1. cybernutte's Avatar
    I'm running KitKat 4.4.2 on my Nexus 7 (2013). I usually have no huge battery problems, but for the last two nights the battery has dropped about 40 points overnight, with wi-fi off. Last night, when I went to bed, the battery reading was at about 48%. I didn't charge it, since there had been advice on this forum to wait until it was under 40% before charging. This morning, the battery was at 4%! (There had been a dramatic drop as well the night before, but I don't recall the figures.)

    I have no idea why this is happening. I haven't added any programs in the last few days, I haven't left the wi-fi on overnight. According to the battery stats this morning, the biggest user of the battery is Google Play Books, which surprises me. Yes, I've been reading a book on Google Play Books, but I wouldn't have thought that it would drain so much battery--it hasn't done so in the past. Also, I certainly didn't read the book in my sleep, so why should the battery have dropped from 48% to 4% overnight? (Hmmm...I see that Google Play Books was one of several apps that updated recently--possibly it did so on June 2, which might point to a disastrous update, but I'm not sure.) There are several apps asking to be updated--one of these updates might be to correct a bad recent update, I have no idea.

    Anyway, I'm including a screenshot of the battery usage and am hoping some people more experienced with these matters than I am can help me identify the cause of this dramatic overnight battery drop and suggest how to stop it from continuing.

    Thanks in advance for your help.
    Attached Thumbnails Enormous Battery Drain Overnight-battery605.jpg  
    06-05-2014 09:11 AM
  2. Terrorizer's Avatar
    I know this is a stupid question, but I might as well ask just to make sure, I'm assuming your display is set to go to sleep after a few minutes of inactivity, correct? I've known people that have set their screen to never sleep.

    Edit: nevermind, I looked at the screen useage percentage, its definitely not the culprit, haha.
    06-05-2014 09:14 AM
  3. cybernutte's Avatar
    Thanks, Terrorizer, for your quick response. It isn't a stupid question, but, as you've seen, the screen doesn't account for a lot of the usage, at least not now. It did figure in a more major way in the recent past, but I think not out of the normal range. Anyway, I have a Moko case that shuts things off when the case is closed, and as far as I can tell, it works.
    06-05-2014 09:56 AM
  4. GSDer's Avatar
    Was Google Play Books at the top of the list before you went to bed?
    Was it also the culprit the previous time?
    Have you rebooted the tablet since the problem began? Or since the update of the Google Play Books app?

    Any time you'd like an analysis of battery life you should post at least three screenshots - the overview (the one you posted), the History details (reached by pressing the graph at the top) and the Screen On details. If there's a particular app that seems to be at fault you should also include the screenshot of the details for that.

    You could try rebooting into Recovery mode and wiping the system cache.

    Sent from my rooted, debloated, deodexed Sinclair ZX-80 running CM -0.001 using Tapatalk
    06-05-2014 12:22 PM
  5. cybernutte's Avatar
    Thanks very much, GSDer, for your informative reply. In answer to your questions, I don't know whether Google Play Books was at the top of the list before I went to bed last night. I didn't look at the detailed battery listing, just the overall percentage of battery left. It was at about 48%.
    I think but am not 100% sure that Google Play Books was the culprit when the battery usage dropped overnight the night before, too.
    No, I have not rebooted since the problem began. I think that the problem began at approximately the same time as the Google Play Books update, though I can't be sure. All I know is that the date of the update on the Google Play Store site is June 2, and my dramatic declines in battery occurred overnight on June 3/4 and June 4/5.

    Thanks for the information about the sorts of screenshots I should provide. Since I've charged the battery, I can no longer get the info about what was happening before I charged it. But I'll definitely keep your info in mind for the future.

    What will be accomplished by wiping the system cache? I've never rebooted into Recovery mode, and I confess that not only do I not know how to do that (though I'm sure I can find the info online), I also don't know what else if anything will be affected by my doing this. Is there a way to wipe the system cache without going into Recovery mode?

    Again, many thanks for your help.
    06-05-2014 03:26 PM
  6. GSDer's Avatar
    [GUIDE] Nexus 7 (2012 & 2013) Cache Partition Wipe

    Wiping the system cache (unlike the individual application caches) can only be done in Recovery mode. It cleans out any cached files that the OS is using, which may include temporary files, old files from previous versions of apps, etc. It doesn't touch any of your data.

    Sent from my rooted, debloated, deodexed Sinclair ZX-80 running CM -0.001 using Tapatalk
    06-05-2014 04:12 PM
  7. cybernutte's Avatar
    Many thanks again, GSDer. I think I'll hold off on wiping the system cache until I see whether Google Play Books continues to be the likely culprit. If it is, I think I'd like to restore it to an earlier version. As far as I know, I can only do that by choosing Uninstall Updates from Apps-->Google Play Books. So I don't want to wipe out previous versions of this app quite yet.
    Again, thanks very much for all your helpful information. I greatly appreciate it.
    06-05-2014 05:15 PM
  8. B. Diddy's Avatar
    I see this behavior from time to time from various Google apps. I've seen it with Play Books, Newsstand, and Google+, among others. Usually, either a Force Stop or a reboot clear the problem. Hard to know why it happens.
    06-05-2014 05:24 PM
  9. cybernutte's Avatar
    Thanks very much, B. Diddy, for this additional information. I'm glad to know that I'm not the only one who has seen this behavior with Play Books, and it's interesting to know that other Google apps have at times also behaved this way. Thanks, too, for your suggestions about ways to deal with this when it happens.
    B. Diddy likes this.
    06-05-2014 08:15 PM

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