How to turn off fast charging on Xiaomi Mi9 Pro

Owners of flagship smartphones such as the Xiaomi Mi9 Pro often face the need to limit the speed of energy input into the battery. Modern fast charging technologies such as Quick Charge or proprietary HyperCharge allow you to recharge the battery in minutes, but at the same time significantly heat the device. High temperature is the main enemy of lithium-polymer batteries, reducing their resource and causing degradation of chemical composition over time.

That is why many users prefer to sacrifice speed for the longevity of the gadget, especially at night or when charging from a portable power bank. The standard MIUI shell does not always provide an obvious button to completely turn off the accelerated mode, which creates the illusion that this is not possible.

In this article, we will go into detail about the software and hardware solutions to the problem, and explain why heating above 40 degrees when charging is considered critical for the Mi9 Pro.

Why limit the charging speed

The main reason for the failure of maximum speeds lies in the physical and chemical processes that occur inside the battery. When using powerful adapters with a capacity of 30 watts, which supports Xiaomi Mi9 Pro, intense heat release occurs. If you charge the phone in a case or in a hot room, the heat sink deteriorates, and the battery is subjected to thermal stress.

In addition, fast charging is most active in the range from 0 to 70-80% of capacity. In this range, voltage and current are maximum, which puts a strain on the power controller. Speed limiting allows you to distribute this process over time, reducing the peak load on the electronic board of the device.

There is also a scenario of using low-power power supplies for overnight charging, in which case the phone charges more slowly, avoiding the effect of micro-cycling and overvoltage at the top of the charge chart.

Software settings of the MIUI shell

The first thing a Xiaomi Mi9 Pro user needs to do is check the built-in optimizers. Some versions of MIUI firmware have hidden or explicit switches that affect the power controller. Although there is usually no direct button to turn off fast charging, you can activate power saving modes.

Go to Settings → Battery. This is the Power Savings switch. When activated, the system restricts background processes and can reduce consumption current, which indirectly affects the incoming current when connected to the grid. In super-economy mode, charging often occurs at standard USB 2.0 speeds (5V/1A or 2A).

You also need to pay attention to charging optimization settings, which can analyze your habits and slow down the process at certain stages to extend the life of the battery, which is not a complete shutdown, but a useful feature for everyday use.

• 🔋 Turn on the "Energy Saving" mode to reduce consumption currents.
• ⚙️ Check the settings in the "Security" section» → «Battery».
• 🌙 Activate Night Mode or Power Savings Enablement Schedule.

Use of the engineering menu

For a deeper intervention in the operation of the Xiaomi system Mi9 There's an engineering menu called Pro, and it's a hidden section that's designed to be used by engineers to test the hardware, but it's also accessible to the general public. USB-port-loading.

To get into the menu, open the Phone app and dial the combination ##6484##. If the code doesn't work, your firmware version may be blocking access, in which case you can try activating the menu through the Engineering Menu app from the app store, if it's compatible with your Android version.

Inside the menu, you should look for a section related to Battery or Charging, which can be called differently depending on the version of the kernel, and be careful: changing unknown parameters can lead to malfunctioning of the device.

⚠️ Warning: Change the settings in the engineering menu is at your own risk%.

The parameter that we're most interested in is often hidden under a name related to USB current restriction or QC (Quick Charge) switching. If you find a Disable Fast Charge or similar option, activating it will force charging to standard 5B mode.

Effects of cable and power adapter

The easiest and safest way to disable fast charging on the Xiaomi Mi9 Pro is to use the wrong hardware. Rapid charging protocols like Qualcomm Quick Charge or USB Power Delivery only work when there is a smart dialog between the adapter and the phone.

If you connect your phone to your computer through a normal USB-port or use an old adapter on the 5V/2And without support for voltage-boosting protocols, the phone won't physically be able to charge quickly. - Xiaomi's power controller Mi9 Pro will automatically determine the source capabilities and select the safe mode.

Cable also plays a major role, and low-quality cables, thin cables, or cables over 1.5 meters long, have high resistance, which prevents the current required to activate fast charging, and the phone will go into normal mode.

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Use cables without QC or PD labeling to automatically reduce charging speeds without your phone settings.

Third-party control applications

If the system settings don’t work, you can use third-party software. Google Play and other repositories have applications that manage charging. However, on modern versions of Android (and the Mi9 Pro runs on current versions of the OS), access rights are limited.

Applications like Battery Charge Limit or AccuBattery can't programmatically cut off incoming current at the controller level without root rights, but they can help you control the process, such as setting up a notification or automatic action when you reach 80% charge, so that you disconnect the device from the network in time to avoid overcharging.

For devices with Root rights, the possibilities are expanding, and there are Magisk modules and scripts that can directly interact with kernel configuration files, preventing the activation of fast charging protocols.

• 📱 AccuBattery – Health and Speed Monitoring.
• 🔒 Battery Charge Limit – requires root, can stop charging.
• ⚙️ Kernel Adiutor – for advanced kernel settings (root only).

Protocol compatibility table

Understanding which protocol your adapter uses helps in choosing the method of disabling.The Xiaomi Mi9 Pro supports many standards, and locking one doesn't always mean turning everyone off.

Below is a table showing how different equipment combinations affect the final power, which will help you pick a cable-block pair for slow charging.

⚠️ Attention: Use of poor-quality cables with powerful power supplies can lead to a voltage drop and unstable operation of the charging circuit, which is sometimes more dangerous than fast charging.

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The most reliable way to disable fast charging is to use a weak power supply (5V/1A or 5V/2A) without support for QC/PD protocols.

Frequently Asked Questions (FAQ)