Many Xiaomi smartphone owners often face confusion about the names of power functions, especially when it comes to wireless power transfer technology. Xiaomi Redmi Note 9, released in 2020, is a popular device of the mid-range, but its capabilities in the field of wireless energy have their own characteristics.
This means that your phone can work as a power bank for other gadgets, but it can’t charge itself from the mat. In this article, we’ll detail how to activate the power transfer mode, what MIUI settings you need to check and why the feature may not start. Understanding these nuances will help you effectively use the device’s battery pack to power your headphones, watches or other smartphone in an emergency.
Before you start setting up, make sure you have a clear understanding of the difference between receiving and transmitting power. The Redmi Note 9 can only give a charge to other devices, but cannot receive it wirelessly. This is a critical technical limit that determines all the logic of how to proceed with the system interface.
Technical limitations and support for standards
Redmi Note series smartphones are traditionally focused on the mass user, so manufacturers often save on the introduction of induction receiving coils. The specifications of the Redmi Note 9 indicate the presence of a battery with a capacity of 5020 mAh and support for fast wired charging with a capacity of 18 watts. However, the module for receiving energy according to the Qi standard in the design of the case is missing.
Despite this, Xiaomi engineers have implemented a chip that allows you to use your phone as an energy donor, a feature known as Wireless Power Share or reverse charging. It is software-activated and requires the appropriate hardware from the receiving device. If you try to put your Redmi Note 9 on the charging station, nothing happens, because the power controller simply does not recognize the external electromagnetic field.
It is also worth noting the impact of the MIUI software shell on energy-saving functions: the system can block power transmission if the battery level is below a certain threshold or if the processor temperature is too high, a protective mechanism that prevents overheating and deep rupture of the lithium-polymer battery.
⚠️ Warning: Do not try to use third-party apps from the Play Market store that promise to "unlock" wireless charging reception. This is a software impossibility, as the device does not physically have the necessary hardware module.
Activation of reverse wireless charging
For your smartphone to start transmitting power, you need to manually start the service in the system, which is disabled by default to save resources, the activation process takes a few seconds and does not require root rights or flashing the device.
First, unlock the screen and lower the notification curtain. You need to find an icon that could be called "Wireless Reverse Charging" or "Wireless Reverse Charging." If you don't have it in Quick Access, go to the main settings menu, and you should select the Battery and Performance section or simply the Battery, depending on your MIUI firmware version.
Inside the battery menu, find the power switch, and when it's activated, the phone will go into standby mode, and you may see a special animation or countdown timer that signals you're ready to go.
☑️ Pre-launch checks
If the charge is below 30%, the system will issue a warning and refuse to turn on the transmission mode, this is done to ensure that you do not remain completely discharged at the right time.
Configuring energy saving parameters
Android and MIUI aggressively control background processes. To keep the backcharging running smoothly and not interrupted after a few minutes, it is recommended to check the optimization settings. Go to Settings → Applications → All Apps.
Find a battery-related or wireless charging system process (often hidden or integrated into system services) on the list, and make sure it doesn't have a background limit. Although this process is automated in the latest versions of MIUI 12/13/14, manual control is a good option.
Also worth paying attention to is the power saving mode. If the Ultra-Energy Saving mode is on, the power transmission function can be forced off by the system. Switch to Standard Operating Mode or Performance Mode to remove the limits on the recoil current.
| Parameter | Recommended value | Impact on work |
|---|---|---|
| Charge level | More than 30% | Low-charge locking |
| Temperature. | To 45°C. | Overheating shutdown |
| Screen. | Off. | Reduced efficiency with the display on |
| Flight mode | Included (recommended) | Reduces heat and interference |
Why is the phone heating up?
Compatibility of devices and covers
Not all gadgets can take charge wirelessly. To successfully transfer power, the receiving device must support the Qi standard. These are usually flagship smartphones, modern TWS headphones (such as AirPods, Galaxy Buds), and smartwatches.
The thickness and material of the protective case have a huge impact on the charging efficiency. Metal inserts, magnetic rings or simply very thick silicone can block the electromagnetic field, in which case charging will either not start or will go at a very low speed and high heat.
The centering of the devices is also key: the power transmission coil in the Redmi Note 9 is located in the central part of the back panel, and the receiving device needs to be placed exactly in the center to ensure maximum contact area of the fields.
- 📱 Make sure that the receiver supports the Qi standard.
- 🛡️ Remove thick or metal covers from both devices.
- 🧹 Wipe the back covers from dirt and dust before contact.
- 📍 Place the devices strictly in the center relative to each other.
If you use a magnetic-based ring case, you have to remove it. Magnets create interference and can damage the power controller if you have prolonged active contact.
Diagnostics and troubleshooting
Often users are faced with a situation where the function is turned on, but charging is not going. First of all, check the indicator on the receiving device - is it on? If not, perhaps the problem is on the client side. Try charging another device from your Redmi Note 9 to prevent the donor from breaking.
The second common cause is a software failure of power management, in which case the banal smartphone reboot helps. Once the system is turned on, re-activate the recharging function. It is also worth checking for system updates in the About Phone → MIUI version.
If the phone is rapidly discharged or warmed up even without the connected device and the function is active, it may have been a "stick" process in the system. Try clearing the cache of system applications or resetting the network settings, although this is extremely rare.
⚠️ Warning: If the back cover of the phone is swollen or there is a strong local heating in the area of the camera, immediately stop using the feature and contact the service center.
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To speed up the charging process of another device, turn on the Redmi Note 9 mode "Flight". This will turn off the communication modules, reduce the heat of the processor and direct more power to the output coil.
Effects of ambient temperature
The Lithium Polymer batteries installed in the Xiaomi Redmi Note 9 are sensitive to external conditions. The optimal temperature range for the return charge function is from +10 °C to +35 °C. In the cold, the chemical reactions inside the battery slow down, and the controller can block the current return.
In the summer, in hot weather, the risk of overheating increases many times over, the energy transfer process is inherently inefficient (about 60-70%), and most of the energy is converted to heat. If you're in the direct sun, the system can interrupt the process to prevent the battery from bloating.
In the cold season, it is recommended to warm the phone in your hands or pocket before trying to charge your headphones or watch. The warm environment will provide a more stable current return and prolong the life of the battery.
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Temperature is a critical factor in stability. Do not use reverse charging in extreme cold or in the scorching sun, so as not to damage the battery irrevocably.