How to fix Galaxy S9 battery drain issue: discharges fast when it reaches 30%

Fixing battery drain is usually not a simple affair. There are a number of possible reasons for it so nailing down the real cause can be challenging. In this post, we show you what you can do if you have a battery drain issue on Galaxy S9 like the one below.

Problem: Galaxy S9 battery discharges fast when it reaches 30% (battery drain issue)

Hello My Samsung S9 is having battery issues. Sometimes i get to 30% battery and dont touch phone for 5 minutes to only discover phone battery has completely discharged and have to charge phone. This happens at different percentage of battery but all under 30%. When it does get to show battery needs charging at 15% warning, i put phone on charger only to watch it the phone discharge to 0% turn off and start charging. I do use the device manager to check battery and am now wondering if that has some effect on what is going on. Look forward to your suggestions. Thank you.

Solution: Any power or battery issue can have a number of causes. To know where the problem lies, follow the suggestions below.

Restart. Sometimes, this simple procedure can fix bugs that developed after the system has run for a long time. By manually forcing your Note8 to reboot, you’re basically simulating a battery pull, which, in older mobiles with removable battery packs, was an effective way to refresh the system. If you haven’t tried this one yet, here are the steps that you can do:

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

Clear the cache partition. If refreshing the system won’t change anything, the next good thing that you can do is to clear the cache partition. Android uses a system cache, which is stored in the cache partition, to load apps quickly. Sometimes, this cache gets corrupted during and after an update, or for some other reasons. While this may sound harmless, a corrupted cache can eventually cause performance issues as well as a bunch of other minor annoyances. To ensure that your phone’s system cache is fresh, you can wipe the cache partition. This will force the phone to delete the current cache and replace it with a new one over time.

To wipe the cache partition on your S9:

  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.

Use official charging cable and adapter. Many Android users often underestimate the importance of using official charging accessories. What many don’t realize is that charging cables and adapters can go bad just as easily as the main device itself. Make sure that you’re using the cable and adapter that came with the device to lessen the chances of charging problems. If you think that the cable is bad, try to replace with another official cable. Keep in mind that the standard USB cable has tiny wires inside that can easily break. If there are too many broken wires inside, your phone may not receive enough power when charging. This can cause battery problems, damage the phone, or cause slow charging.

Battery calibration. Your device may need a battery calibration. Sometimes, the software can get conflicting information from the battery resulting to incorrect power level readings. To see if that’s the case, you want to do a battery calibration. Here’s how:

  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. Perform a warm restart by holding the Power and Home buttons simultaneously until the startup logo appears.
  5. Use your phone until it completely runs out of power again.
  6. Repeat steps 1-5.

Run the device on Safe Mode. At times, a third party app may cause the phone to become buggy. This can be due to incompatibility issues with the app, or some coding changes after an update. To check if one of the apps is interfering with Android, you can run the device to safe mode. On Safe Mode, all third party apps will be blocked, allowing only preinstalled apps to run. This means that if there’s no power or battery issue on safe mode, one of the apps is behind it.

To boot your S9 Plus to safe mode:

  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.

To identify which of your apps is causing the trouble, you should boot the phone back to safe mode and follow these steps:

  1. Boot to safe mode.
  2. Check for the problem.
  3. Once you’ve confirmed that a third party app is to blame, you can start uninstalling apps individually. We suggest that you begin with the most recent ones you added.
  4. After you uninstall an app, restart the phone to normal mode and check for the problem.
  5. If your S9 is still problematic, repeat steps 1-4.

Reset app preferences. In some cases, apps may encounter problems if one or a number of default or core system apps and services are disabled. To ensure that all your apps have access to defaults apps, do the steps below:

  1. Open Settings app.
  2. Tap Apps.
  3. Tap on More settings at the upper right (three-dot icon).
  4. Select Reset app preferences.
  5. Restart your S9 and check for the problem.

Factory reset. You should consider wiping the device if none of the things mentioned above has improved the situation. If there’s a software bug that causes the problem, factory reset will most likely address it. Don’t forget to back your files up before wiping the phone. To factory reset your S9:

  1. Create a backup of your 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.


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