Why Xiaomi Mi 8 owners want to turn off fast charging?
Xiaomi Mi 8, released in 2018, was one of the first flagships of the brand to support Quick Charge 4+ technology. Back then it was an innovation: 18-watt charging allowed you to restore 50% of the battery in 30 minutes. But after 5-6 years, many users face a problem: the battery holds a charge for only a few hours, and the phone overheats even at minimal load.
The reason is often the degradation of lithium-ion batteries. Rapid charging speeds up this process, as high current and temperature reduce the life of the batteries. According to research, a battery that constantly charges at high power loses up to 30% of capacity after 2 years of active use. Shutting down fast charging can extend the battery life by 1-1.5 years – especially for the Mi 8, whose original batteries have long been out of production.
There are other reasons to stop using Quick Charge:
Overheating of the body during charging (especially in summer or during games).
Unstable operation when using non-original chargers.
The desire to use a smartphone as a powerbank – slow charging spares ports and cables.
But before you change the settings, it's important to understand that turning off fast charging won't bring back the capacity of the lost battery, it will only slow down its further degradation. If your Mi 8 runs out in 2-3 hours, it might be time to consider replacing the battery.
Method 1: Disconnect via standard MIUI settings
The easiest and safest method is to use built-in system options, which is suitable for most versions of MIUI 10-14 (including global and Chinese firmware), the main advantage is that it does not require superuser rights (root) and does not affect the warranty.
Step instructions:
- Open the Settings app (the gear icon on the home screen).
- Go to the Battery and Performance section.
- Select Charging (in some versions of MIUI it may be called Charging Settings).
- Find the option Quick Charge (or Quick Charge) and move the slider to the off position.
- Confirm the action if the system requests additional confirmation.
If you don't have Fast Charging on the menu, your version of MIUI is hiding it, and one of the alternative ways that we've described below will help.
Use the original Xiaomi power supply
Charging cable intact
The phone is not connected to a PC or other device
Battery level: 20-80% (optimum for changes)-->
What will change after the shutdown:
- ⚡ The full charge time will increase with ~1.5 hours to 3-4 hours (depending on the power supply).
- 🌡️ The temperature of the body during charging will decrease by 5-10°C.
- 🔋 Battery degradation rate slows by 15-25% (GSMArena test data).
- ⚠️ Some wireless charging systems may stop working (if they only support fast protocols).
Method 2: Use the engineering menu (#4636##)
If the standard settings do not allow you to disable Quick Charge, you can use the hidden engineering menu, which works on most firmware, but requires caution - wrong actions can disrupt the stability of the system.
Step-by-step:
- Open the phone app and enter the combination: ##4636##
- In the menu that appears, select Battery Information.
- Scroll down to the Charging section.
- Find the AC charge limit or Fast charge config and set the Disabled value.
- Save the changes and restart the phone.
⚠️ Note: On some versions MIUI The engineering menu may be missing or blocked. If nothing happens after you enter the code, your firmware doesn't support this method.
What to do if the engineering menu is not opened?
Advantages of the method:
- 🔧 It works even if the standard settings are hidden.
- 📱 No need to root.
- ⚙️ Allows finely adjusting charging parameters (for example, limiting current).
Disadvantages:
- ❌ On the new versions MIUI may be blocked.
- ⚠️ Misguided changes can lead to unstable work.
- 🔄 After resetting the settings will have to repeat the procedure.
Method 3: Disconnect via ADB (for advanced users)
If the first two methods fail, the Android Debug Bridge (ADB) option remains, a versatile tool for deep customization of Android devices, but it requires preparation.
What you need:
- 🖥️ Computer with Windows/Linux/macOS.
- 🔌 USB-cable (preferably original).
- 📥 Installed Xiaomi drivers ADB/Fastboot Tools.
- 🔐 Included debugging by USB phone-on.
Instructions:
- Activate Developer Mode on Xiaomi Mi 8: - Go to Settings → About Phone. - 7 times click on the MIUI version until the notification You became a developer!.
- Return to Settings → Additional → For developers and enable USB debugging.
- Connect the phone to the PC and confirm the debugging permission.
- Open the command line (Windows) or the terminal (Linux/macOS) Enter: adb shell settings put global fast_charge 0 Next: adb shell settings put global wireless_fast_charge 0 (The second command disables fast wireless charging if it is supported).
- Reset the device.
⚠️ Attention: Misuse of the right ADB If you are not sure about your actions, you should consult a specialist, also note that after resetting or updating your settings, you should also consider that if you are not sure about your actions. MIUI You have to repeat the procedure.
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Before using ADB, back up your data via Settings → System → Backup. This will take 5-10 minutes, but save your photos and contacts in case of a crash.
Table: Comparison of methods for shutting down fast charging
| Method | Difficulty | Need root? | Impact on the guarantee | Efficiency |
|---|---|---|---|---|
| Standard settings of MIUI | ⭐ (simple) | ❌ No. | ❌ No. | ✅ High (works in 80% of cases) |
| Engineering menu | ⭐⭐ (middle-of-the-road) | ❌ No. | ❌ No. | ✅ Medium (depending on firmware) |
| ADB-team | ⭐⭐⭐ (difficult) | ❌ No. | ⚠️ Possible if the system is broken) | ✅ High (works almost always) |
| Applications from Third Party Developers | ⭐⭐ (middle-of-the-road) | ✅ Yes, for most) | ✅ Yeah (removes warranty) | ⚠️ Low (risk of viruses) |
What to do if the fast charging does not turn off?
If none of the methods worked, the reasons may be as follows:
- Non-original firmware: Castom builds (like LineageOS or Pixel Experience) can ignore the fast charging settings. Solution: go back to the official MIUI.
- Hardware malfunction: If the charging controller is damaged, the phone can always use maximum current. Solution: diagnostics at the service center.
- Manufacturer-Blocked: On some versions of the Xiaomi Mi 8 (e.g., for the Chinese market), Quick Charge shutdown is locked at the kernel level.Solution: Fastboot flashing.
- Conflict with MIUI optimization: Smart charging (in battery settings) can automatically enable fast charging. Solution: disable all optimization options.
If you suspect a hardware problem, check for the following symptoms:
- 🔥 The phone warms up even when the fast charging is turned off.
- ⚡ Charging is jerky (current jumps from 0.1A to 2A).
- 🔋 The battery is swelling or deformed.
- 🛠️ The charger emits extraneous sounds (squeaking, crackling).
In such cases, disabling Quick Charge software will not help – repairs are required. The average cost of replacing the charging controller with the Xiaomi Mi 8 in 2026 is 1500-2500 rubles (depending on the region).
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If the phone stopped holding charge after the fast charge was turned off, it doesn't mean that the method didn't work, but the battery was probably already worn out and needs to be replaced.
Myths and truth about fast charging on Xiaomi Mi 8
There's a lot of rumors going around the Quick Charge technology.
Myth 1: “Switching off fast charging will completely stop battery degradation.”
Truth: Lithium-ion batteries degrade anyway, but slow charging slows down, and the right settings can extend battery life by 20 to 40 percent, but not make it eternal, according to a University of Michigan study.
Myth 2: “Fast charging only spoils non-original batteries.”
Truth: Even Xiaomi’s original battery (article MBJ405630) suffers from high currents, the only difference being that non-original cells can swell or ignite when overheated.
Myth 3: “If you turn off Quick Charge, your phone will only charge from USB 2.0.”
Truth: Charging speeds depend on the power supply, not the port. Even with fast charging turned off, the Mi 8 can receive up to 10 watts via USB-C if the charger supports the appropriate protocols.
Myth 4: “You can’t use wireless charging after you turn off Quick Charge.”
Truth: Wireless charging (if supported by your model) will work, but at standard power (5–7.5 W instead of 10–15 W).
⚠️ Warning: Don't believe the advice to "calibrate the battery" by completely discharging and charging. For today's lithium-ion batteries, this is harmful and can reduce their life. The optimal mode is to keep the charge in the range of 20-80%.