will clear your memory, including the offending app, if there is one.
  • henley_regatta Level 1 Level 1 (40 points)
    I think you've self-diagnosed the problem (updated app causing drain) correctly, and the fix is a reset (hold power+home for 10-15 seconds BEYOND the "swipe to power off" prompt and the phone will hard power off) to clear memory.

    HOWEVER, I've observed wierd *battery gauge* behaviour (as opposed to battery behaviour) where the drop in reported percentage is most non-linear but the actual battery life still meets expectations. It might be worth doing a couple of full-charge to fully-empty (iPhone powers itself off) cycles to allow the power monitoring gubbins to sort itself out....
  • xXTheTenXx Level 1 Level 1 (0 points)
    The biggest mistake is to ascribe this issue to the 'reset the phone and it will go away' solution...

    Read around the forums.

    Lots of people are experiencing 'sudden excessive battery usage'... the mistake most are making is in assuming that this means that the battery is crappy, or that there's a mere glitch in the OS...

    You need to start identifying common characteristics of this problem, and if you don't have it already I strongly suggest you get System Activity Monitor installed on your iPhone.

    The 'battery drain' you refer to is, I will bet money, associated with a cycle of sudden bursts of CPU activity on your iPhone which indicates that the phone has entered a loop of spurious activity. If you have System Activity Monitor, you'll be able to pull up a CPU meter and see this activity. The CPU spiking eventually leads to the phone getting warm to the touch, and will continue until either you stop it, reset the phone, or the battery runs out, and it will be identifiable by the 'sudden excessive' draining of the battery. 'Stopping it' is dependent upon actually being able to identify the root of the problem and controlling or fixing the issue, which is what we're all trying to do. Resetting the iPhone works every time, but for how long is another issue... I've seen the problem recur consistently between 2-4 minutes after the restart of the iPhone. You'll usually find that switching wifi off on the iPhone will cure the CPU bursting problem, but actually it only masks the issue, and the 'bursts' of CPU activity appear to be associated with network activity which simply switches from WIFI network to the 2G/3G data networks when wifi is turned off, which in some cases will drain your battery even faster, even though the CPU usage has dropped a great deal.

    We need to establish some points of commonality...

    Are you using wifi with the iPhone, presumably running a wireless router/wireless network at home?

    Do you see the CPU usage bursting to 100% (excessive) continually while you see this 'battery drain' (you'll need System Activity Monitor for this bit)

    Does the CPU usage drop dramatically when you switch off wifi?

    Are you using the Calendar application?

    Do you use Calendar to synchronise calendar/contact data with some kind of server somewhere?

    If so, which platform are you synchronising with? Exchange? Gmail? MobileMe? etc. etc.

    If you use the Calendar application, do you notice that in the top of the screen, next to the wifi signal icon, there is a spinny 'loading' reminder type icon, and do you see it light up about 4-6 seconds after you open Calendar with wifi connected? Does the disc spin once and go away, or spin and then keep reappearing and spinning again like it is stuck in a loop? If you see this, then switch to system activity monitor and check the CPU usage. You'll probably find that the CPU usage is spiking again. It does appear that Calendar, particularly in a synchronisation scenario, may be the trigger. If you don't use Calendar at all, we need to know, because it means we're looking for a trigger elsewhere or as well as Calendar. Calendar issues may, after all, just be a symptom. It could be a wifi issue with the iPhone.

    If we can start to compile some solid answers to these issues and compare notes/incident characteristics, maybe we can lead Apple by the hand to a serious solution.
  • Megamark Level 1 Level 1 (0 points)
    Thanks for all the assistance. No of the recommended solutions ended up providing any long term relief. I ended up restoring the phone and then syncing all of my info and that solved the problem.
  • Done that Level 1 Level 1 (25 points)
    I had to restore mine also, I tried many suggestions but none would solve it so I had to restore and not use my backup either. I did it about a month ago and all has been fine since.