Xiaomi Mi 9 is the flagship smartphone of 2019, which still remains relevant due to the powerful hardware and support for modern features. One of the key features of the model is the fast charging Quick Charge 4+ (27 watts), allowing you to recover 70% of the battery in just 30 minutes. However, many users are faced with the fact that the smartphone charges slowly, despite the presence of a compatible adapter.
In this article, we’ll break down all the ways to activate fast charging on the Xiaomi Mi 9, including hidden MIUI settings, checking charger compatibility and solving typical problems. You’ll also learn which Xiaomi’s proprietary adapters support maximum charging speed (27W), and why cheap counterparts can reduce efficiency.
Important: the manual is suitable for all Mi 9 versions (including Mi 9 SE and Mi 9 Lite), but taking into account their technical limitations. For example, the Mi 9 SE supports only Quick Charge 3.0 (18 W), and the Mi 9 Lite supports Quick Charge 4 (18 W).
1. Check support for fast charging on Xiaomi Mi 9
Before you set up settings, make sure your smartphone and charger physically support fast charging technology.
- 🔍 Check the smartphone model: go to Settings → The phone. → Model of the device. Must be specified Xiaomi Mi 9 (codename cepheus).
- ⚡ Check out the power adapter: the original unit from Mi 9 has a marking MDY-11-ED (27 W) or MDY-08-EP (The case must be marked with Quick Charge 4.+.
- 🔌 Use a corporate cable: it will do. USB Type-C from the kit (length) 1 (m) or certified support equivalent USB 2.0/3.0.
If you use a non-original adapter, the charging speed can be limited to the standard 5-10 watts. For example, cheap power supplies often pose as “fast”, but in practice do not support the Quick Charge or USB Power Delivery (PD) protocols.
⚠️ Note: Some users confuse fast charging with Turbo charging function MIUI. The latter is activated automatically at a low battery level (less than 15%) and works only with the original Xiaomi adapters.
2. How to enable fast charging through MIUI settings
In MIUI 10-14 firmware, the fast charging function can be disabled by default to save battery life.
- Open Settings → Battery and Performance.
- Go to Charge (or Charge settings in new MIUI versions).
- Activate the Quick Charge (or Quick Charge) switch.
- If you do not have an option, check the section Additional settings → Charging optimization.
In some regional firmware (e.g. Europe), the item may be called Turbo Charging or Accelerated Charging. If you don’t see these options, then your version of MIUI doesn’t support them – you will need manual activation through the engineering menu (more on this below).
Check the adapter model (should be 18W or 27W)
Use the original USB Type-C cable
Update MIUI to the latest version
Turn off charging optimization (if enabled)
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3. Hidden settings: engineering menu and ADB-team
If standard MIUI settings do not allow you to turn on fast charging, try activating it through the engineering menu or ADB. These methods require caution, since improper actions can disrupt the smartphone.
Method 1: Engineering menu (code ##4636##)
- Open the Phone app and enter the combination: ##4636##.
- Go to the section Information about the battery.
- Check the charge technology line. If it says Quick Charge 4+, but the speed is low, the problem is with the adapter or cable.
Method 2: ADB-Teams (for experienced users)
This method allows you to force fast charging if it is blocked by the firmware:
adb shell settings put global fast_charge 1
adb shell settings put global wireless_fast_charge 1 # for wireless charging (if supported)After you execute the commands, restart your smartphone. If the option does not apply, then your version of MIUI blocks the changes.
What to do if the engineering menu is not opened?
4. Adapter compatibility table for Xiaomi Mi 9
Not all chargers are equally efficient. Below is a table with proven adapters that support the top charging speed on the Xiaomi Mi 9:
| Adapter model | Power | Protocol | Charging speed | Notes |
|---|---|---|---|---|
| MDY-11-ED (original) | 27 Watts | Quick Charge 4+ | ~70% in 30 minutes | Complete with Mi 9 |
| MDY-08-EP | 18 W. | Quick Charge 3.0 | ~50% in 30 minutes | Suitable for Mi 9 SE |
| Anker PowerPort III | 30 Watts. | USB PD | ~65% in 30 minutes | Requires a USB-C 3.0 cable |
| Baseus GaN 2 | 65 W. | USB PD + QC | ~75% in 30 minutes | Supports multiple devices |
| Standard. USB-port | 5 watts | No quick charging. | ~10% in 30 minutes | Not recommended |
⚠️ Note: Using adapters with power over 30W (such as 65W or 100W) will not speed up charging Xiaomi Mi 9, as the smartphone is limited at the level of the power controller. USB PD.
5.Why fast charging doesn't work: typical problems
If you have completed all the settings, but the smartphone is still charging slowly, check the following points:
- 🔋 Battery wear: After 500 charging cycles, the battery capacity decreases and the controller can limit current. → Battery → Battery status.
- 🌡️ Overheating: At temperatures above 40°C smartphone automatically reduces the charging speed. Let the device cool down.
- 📱 Background Processes: Games or Videos in 4K They load the processor, which slows down the charging.
- 🔌 Faulty cable: Damaged wires or connectors may limit current.
Another common reason is the optimization of charging in MIUI, which limits the charge to 80-90% to extend the battery life, and to turn it off:
- Go to Settings → Battery → Charging settings.
- Turn off the option of Charging Optimization or Adaptive Charging.
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If the smartphone charges slowly only under certain conditions (for example, when the screen is on), try activating the aircraft mode while charging, which will reduce the load on the processor and speed up the process.
6. Alternative methods of accelerating charging
If standard fast charging does not give the expected results, try these methods:
- ⚡ Wireless charging: Xiaomi Mi 9 supports Qi charging up to 20 watts. Use a certified station (e.g. Xiaomi Wireless Charging Pad).
- 🔄 Disabling fast charging: Paradoxically, sometimes disabling the option Fast charging in the settings and turning it back on resets the restrictions.
- 📲 Custom Firmware: Some Custom Firmware ROM (LineageOS or Pixel Experience are better at optimizing power management.
For maximum speed, combine 27W wired charging with all background processes shutting down, for example, before charging:
- Activate the Power Saving Mode.
- Close all applications through the recent ones.
- Turn off Wi-Fi, Mobile Data and Bluetooth.
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The most efficient way to charge is to use the original MDY-11-ED (27W) adapter with the screen off and background processes switched off, which can be up to 30-40% in 15 minutes.
7.Fast charging myths: what's true and what's not
There's a lot of rumors going around the Quick Charge technology.
- ❌ Myth 1: “Fast charging ruins the battery” Reality: Modern smartphones (including Xiaomi Mi 9) have built-in protection mechanisms.
- ❌ Myth 2: "You can use any high-power adapter." Reality: A smartphone only takes the current that its controller is designed to use. For example, connecting to a 65W unit will not speed up charging if the device supports a maximum of 27W.
- ❌ Myth 3: “Wireless charging is always slower than wired charging.” Reality: The Xiaomi Mi 9 only has 20–30% slower wireless charging (20W) than wired charging (27W), but is more convenient to use.
The rule of thumb is to use certified accessories and avoid extreme conditions (e.g. charging below 0°C or above 45°C) that will extend battery life regardless of charging speed.