How to enable fast charging on Xiaomi Mi 9 with NFC

Xiaomi Mi 9 was one of the first devices of the company to receive support for wired fast charging technology with a capacity of 27 watts. This is a significant advantage, allowing you to replenish the battery capacity of 3300 mAh in just an hour, but many users are faced with the fact that the gadget is charged at a standard speed. Often the reason lies not in the breakdown, but in hidden settings or inappropriate accessories.

Owners often confuse the fast charging function with wireless data transmission or NFC module, believing that their presence has some effect on the power supply. In fact, these are independent modules, but in the context of the Mi 9 model they coexist in close physical proximity, since the wireless charging coil and the NFC antenna are located on the back, understanding their operation will help to avoid errors in operation.

In this guide, we will discuss in detail the software aspects of activation of accelerated charge, hardware requirements and possible software conflicts, you will learn how to diagnose a problem if the lightning indicator does not appear, and what settings in the MIUI shell can block maximum power.

Software activation of the function in MIUI

Unlike some other manufacturers, Xiaomi doesn’t always display the fast charge switch prominently in the main settings menu.In the Mi 9 model, this feature is often activated by default, but can be deactivated by the system to extend battery life or after a firmware update.

Go to Settings, then select Battery and Performance, and you should look at the button that shows the gear in the top right corner of the screen, and that's where the key power management parameters are hidden inside the submenu, and if the Speed Charging slider is turned off, you need to manually activate it.

⚠️ Warning: Forced activation of maximum power on a worn-out battery can cause it to overheat.The system will turn off fast charging itself if temperature sensors detect critical values.

It’s also worth checking for system updates. Sometimes bugs in older versions of MIUI block Quick Charge protocols. Go to Settings → About Phone → MIUI version and press the Update Check button. Make sure you have the latest stable firmware installed, as Xiaomi engineers regularly release patches that optimize the power controller.

Requirements for charger and cable

Even if the software is set up correctly, physical hardware plays a crucial role.The Xiaomi Mi 9 smartphone supports Quick Charge 4.0+ and the proprietary protocol Xiaomi Charge Turbo. Using a conventional power supply from an old phone or a cheap analog with 5 W or 10 W will not allow you to start the accelerated charging mode.

Cable is also a critical link in the circuit. High-power currents (over 2 Amps) require wires labeled 3A or 5A. Thin cables bundled with budget devices have high resistance, resulting in a voltage drop and automatic reduction of current by the smartphone controller.

• 🔌 Use the original power supply unit with at least 27 watts of power with support USB Power Delivery.
• ⚡ Replace the cable if it is longer than 1.5 meters, as this increases energy loss.
• 🛡️ Avoid damaged wires with insulation fractures, they can cause voltage surges.

Notice the USB Type-C connector in the smartphone itself, which eventually accumulates dust and pile from your pockets inside the port, which prevents the contacts from contacting tightly, which is a common reason why the phone doesn't see the fast charger and goes into safe mode with minimal current.

The Impact of NFC and Wireless Charging on the Process

Xiaomi Mi 9 features a wireless charging module that is physically located on the back of the NFC antenna. Users sometimes wonder if active NFC affects the charge rate. Technically, constant tag search or card emulation mode puts additional strain on the processor and radio module, which can slightly increase the temperature of the case.

When the device is heated above a certain (usually around 40-45 degrees), the BMS (Battery Management System) artificially lowers the charge current to prevent damage to the elements.So if you have multiple background services, GPS and active NFC on in constant scanning mode, the phone can charge more slowly.

For maximum speed, it is recommended to transfer the smartphone to flight mode during charging, or at least turn off geolocation and NFC. This will reduce heat generation and allow the power controller to maintain maximum current for more time.

Diagnosing problems through the engineering menu

If standard methods don't work, you can use a hidden engineering menu to check battery status and charge, which will allow you to see the real current and voltage entering the battery, and see if the fast charging protocol works.

To enter the diagnostic menu, dial the phone application code ##6484##. From the list that opens, select Battery info or Charging test. This displays the current parameters: Voltage and Current. With normal charging, the current is about 0.5-1.0 A, and with fast charging, it increases to 2.5-3.0 A and higher.

If the USB status bar indicates SDP or CDP, then the phone has not agreed with the charger to switch to fast charging mode (DCP or HVDCP), in which case the problem lies in the cable or power supply, since the software phone is ready to go.

Optimizing settings to extend the service life

Continuous use of a maximum power of 27 watts can reduce the life of a lithium polymer battery. Modern versions of MIUI have implemented adaptive charging algorithms that learn your habits and can slow down the process at night to complete charging by the time you wake up.

It is recommended to activate the function "Optimize night charging" in the battery menu, this will not speed up the process, but will keep the battery healthy for years, also avoid the discharge of the device below 10% and try not to keep it on charging at 100% for too long, especially in hot climates.

💡

Use In-Aircraft mode during fast charging, if you want to charge your phone as fast as possible, this will turn off all radio modules, reduce heating, and allow the power controller to run to the limit without temperature restrictions.

Remember that a top speed of 27 watts is achieved only when the screen is completely off and there are no running applications. If you use the phone while charging, the system will automatically reduce the current to compensate for the power consumption of the screen and processor.

Frequently Asked Questions (FAQ)

💡

The main factor of success is a bunch of original power supply 27 watts and high-quality cable with a bandwidth of 3A. Without this pair, the software settings will not give a result.