Galaxy S9 won’t fast charge, Adaptive Fast charging stopped working [troubleshooting guide]

The #GalaxyS9 is basically just an improved Galaxy S8 and the same is true for one of its crucial draws — fast charging capability. With the S9, fast cable charging is barely able to get a little faster over the S8’s performance so there’s not much to be excited about it. Given that both devices have the same exact battery capacity of  3,500mAh, we think that that only reason why the S9 has a slight edge when it comes to its fast charging performance over the S8 is due to its more efficient chipset. It’s not much though and an average user won’t be able to tell the difference at all. Sad but true.

Anyways, S9 s never really different than that of its predecessor so it’s not surprising that it suffers the same exact problem — unreliable fast charging functionality. In this troubleshooting article, we’ll discuss what you need to do when you realize that your new S9 no longer charges fast as you expect it to be

Fix #1: Verify fast charging is enabled

S9 fast charging is enabled by default. We can’t see a good reason why a user might switch to slower charging (which can take several hours at a stretch) but if ever you want to double check it, here’s how:

  1. Open Settings app.
  2. Tap Device maintenance.
  3. Tap Battery.
  4. Tap More options at the upper right (three-dot icon).
  5. Tap Advanced settings.
  6. To turn on Fast cable charging, touch the slider.

While you’re at it, make sure that fast wireless charging is also enabled, in case you’ll want to charge wirelessly in the future.

Fix #2: Charging works faster when phone and/or screen is OFF

Our charging test showed that an S9 charges slower when you’re using it. That’s mainly because its huge screen consumes a lot of power, even when set to its dimmest possible level. When left alone and off, a fully drained S9 battery can reach 20% charge in only 20 minutes so if you’re using the phone while charging, the longer the charging time takes. It can also significantly reduce the effect of Adaptive Fast charging.

Our recommendation is to plan your charging sessions smartly. For example, you might want to charge your device during times when you’re busy at work or at home. Using your phone while charging is never a good idea, even with older devices so if you’re after charging efficiency, use smarts and avoid the temptation of tinkering with your device. Better still, let the phone rest for a couple of hours by turning it off while charging. That will not only help extend the overall battery life in the long run but it can also help you discipline yourself. This surely won’t sit well with some, but if you really don’t expect a call for the next few hours, just powered down the device while charging.

Fix #3: Use Samsung-provided charging cable and adapter

Your S9’s Adaptive Fast charging feature was designed to work with accessories that Samsung built so it’s really a no-brainer to use non-Samsung cables and adapter, especially if you’re having charging troubles. While there are tons of third party accessories out there that you can use with your S9, we strongly recommend that you stick with the stock ones from Samsung. They’ve been validated to work with your device and their parameters have been taken into consideration to maximize the effect of Adaptive Fast charging feature. Using a non-Samsung USB cable may not allow the same current and voltage to go to the system, potentially slowing fast charging. To put it simply: Use Samsung USB cable and adapter. Period.

Fix #4: Restart your S9 to Safe Mode and observe

Many issues in Android devices are caused by apps or their interference with the operating system. If your S9 seemed to have suffered slow charging performance after installing apps, that can be a telltale sign that one of them is problematic or incompatible. As fast charging feature is managed by Android, one of your apps is probably messing up the power management functionality of your device. To check, you want to bring your device to safe mode. While your S9 is in safe mode, all third party apps and services won’t run. So, if the device charges normally (Adaptive Fast charging is working), you can assume one of your apps must be preventing Adaptive Fast charging to not work properly. In this case, the only permanent fix is to identify that app and delete it from the system.

In order to load your S9 to safe mode, follow these steps:

  1. Turn the device off.
  2. Press and hold the Power key past the model name screen appearing on the 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. When Safe mode appears in the bottom left corner of the screen, release the Volume down key.

Fix #5: Uninstall apps

If you think that an app is the reason why fast charging has stopped working on your S9, your next move is to determine what that app is. It’s really simple to do that but it may take some patience and effort to see through it. This is especially true if you have hundreds of installed apps. We suggest that you start with most recently installed apps, then progress to the last one.

Basically, what you want to do is this: uninstall — observe — uninstall — observe. This is the cycle that you must do to identify the culprit. After you removed an app, be sure to let your S9 charge for a few minutes so you’ll know if fast charging has resumed.

Fix #6: Install Android updates

Whether you have an issue or not, it’s always good to install app and Android updates whenever they become available. We’re not aware of an S9 fast charging issue that can be fixed by a new Android update but still, it’s ideal if your phone’s software environment is up-to-date.

Fix #7: Keep charging port dry

Like its predecessors, the S7 and S8, your S9’s charging port may not work properly if it’s wet or has detectable moisture. Be sure to air dry the phone properly after using it near water, or after using it near a wet environment. avoid applying direct heat to the port such as blowing hot air as that might compromise the seals around the port. Water usually evaporates on its own after some time so make sure to shake your phone vigorously, wipe it with a clean, soft cloth, and let nature takes care of the rest.

You’ll know if the system perceives moisture because the moisture detected error will show. Still, no system is perfect so there’s always a chance that your S9 may fail to alert you of liquid in the port that may be causing a charging problem.

Fix #8: Wipe the phone thru factory reset

Factory reset aims to resolve any software-related issue on your S9. You only want to do this if all our suggestions above don’t work at all. Here’s how:

  1. Back up data on the internal memory. If you have signed into a Samsung account on the device, you have activated Anti-theft and will need your Samsung 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 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.

Fix #9: Contact Samsung support

Remember, fast charging failure can also be caused by bad hardware. If nothing changes after you’ve exhausted all software solutions, you have to send the phone in. Samsung either needs to have the phone repaired or replaced, depending on which one is economically viable for them.

Fix #10: Use wireless charger

Should yo want to keep your S9 for some time before sending it in, a good workaround would be to use fast wireless charging. Although it’s not as fast as fast cable charging, it’s a good alternative than the slower cable charging you may have. Wireless cable charging has its own use but it’s certainly not a permanent fix your problem.

Be aware that fast wireless charging produces more heat than fast cable charging so it can shorten battery life faster than  traditional cable charging. If you want to keep your S9 for at least a couple of years, we suggest that you get fast cable charging fixed for good.

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