1. bocaboca's Avatar
    Hi all!

    I read all the related topic on this and other forums before posting here. However, I couldn't find a satisfying answer until now.

    I have a Samsung Galaxy S4 for 15 months. Recently I realized that the phone randomly reboots at night. I noticed that because it asks me again for pin code in the morning, and also sometimes I hear it rebooting because I have a very light sleep .

    Related answers comment about the battery, temperature due to heavy usage, pressure, faulty apps, accidentally pressed buttons.

    1. I care very much what I install.
    2. My problems happen at night, when phone should be idle, out of anybody's reach. This rules out all of the aforementioned reasons, and really makes me clueless.

    Is it possible that it installs some updates during the night and does a manual reboot? I have the mobile data active all times, so the phone can access the internet by itself to do "wanders" at night . This morning I wiped the cache partition, not sure if it will help.

    Can anybody provide any comment about why this may be happening, and maybe give me some advices?

    Thanks in advance and kind regards!
    10-30-2014 11:25 AM
  2. B. Diddy's Avatar
    Welcome to Android Central! So you normally don't have to enter a PIN when you unlock the phone--only when it reboots?

    It doesn't necessarily matter if you're very careful with the apps you install--it can be difficult to predict when an app or a combination of apps might cause a conflict and force a reboot. Try booting into Safe Mode, and see if the random reboots persist. Slowly reactivate apps one by one, and see if and when the reboots recur. This can be a tedious process, but sometimes it's what's necessary to troubleshoot. Restart the Device in Safe Mode - Samsung Galaxy S® 4
    10-30-2014 11:36 AM
  3. bocaboca's Avatar
    Welcome to Android Central! So you normally don't have to enter a PIN when you unlock the phone--only when it reboots?
    Thanks for the quick reply. I enter PIN only when I turn on or reboot my phone. For unlocking, I do with a simple finger movement (factory settings). So when I see it stuck at the PIN code entering screen in the morning, I am sure it rebooted already.

    Judging by your answer, I guess you suspect about some faulty application. I will try that eliminating process (safe mode + adding apps) until I encounter the one causing the problem. Let's see what will happen
    10-30-2014 11:46 AM
  4. B. Diddy's Avatar
    Another question--do you keep the phone plugged in overnight? If not, do you ever see excessive battery drain by the morning?
    10-30-2014 11:56 AM
  5. bocaboca's Avatar
    Another question--do you keep the phone plugged in overnight? If not, do you ever see excessive battery drain by the morning?
    No, I charge it only during the day for 1.5 - 2 hours (as much as it needs to fully charge from 1-10% when I plug it in).

    Regarding the battery drain, I did see something strange. First when I checked in the morning the battery status, it's like 5-6 hours disappeared from the statistics, because it says working for 1d 5h, while it was on already 1d 11h (my recollection of the last charging). So it discarded these 5-6 hours from the battery statistics, which I find strange, but maybe that's how it works(?). And consequently in the battery statistics it has an instant drop of 3-4% for these "lost" hours.

    Until now I didn't pay much attention to these things, but now that I am sure I have a problem, I will pay much more attention to these details.
    10-30-2014 12:04 PM
  6. Rukbat's Avatar
    15 months of discharging the battery down to 10% probably means that the battery is about ready for replacement, and is probably shorting internally for a moment, forcing a reboot. You should normally recharge a lithium battery at about the 40%-60% point. (See Battery University - How to Prolong Lithium-based Batteries You can use the second chart to do your own math, but that's the way to keep the battery lasting the longest. Rechargng at 10% gives you about 300 recharges, and you've probably exceeded that already.)

    Discharging it down to 1% is a sure way to kill it fast. I've seen batteries treated like that last about 6 months.

    It may not be what you want from the battery, but lithium is the lightest metal, so a lithium battery gives us the highest power to weight ratio, even it it has some problems that haven't been solved yet. A lead gel cell would be able to take that punishment, but one with enough power for a phone would be about as large as about 3 Note 2s one on top of the other and weigh about 5 pounds. You wouldn't want to walk around with that in your pocket.
    B. Diddy and bocaboca like this.
    10-30-2014 04:12 PM
  7. bocaboca's Avatar
    Wow, thanks, this is totally new for me! I am an "old school guy", I charge until 100%, drain until 1-5%, and then recharge. In the beginning I was even letting it die, and then charging fully while it is turned off. Old habits die hard. But seems that is a counter-productive way for the new batteries... hmm ... looks like I have a lot to read
    B. Diddy likes this.
    10-31-2014 08:01 AM

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