My phone is a Samsung Galaxy S5 mini, so it's getting old by industry standards. Until a few months ago, it was doing fine, but recently the battery life and response time have drastically degraded. Even with every optimisation I know of, I am now lucky if the battery lasts a day (~16h). 8h is more typical. The phone sometimes hangs for long enough for the screen lock to activate (2 minutes). When the hanging is particularly bad, I have noticed that the phone feels warm.

I have seen messages saying that two apps (Facebook messenger and DJI pilot) have caused ~17 errors each in the past week, so I should optimize power settings. Activating "save power" hasn't helped.

The standard battery indicator says that 20-25% is used by the screen , 15-20% by the Android System, and 10-15% by Android OS. I tried to get more information on the battery by installing "Repair Battery Life". This app claimed to repair 5 "low" cells. But it seemed far too easy. I'm sceptical whether an app can repair battery cells.

I can think of some things that have changed in the last few months, but I wouldn't expect them to have made such a big difference. I have installed some new apps, but none use more than 3% of battery. I assume this means that they're not consuming enough CPU to hang the phone either. One of the new apps is perhaps more of a suspect than the others: Netguard. I would expect that less network traffic would save battery, but I could be mistaken if apps are very aggressive about retrying the connection. Finally, I have moved house, and the reception (wifi & whatever you call the normal network) might be worse, but not noticeably.

What else can I try to get more information on the problem(s)?

Update: I noticed two new symptoms.

1) the phone only seems to hang when I am out of wifi range.

2) looking closer at the battery menu under Settings, there seems to be significant battery usage at times where the phone is "awake" but the screen is off. Does this mean that some app is constantly waking the CPU?

Update2: today I had the screen on for 2 hours straight, which took my battery from ~75% to 15%. Clearly, a lot of this was for the screen, so I was surprised to see that in the battery stats, it says that the screen used 15% of the battery, while "android system" used much more: 19% and 5 hours of CPU time. "Android OS" also has a significant contribution with 8%. Is there any way to narrow down why the Android components are so active?

  • 3
    Most apps that claim that they can regain your battery life do more harm than anything. Get rid of that "repair battery life" app. Then, get rid of facebook app / messenger to see how much battery you gain. If you want, you can visit facebook via chrome and save it on your homescreen as a chrome shortcut. FB on chrome supports push notification I've read. So you still would be updated on that front. As a baseline, remove all apps that you've not used in a couple of weeks or so. Then test to see if it makes a sizable difference.
    – blueren
    Aug 24, 2017 at 5:26
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    Push notifications via chrome is a good idea. I haven't had the main fb app for ages because it was a battery drain (and because the notifications were annoying). I will see how things go without FB messenger.
    – craq
    Aug 24, 2017 at 5:32
  • For further hints, our battery-life tag-wiki is a good starting point, too. You also can check my list of battery helpers to see if one of them can pin down the culprit (I personally often use BetterBatteryServer for that, but GSam should be a good choice as well).
    – Izzy
    Aug 24, 2017 at 6:17
  • How much time since the last cache and Dalvik wipe, OP?
    – Grimoire
    Aug 24, 2017 at 17:44
  • @DeathMaskSalesman I hadn't heard of dalvik before. It looks like I'd need to root my phone in order to clear that cache? Is the other cache you mention for each app individually? I haven't cleared that in a long time.
    – craq
    Aug 24, 2017 at 20:50

2 Answers 2


Educated guess is you have apps that are running in the background and eating up your battery. Samsung power manager app/thing is not great (at least on my sgs7 it isn't), but it's pointing you on possible culprits. Easiest way to debug is uninstall the apps and see if device acts any differently (give it a few days or a week to see). Or another way is factory reset start from new and see how it goes from "stock" and add apps slowly and see. Or it could just be the battery is aging and simply can't hold a charge like it used to. There isn't a silver bullet way of trouble shoot battery life unfortunately.

  • I've seen some nice tools that monitor battery health for electric vehicles, and hoped there might be something similar for phones. If not, then I'll have to assume the battery is OK (can't do much about it if it's not), and use trial & error to track down which app is at fault.
    – craq
    Aug 24, 2017 at 5:43
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    It turns out that as bad as the power manager app is, it seems to be the best available. I uninstalled the apps from facebook and DJI a week ago, and the problem seems to have gone away. If it returns, I'll report back.
    – craq
    Oct 3, 2017 at 5:20

Unlike the iPhone and Galaxy S6 and newer phones the S5 mini has a replaceable battery. Batteries get old. Get a new one. Not terribly expensive on Amazon. Personally the G5 was the last Samsung phone I owned. I wanted to go from a G4 to G6 except Samsung stopped the replaceable battery with the G6. G5 was OK for a year or two but then I wanted to upgrade so went to the LG V20. I do a lot of subway riding and watch movies so go through 2 batteries every day. I love the LG with it's fingerprint unlock too. I can only imagine Samsung followed the iPhone with non-replaceable batteries as a designed-obsolescence which I think is a dirty trick to play on consumers and a greedy business strategy.

  • It's not my downvote, but I imagine it's because most of the answer doesn't address the question. While the problem could be the battery, I'm starting to think that 1) the onset was too fast, and that battery degradation tends to happen slowly. 2) that wouldn't explain the performance issues. You did give me an idea though: I can try swapping the battery and see if the problem persists.
    – craq
    Sep 21, 2017 at 20:56
  • Correct. My experience with bad batteries is that they bulge out a little but it's not too noticeable until next to a new battery. Bad battery should be the fist thing to rule out fast discharge.
    – Jerry P.
    Sep 21, 2017 at 23:11

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