iPhone iOS 9.2.1 battery drain for no reason

Discussion in 'iOS 9' started by iOSUser7, Feb 21, 2016.

  1. iOSUser7 macrumors 6502a


    Jun 23, 2014
    Hi everyone,

    I just upgraded to iOS 9.2.1 (13D20, the second revision that fix error 53) on my iPhone 6s from the original iOS 9.0 that shipped with the phone, 4 or 5 days ago (can't remember exactly). I thought I had the worst iOS version ever released (iOS 9.0) but I guess I was wrong.

    Now I'm experiencing some severe battery drains. Let me give some examples.

    This night, I went to sleep with my phone at 100%, and while I would previously wake up at that same percentage (or worst case at 99%), I woke up with 91%. I was like WTF, what is that so I went checking the battery usage and I noticed that the mail app had 1.5 hours of standby time with only 1 min of active usage. How can that be possible, I open this app like once a day.

    Also, I noticed that since the upgrade, standby and active usage time are always the same. So if I have 6 hours of usage, I will have 6 hours of standby. This can't be possible, there is clearly something wrong here.

    Does anyone have/had the same problem as me ? Any tips of how I can fix it before I try the (long) process of backup/restore ?


  2. arubinst macrumors 6502

    May 26, 2008
    Lausanne - Switzerland

    I had the very same problem you are having, but with an iPhone 6 plus. This happened to me when I updated to 9.1 (not 9.2.1). I had exactly the same standby and active usage time for my battery.

    Backup/restore didn't work for me. I restored 3 times (twice in DFU mode), I deleted Facebook and a bunch of other apps but kept having the same problem. Finally, I figured that some iOS process could be the cause of the battery drain. Email, App Store, FaceTime, iCloud and iMessage were all good suspects... So I reset them all!

    In the end, I ended up doing all this and it solved my problem. Of course, YMMV. You can only do this if you sync using iCloud or some other service (my particular case is with iCloud). Otherwise, you will loose your contacts and calendar data. If you use an email account with POP3, you may also loose those emails. Exchange and IMAP should be fine.
    • Make a backup of your phone on iCloud or iTunes just in case (enable backup encryption in iTunes to keep your passwords in case you need to recover from your backup)
    • Delete all your email/contacts/calendar accounts. Basically, you want to have an empty Mail, Contacts, Calendars entry in your settings
    • Sing out of iTunes & App Stores
    • Sign out of iCloud. Confirm that you want to delete contacts information and any other warning you receive
    • Deactivate Facetime
    • Deactivate iMessage
    • Reboot your phone
    • Sing into iCloud (this will get you back your contacts, calendar, notes, etc.)
    • Activate FaceTime, iMessage
    • Sing into your iTunes & App Stores
    • Reconfigure your email accounts
    This all seems like a lot of work but it shouldn't take you more than 5 minutes.

    Let me know how it goes if you feel like trying.


  3. Ashin macrumors 6502a


    Jun 19, 2010
    First thing I'd do is remove all of your email accounts and re-configure them. Also check Push/Fetch settings - 1.5 hours background usage over night seems excessive to me (personally I have all my email set to manual, but I can imagine a frequent Fetch could rack up time, or a broken Push...).

    If that fails, I'd Reset all Settings in Settings - this is the least painful fix before more extreme full restores that take much longer (just need to re-configure your settings which maybe takes 5-10 minutes).

    I've had a lot of success with doing a Reset all Settings - just don't do the Erase all Content one.
  4. Shadowbech macrumors 601

    Oct 18, 2011
    Planet iPhone
    Definitely do the hard reboot first by pressing the home button and the power button for 30 seconds until the apple logo appears. I notice my wife's phone doing this sometimes where usage and standby time are the same. I simply hard reboot the device and that generally fixes the problem.
  5. iOSUser7 thread starter macrumors 6502a


    Jun 23, 2014
    Alright thanks a lot guys, I'll try that if the hard reboot doesn't fix my issue, I'll report back.
    I tried the hard reboot thanks, I already tried a simple reboot but maybe the hard one will fix my problem. I'll report back later.
  6. iOSUser7 thread starter macrumors 6502a


    Jun 23, 2014
    Quick update. The hard reboot fixed my problem, I now have different screen on and background time and the battery life is much better now. :)

    If this issue ever come back, I'll do the remove mail accounts etc method.

    Thanks for the help guys. ;)

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