How to fix a Galaxy S9 with battery drain issue after installing Android Oreo update

We’ve received reports from some #GalaxyS9 owners that the battery of their devices seemed to have drained faster after installing an update for Android Oreo. We know that the S9 comes pre-installed with Android Oreo so these updates must be carrier-specific updates or minor patches for Oreo released by Samsung or Google. Regardless of what updates you install though, the general solutions for this type of issue does not vary much. If you think your S9 has been draining battery power faster after updating Android Oreo, then this post is for you.

Force restart

Before doing advanced or even drastic solution options, we suggest that you start with the more simple ways to address bugs. In your case, the problem is most likely operating system so there’s a chance that a quick reboot may fix it. Whether you experience issues or not, it’s good if you make it a habit of regularly restarting your device. Not only does it fix issues; in majority of cases, it also prevents new ones from developing as well as refreshing the operating system so it performs faster. It’s simple to perform and can potentially fix issues so why not try it.

While you can definitely restart your device normally by pressing the Power button and selecting restart from the menu, we suggest that you try a battery pull instead. This is done by following these steps:

  1. Press and hold the Power + Volume Down buttons for approximately 10 seconds or until the device power cycles. Note: Allow several seconds for the Maintenance Boot Mode screen to appear.
  2. From the Maintenance Boot Mode screen, select Normal Boot. Note: Utilize the volume buttons to cycle through the available options and the lower left button (below the volume buttons) to select. Also, allow up to 90 seconds for the reset to complete.

Solution #1: Cache partition wipe

Many issues following an update are caused by a corrupted system cache so it only follows that the first solution option to try is to deal with it. Android uses a cache to load apps quickly. This cache is stored in a special partition in the storage device called cache partition. Mainly, this cache keeps previously opened pages and files for apps. By keeping these files, Android will have a faster way to loading apps because it no longer needs to load them from the internet or search from other locations. At times though, this cache gets corrupted or may become outdated. In your case, the cache may probably have gotten corrupted after installing an improvement for Android Oreo. To ensure that your S9’s system cache is refreshed, follow these steps:


  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 Android logo displays, release all three keys.
  4. An ‘Installing system update’ message will show for 30 – 60 seconds before the Android system recovery menu options appear.
  5. Press the Volume down key several times to highlight wipe cache partition.
  6. Press Power key to select.
  7. Press the Volume down key to highlight yes, them and press the Power key to select.
  8. When the wipe cache partition is complete, Reboot system now is highlighted.
  9. Press the Power key to restart the device.

Solution #2: Minimize screen brightness

One of the main reasons why battery may appear to drain faster than normal, whether or not you just installed an update, is the screen. Yes, your S9’s bright, colorful, and fantastic screen may be nice to behold but it comes at a steep price — by draining the battery rapidly. If you are serious in preventing massive battery drain everyday, make sure to lower the brightness of your screen, especially if you use your phone indoors most of the time. Try to lower the screen to lowest tolerable level for you and stick with it.

Solution #3: Install app updates

Like Android operating system, apps also run on imperfect codes so they need improvements and fixes from time to time. With the advent of new Android versions, some apps may quickly become problematic. Sometimes, apps even become totally incompatible so as to interfere with the operating system’s functions. The way to minimize incompatibility problems is to ensure that you also install the latest available updates for them after installing operating system or carrier updates. While this may not be a problem if you set Google Play Store app to automatically update them for you, others may not be so if they set Play Store to not inform them of new updates. If you’re one of them, be sure to check Play Store app settings for updates to your apps.

Solution #4: Check for apps that run in the background

Some apps are designed to constantly run in the background. If you installed plenty of such apps, chances are they’re the main factor why your battery appears to drain faster than normal. Fortunately, you don’t need to install another app to check. Android Oreo has a built-in tool to help you do just that. To access this tool, follow the following steps:

  1. Open Settings app.
  2. Tap Device maintenance.
  3. Tap Battery.
  4. Tap BATTERY USAGE.
  5. Check for apps that you don’t normally use that long but remains high on the list. Apps that always run in the background tend to consume a lot of battery power day in and day out.

Some bad or malicious apps also tend to regularly run in the background as they usually send and receive instructions and updates from their server. If you find an app or service that consumes a lot of power, try to uninstall it and see if there’s a difference in battery performance.

Solution #5: Change screen resolution

Your Galaxy S9’s screen resolution can be changed. You can do that under Settings. There are three options that you can choose from so we recommend that you use the lower resolution option. Unless you use your S9 to view high resolution images and videos all the time, there’s really no point in using the highest resolution for such a relatively small screen. When it comes to bigger screens, like a living room TV set or computer monitor, yes using high resolution may matter. Not in your S9’s screen though. The thing is, the higher the resolution you use, the harder your device’s computer to work when rendering images and videos. This means that the processor and graphics chip will have to consume more power in order to show you an image or video. If you want to change the resolution of your S9 screen, just go to Settings > Display > Screen resolution.

Solution #6: Disable unnecessary features and functions

Samsung has packed their latest Galaxy model with a lot of unnecessary features. Most of them won’t affect your experience of the device at all so they are generally useless to many people. However, leaving them turned on can drastically affect the performance of the battery.  For example, enabling Nearby device scanning allows the Bluetooth function of your device to regularly scan for other Bluetooth devices even if the main Bluetooth switch has been turned off. While the power consumption for this under-the-hood functionality is miniscule, it can accumulate pretty fast if other features are turned on throughout the day.

We suggest that you invest some time checking all the features under Settings app and to disable those that you don’t need.

Also, try to turn off commonly used networking features like wifi, mobile data, and Bluetooth when you’re not using them. When you’re in an area with poor network coverage, consider enabling Airplane Mode to prevent your phone’s radio to regularly scan the airwaves for a signal. This constant scanning can cost big amount of battery power if left for a long time.

Solution #7: Turn off Always On Display (AOD)

While Always On Display (AOD) has its place in your S8, it can contribute to fast battery drain issue throughout the day. If you think you’ll be unable to recharge your S8 soon, turning off AOD may be wise.

Solution #8: Turn off Assistants

Like its predecessor, the Galaxy S9 has two competing virtual assistants that you can use — Bixby and Google Assistant. While any of them has certainly their uses for individual S9 owners, a lot of people generally forget about them, or don’t use them at all. The thing is, Bixby or Google Assistant consumes battery power even if you’re not using them as they are constantly on alert for your command. If you don’t rely on them too much, we recommend that simply turn them off.

Solution #9: Use Power Saving Mode

This is technically not a solution but a remedy to slow down battery consumption. Still we feel that it’s important that we mention this feature in case you badly need to extend the battery for any given day. Power Saving Mode feature works by slowing down your phone’s computer in order to lower its battery consumption. This is a handy but drastic option if you want to your S9’s battery to go as long as it can before the battery is emptied.

To access Power Saving Mode, just go to Settings > Device maintenance > Battery.

Solution #10: Factory reset

Finally, if all our suggestions above won’t work, you should try to factory reset the device. This procedure aims:

  • to know if the problem is software-related, and
  • if you can fix battery drain by reverting all software settings back to their defaults.

While only a very small number of Galaxy S9 has battery issues after installing a minor update for Android Oreo, we can’t totally eliminate the chance of it happening on your device. By doing a factory reset, you may be eliminating a software bug that causes the battery to drain abnormally fast.

To factory reset your S9:

  1. Back up data on the internal memory. If you have signed into a Google account on the device, you have activated Anti-theft and will need your Google credentials to finish the Master reset.
  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 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.