How to charge a phone from Xiaomi: technology and nuances

When a smartphone runs out at the wrong time and the outlet is not available, it is familiar to every user of gadgets. Xiaomi ecosystem owners often wonder whether their device can be used as an external battery for another gadget. Modern technology allows you to implement this feature, turning the phone into a portable charging station.

This is done using OTG technology, which allows you to transmit not only data, but also electric current. However, the process is not always intuitive and requires certain compatibility conditions for ports and versions of the operating system. It is important to understand the physical limitations and software settings so that you do not damage the power controller.

The main tool for connecting the two devices is a special adapter or cable that can transfer power in the right direction, and unlike standard charging, here the donor phone must “understand” that it needs to give power, not take it, which is why a simple connection with a Type-C cable without the support of the appropriate protocols may not work.

It is worth noting that the power transfer rate will be significantly lower than that of a network adapter. The maximum current output through the USB port of a mobile device is usually limited to 2.5 Amperes, which makes the charging process quite slow, but to maintain operation or slow replenishment of the battery in an emergency.

Technological basis for energy transfer

The process is based on the USB On-The-Go standard, which was originally designed to connect peripherals, but in modern implementations allows devices to share power. Xiaomi smartphones, running on the MIUI shell or the new HyperOS, have built-in support for this protocol at the hardware level, which means that the power controller is able to redistribute charge.

When you connect the second device, you have a handshake, where the gadgets define roles, one becomes the host (power source), and the other becomes the customer (consumer). If you're trying to charge a phone from a Xiaomi phone, your smartphone should act as the host. The software shell automatically adjusts the voltage to avoid overload.

There are several fast charging standards, such as Quick Charge or Power Delivery, that can affect the speed of the process. However, when using homemade or cheap adapters, these protocols often do not activate, and the charging is at a minimum speed of 5 Volts. This is a safe but long-term mode of operation.

Equipment and cables required

To do this successfully, you'll need not only two smartphones, but the right accessories. A conventional charging cable that comes with it often has only two contacts to transmit power in one direction, from network to phone, and a cable or adapter labeled OTG is needed to transfer power between devices.

Depending on the connectors of your devices, the configuration may vary. If both phones have a USB Type-C port, you will need a Type-C-Type-C cable that supports current transmission. If the host device has an old Micro-USB connector, you need an OTG adapter with access to Micro-USB. The quality of the cable is critical: cheap analogues can have high resistance.

Below is a table of compatibility of connectors and required cables for various connection scenarios:

It is important to use certified cables, especially if you plan to transmit large currents. Cheap wires can warm and melt, which creates a risk of short circuit. Always check the integrity of the insulation before connecting.

Step-by-step connection instruction

The process of connecting the two devices is physically simple, but requires the right sequence of actions to activate the power transfer mode. First, make sure that the Xiaomi phone that will be the source has more than 20-30% of the battery charged.

Connect the cable. OTG In most cases, the system automatically recognizes the connection and will give a notification of the connection. USB-If you're using an adapter, insert it into your phone first, and then connect the charging cable of the second device to the adapter.

After you've physically connected, look at the screen of the receiving device, and it should show a lightning icon or a charging indication. If that doesn't happen, try unlocking the screen of the donor phone. Sometimes, Android will block the power supply in sleep mode to save money.

⚠️ Warning: If you experience a strong heat in the port area or the smell of burning during the connection, immediately turn off the devices.

In some cases, you may need to manually activate the function. → The phone. → Version. MIUI (Press 7 times to activate Developer Mode, then go to Advanced Settings → For developers, find the item "Debugging by USB» or “Configuration” USB default" and select file transfer or charging mode, although most often it works automatically.

System settings and developer mode

Shell MIUI And HyperOS has an aggressive power-saving system that can interfere with external accessories, and if it doesn't charge, it can be a software problem. USB-Potential threat or simply inappropriate resource expenditure.

For advanced users, there is a developer mode where you can force certain settings. However, be careful: changing the settings you are not sure about can lead to unstable system operation. First of all, check the Settings → Advanced Settings → OTG (if such a item is present in your firmware version).

App permissions are also worth paying attention to. If you use third-party utilities to monitor the battery or control current, make sure they are given the necessary rights. Standard Android tools usually just plug in the cable, but in rare cases, you need confirmation in the pop-up window "Allow access to USB data."

If nothing helps, try rebooting both devices with the cable already connected (if it's safe for the model). USB-Controller freezes and requires restarting system services.

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Use the “Do not turn off screen” mode during charging if the process is slow, which will help to control the temperature and notice connection problems in time.

Limitations and process security

Despite the convenience, the charging method from the phone has its physical and technical limitations, and the main one is the efficiency. When you transfer energy, some of the charge is inevitably lost as heat. 1000 MAC, but the receiving phone will only receive 600-700 It's a law of physics that you can't get around.

The second important aspect is heating. The transmission process heats both devices, the donor phone heats up because of the energy output and the controller, and the receiver heats up because of the incoming current, and the lithium-ion batteries can become overheated, which can lead to degradation or, in the worst case, bloating.

⚠️ Warning: Do not cover your phones with a blanket or pillow while charging from each other. Provide good ventilation so that the heat dissipates naturally.

There is also a risk of draining the donor to zero.If you completely put the Xiaomi phone battery at zero, it may stop turning on without a powerful network charging for some time.

Frequent use of the phone in power-bank mode speeds up wear on its own battery. Charge-discharge cycles go faster and capacity drops more intensely. Take care of your main gadget.

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Using a smartphone as a power bank is an emergency measure, not an everyday habit, as it accelerates the wear and tear of the donor’s battery.

Alternative methods and compatibility

If wired connectivity is not possible or uncomfortable, consider wireless options. Some flagship Xiaomi models support reverse wireless charging. In this case, just put a second phone (supporting the Qi standard) back to the back of the donor, which is more convenient, but even less efficient because of the large energy losses.

To activate wireless reverse charging, you usually need to enable the function in the notification curtain or in the Settings → Battery menu. Make sure there are no cases, metal plates or other items between the cases that prevent inductive transmission.

There are also special applications that supposedly allow you to transfer a charge programmatically, but this is a myth. Software tools can not change the direction of current in physical circuits. Any application that promises to “charge the phone from another over Bluetooth” is fraudulent.

For the constant need for mobile energy, it is better to purchase a compact external battery (Power Bank), which is inexpensive, has a large capacity and does not wear out the battery of your smartphone. Xiaomi phone can be used to recharge the power bank itself when you are at the socket.