Galaxy S8 battery issues: rapid battery drain, turns off when unplugged from charger, won’t stay on

Although no longer considered the most powerful Samsung Galaxy S device out there, #GalaxyS8 is still pretty much an amazingly powerful phone. But just like any other top-of-the-line phone models in the market today, some devices will eventually succumb to premature battery issues. Today’s troubleshooting will give two cases where this problem can occur. And as usual, we also provide the steps on how to fix them so we hope that you’ll find this post useful.

Problem #1: How to fix rapid battery drain issue on your Galaxy S8

As of last Thursday, 4 May 2018, I observed the battery on my S8 Galaxy was unusually low (ie. 13% and falling at 4pm) when at this time would easily be at +50%. I checked the usual culprits (apps that may be running etc) and have not installed new apps.   The last system update was on 20 March 2018. So 3 days later .. this heavy and rapid drain without any other behavioural changes by the user is inexplicable. Unless .. is coded into the update [grrr!] to force users to consider replacing perfectly good phones. I have checked all your recommended steps.   Solution #1: Clear S8 system cache (done today, 7 May) Solution #2: Lower screen brightness (no change – default has always been low) Solution #3: Uninstall apps that run constantly in the background (only FB Messenger now; used to see What’s App but now doesn’t even show as option) Solution #4: Change screen resolution (FHD 1920×1080; and default on Power Saving mode) Solution #5: Turn off unused network services (no change) Solution #6: Don’t use Always On Display (is not used; also checked “Wallpaper and Themes” but now I have to agree to the terms and conditions of “themes” ? sheesh) Solution #7: Get rid of Assistants (never used – never activated so no change) Solution #8: Stop using your phone! (I don’t fiddle .. is used to navigate with Google Maps and take calls – regular, What’s App and FB Messenger) Solution #9: Use Power Saving Mode (always!) Solution #10: Keep the screen off (yup… when not in use.. always) Solution #11: Factory reset your S8 (doesn’t seem like this solution is connected to the cause.. just a whole lot of additional trouble). — Zmaltar

Solution: Hi Zmaltar. In many cases, fast battery loss issue is caused by usage habits more than by technical problems. If you haven’t installed a new app recently that might potentially cause battery to empty out prematurely, or if you’ve taken all the steps we suggest on how to use your phone smartly, then you can assume there’s probably a software bug that’s behind it. We want to emphasize on the word “probably” here since there’s no definitive way to actually check if this is the case. In best case scenario, we’ll only know it after doing some troubleshooting.

If you think doing a factory reset right away is way too drastic at this time, you can try two other possible solutions — battery and Android calibration and Reset All Settings. If nothing works after doing both, you should factory reset the device.

Battery and Android calibration

Sometimes, Android may lose track of true battery levels which can eventually lead to perceived fast battery drain issue. This can happen from time to time but it’s not a sole cause of the issue you’re trying to fix right now. There are so many other factors that can directly or indirectly lead to fast battery drain issue so recalibration of the battery and the OS is just one way of trying to address one aspect. This procedure is recommended to be performed at least once a month. If you haven’t tried it yet, follow these steps:

  1. Drain the battery completely. This means using your device until it powers down by its own and the battery level reads 0%.
  2. Charge the phone until it reaches 100%. Be sure to use original charging equipment for your device and let it charge up completely. Do not unplug your device for at least two more hours and also don’t use it while charging.
  3. After the elapsed time, unplug your device.
  4. Restart your S8.
  5. Use your phone until it completely runs out of power again.
  6. Repeat steps 1-5.

Reset all settings

When you reset all software settings, you’re basically doing a factory reset without the hassle of erasing personal data, and apps. When you do this type of reset, all settings except security, language, and account settings will be restored to their defaults. If there’s a software bug that causes the battery to drain faster than expected, this procedure may fix it. Here’s how to do it:

  1. Open Settings app.
  2. Tap General management.
  3. Tap Reset.
  4. Tap Reset settings.
  5. Tap RESET SETTINGS button.
  6. Restart your S8 and check for the problem.


Read: Galaxy S8 battery drains quicker after an update [troubleshooting guide]


Problem #2: Galaxy S8 turns off when unplugged from charger, won’t stay on, charges erratically

So, about a couple of hours ago, my phone abruptly switched off in my hand. I tried switching it on but it didn’t switch on unless I long pressed the power button. It had about 50% battery left when it switched off, and when I turned it on, the battery was 31%. The same happened for about 5-6 times and every time I switched the phone on, the battery was higher than before. After 6 attempts, it stopped turning on. I plugged it into my laptop, and its charging. If I unplug it, it switched off. Now, it shows battery in the following manner while charging: 85%, 86%, 100%, 85%, 86%. 87%, 88%, 100%, 88%, 89%. Now, whenever I unplug it, it switches off. What should be the possible issue and how can I help it? — Ruhi Kaushal

Solution: Hi Ruhi. We don’t know the history of your device in order to pinpoint the reason for your problem but there’s high probability that it can be due to a bad battery. The description of your problem is consistent to a malfunctioning battery. There are many reasons why this can be happening but generally, you can group them into two — software and hardware.

To know if you have a software issue at hand, we suggest that you do a battery and OS calibration as detailed above. If that won’t fix the problem, you can then try to clear the cache partition. Sometimes, bugs can occur if the system cache is outdated or corrupted. To ensure that that’s the case here, you can clear the cache partition and see what happens. Here’s how:

  1. Turn off the device.
  2. Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
  3. When the green Android logo displays, release all keys (‘Installing system update’ will show for about 30 – 60 seconds before showing the Android system recovery menu options).
  4. Press the Volume down key several times to highlight ‘wipe cache partition’.
  5. Press Power button to select.
  6. Press the Volume down key until ‘yes’ is highlighted and press the Power button.
  7. When the wipe cache partition is complete, “Reboot system now” is highlighted.
  8. Press the Power key to restart the device.
  9. Check for the problem.

Check for rogue apps

Incompatible or poorly coded apps can also mean problems for some unlucky devices. If you have plenty of installed apps and you don’t usually bother checking if they’re from reputable publishers, we suggest that you run your S8 to safe mode. As long as you install third party apps, you can never totally eliminate the possibility of a bug being caused by an app. To see if you’ve added an app that causes this problem, you need to boot your S8 to safe mode. Here’s how:

  1. Turn the device off.
  2. Press and hold the Power key past the model name screen.
  3. When “SAMSUNG” appears on the screen, release the Power key.
  4. Immediately after releasing the Power key, press and hold the Volume down key.
  5. Continue to hold the Volume down key until the device finishes restarting.
  6. Safe mode will display in the bottom left corner of the screen.
  7. Release the Volume down key when you see Safe Mode.
  8. Check for the problem.

Wipe your phone via factory reset

A more drastic solution that you can try in this case is factory reset. This will restore all software settings back to their defaults.

To factory reset your S8, follow these steps:

  1. Create a backup of your personal data.
  2. Turn off the device.
  3. Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
  4. When the green Android logo displays, release all keys (‘Installing system update’ will show for about 30 – 60 seconds before showing the Android system recovery menu options).
  5. Press the Volume down key several times to highlight ‘wipe data / factory reset’.
  6. Press Power button to select.
  7. Press the Volume down key until ‘Yes — delete all user data’ is highlighted.
  8. Press Power button to select and start the master reset.
  9. When the master reset is complete, ‘Reboot system now’ is highlighted.
  10. Press the Power key to restart the device.

Flash stock firmware to your S8

If your S8 started behaving erratically after installing the latest available Android update and it’s the only different thing that you did that might have caused the problem, you can try to downgrade Android via flashing. As a warning, keep in mind that flashing can seriously cause serious software issues when not done properly. This possible solution is only recommended for advanced Android users. If you haven’t heard of the terminology, or if you’re not confident that you can do it, don’t bother with it at all.

Flashing stock firmware to a problematic device after an update is often an effective choice for seasoned Android users. It’s really not rocket science and as long as you follow a good guide, you should be good. If you want to give it a try, visit web sites like XDA-Developers Forum and search for threads that will show you how to do it.

Before flashing, make sure that you create a backup of your personal data and take note of the software version of your phone under Settings > About phone > Software info. Flashing guides can vary slightly on some models so be very careful in picking the right guide for your particular phone model.

Contact Samsung

The safest alternative that you can do though is be letting Samsung know of your issue by bringing the phone to their Service Center. You need to do this if nothing changes after you factory reset your S8. There’s a big chance the phone’s battery may be problematic and a replacement may be needed to fix it.


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