Xiaomi and Redmi smartphone owners often face a situation where the device starts to discharge faster than usual or suddenly shuts down with a charge balance of 10-15%.This is a sure sign that the life of the lithium polymer battery is coming to an end and its real capacity has fallen significantly since the purchase of the gadget. Understanding the current state of the battery is critical to making a decision about replacing the battery or optimizing the system settings.
Unlike some other brands, however, the Chinese manufacturer doesn’t always put detailed wear statistics on the home screen, relying on built-in calibration and optimization algorithms. To get accurate data on how many milliamp hours (mAh) you have left at your disposal, you need to resort to hidden menus, engineering codes or third-party utilities that can read data from the power controller.
In this article, we’ll take a closer look at all the diagnostic techniques available, from simple built-in features to professional tools to help you pinpoint the health of your battery and extend the life of your smartphone.
Check through system settings and the menu “About the phone”
The easiest, but not always informative, way is to go to the standard settings menu of the MIUI operating system or the new HyperOS. In the basic interface, the user usually sees only the percentage of the current charge, but not its physical capacity or degree of degradation. However, some firmware versions have a feature that displays the battery status, which can give a primary idea of the problem.
To access the basic information, you need to go to Settings, then select About Phone. This often indicates the factory capacity of the model, but not the current state. More detailed information can be found in the Safety -> Battery menu, where the system can display temperature and approximate operating time, but the exact wear figures are hidden from the average user.
⚠️ Warning: Don’t blindly trust desktop widgets that show temperature or charge. They often take data from the cache and may not reflect the actual state of the battery cells when the processor is under high load.
If your goal is simply to make sure that the phone sees the battery and it is not identified as "Unknown," then a standard menu is enough, but to diagnose degradation, when the actual capacity falls below 80% of its face value, this method is categorically insufficient, and deeper analysis tools are required.
Use of the engineering menu and USSD-code
One of the most reliable ways to access technical information without installing third-party software is to use special engineering codes. Xiaomi and Redmi smartphones have a hidden menu that allows you to test various components of the device, including the battery.
You need to open the Phone app and dial ##6485#. Once you enter the last star, the screen will automatically switch to the CIT (Customer Information Test) menu. There are a lot of parameters here, but we're interested in specific lines containing battery health data.
- 🔋 MB_06 — It shows the state of the battery (Normal, Good, Bad.
- 📊 MB_00 — shows the current percentage of charge, which may differ from what is in the notification curtain.
- 🏭 MB_01 — current battery voltage in millivolts, an important parameter for diagnosing drawdowns under load.
- 📉 MF_02 — Charging cycle (the number of full charge-discharge cycles) by which we can indirectly judge wear.
Note that newer versions of MIUI 12, 13, 14 and HyperOS may have some fields, such as actual settlement capacity, hidden or zero values for security reasons or driver changes, so ##6485## will only show basic parameters and alternative methods will have to be found.
What if the code doesn't work?
Diagnostics with apps from Google Play
When built-in tools are scarce, specialized monitoring apps come to the rescue, read data directly from the power controller and plot graphs, calculate wear and forecast. AccuBattery is the most popular and time-tested tool for the Android platform.
The software is based on mathematical analysis: the app measures how many milliamp hours were “filled” in the battery during charging, and compares this with a change in the percentage of charge. For example, if the battery entered 2,400 mAh when charging from 20% to 80% (which is 60% of capacity), the program will calculate that 100% of the capacity is 4000 mAh. Comparing this figure with a factory one (for example, 5000 mAh) will show real wear.
It's important to understand that it takes time for an application to get accurate data. You can't just open the program and see the result right away. You have to run several charging and discharging cycles using your smartphone as usual. Only after you accumulate statistics, the app calibration algorithm will give you a reliable health figure (Health) of the battery.
☑️ Proper diagnosis through AccuBattery
Other useful utilities include Ampere (to check charging and discharging current) and Battery Monitor.They may be less accurate in calculating wear, but are great for checking voltage and current strength in real time, which helps to identify faulty cables or power supplies.
Analysis via computer and ADB utility
For advanced users who want to get the most accurate data without installing questionable apps on their phone, there is a method of connecting to a computer. Using the ADB (Android Debug Bridge) debugging bridge allows you to pull raw data from system logs and battery statistics files.
Before starting the procedure, activate the developer mode. To do this, go to Settings -> About Phone and quickly press 7-10 times on the MIUI Version (or OS Version) until the message "You became a developer" appears. Then, in the advanced settings, turn on Debugging over USB.
adb shell dumpsys batterystats | findstr capacityThis command will output lines that contain information about the calculated capacity. However, more informative will be the viewing of the file. battery_history.txt or using specialized scripts that parse the output of the dumpsys batterystats command. In some cases, especially on older versions of Android, you can access the file. /sys/class/power_supply/battery/capacity, Although modern versions of Android restrict direct access to these paths without root rights.
Using ADB is safe for user data, but requires a PC with drivers installed and the ADB utility itself. This method is good because it does not load the phone’s operating system with background processes that can distort energy consumption measurements.
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Use an original or certified USB cable when connecting to a PC for diagnostics. Cheap cables can cause voltage drawdowns, which will lead to erroneous current readings in the system logs.
Table: Comparison of capacity testing methods
To make it easier for you to choose the right diagnostic method, we have summarized the main characteristics of the methods in a single table, which will help you quickly navigate depending on your skills and available tools.
| Method | Accuracy of data | Need for PO | Difficulty |
|---|---|---|---|
| MIUI settings | Low (only per cent) | Not required | Very low. |
| Engineering code | Medium (depending on version) | Not required | Low. |
| Annexes (AccuBattery) | High (takes time) | Installation required | Low. |
| ADB/Computer | Maximum | PC and drivers required | Tall. |
As you can see from the table, for the average user, the best balance between simplicity and accuracy is the use of monitoring applications, which require minimal effort, but give the most complete picture after the period of accumulation of statistics.
Engineering codes are good for quick checks in the here and now, like buying a used device in a store when you don't have time to wait a few days for monitoring. Computer diagnostics is the domain of enthusiasts and service center masters.
Factors Affecting Real Capacity and Wear
Understanding how to know the capacity is useless without knowing why it is shrinking. Lithium-ion and lithium-polymer batteries inevitably degrade, but the speed of this process depends on the operating conditions. The chemical reactions inside the power cell are irreversible, and over time lithium ions lose their ability to move between the cathode and the anode.
The main enemy of the battery is high temperature. Prolonged heating of the body above 40-45 degrees Celsius during games or fast charging accelerates the destruction of the electrolyte, deep discharges to zero and keeping the device completely discharged for a long time are also critical.
- 🌡️ Temperature: Operation in the cold or in direct sunlight.
- ⚡ Charging cycles: Frequent charging in small portions (e.g. with 40% before 50%) less harmful than full cycles 0-100%, but permanent 100% It's not useful under current either.
- 🔌 Charger quality: Using cheap power supplies without protection controllers can lead to voltage surges that destroy the battery structure.
⚠️ Note: If your Redmi phone suddenly turns off when you are on a phone 15-20% And when you're charging, it's not just a sign of the wear of the capacitor, but it's also a possible desynchronization of the charge controller, and a full calibration can help, but it's often a signal for a physical replacement of the element.
The average lifetime of a modern battery in active use is 2-3 years, or about 500-800 full charge cycles, after which the residual capacity usually drops to 70-80% of the original, which becomes noticeable to the user in the form of reduced battery life.
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A sharp drop in autonomy is often due not only to battery wear, but also to background processes or errors in system upgrades. Always check the consumption statistics in the settings before buying a new battery.