How to check the battery capacity of Xiaomi

Modern smartphone users have high demands on autonomy, and owners of Xiaomi devices are no exception. Over time, battery capacity inevitably decreases, leading to faster discharge and the need to recharge frequently throughout the day. However, the standard MIUI or HyperOS interface does not always provide accurate information about the real state of the energy storage device, limited only by the percentage of charge.

Understanding how to test battery capacity on Xiaomi is key to diagnosing power problems, which allows you to distinguish a software failure from physical wear and tear of a battery and decide whether to replace it or optimize settings. There are several proven methods to look under the hood of an operating system and get reliable data.

In this article, we will take a look at all the available methods, from simple built-in features to using the engineering menu. You will learn what secret codes work on current versions of Android, how to read specifications through hidden settings and why capacity data may differ across applications. Accurate diagnosis is the first step to extending the life of your gadget.

Using secret codes for diagnosis

The fastest way to access technical information about the status of the battery is to use the battery. USSD-Xiaomi smartphones, like many Android devices, have codes that open hidden diagnostic menus. The most common way to check the battery is to use a combination that triggers an engineering menu or phone information.

You need to open the standard Phone app and dial ##6485##. Once you enter the last star, the menu should open automatically, go to dial mode, and if the code doesn't work, try the alternative #4636##, which opens the test menu, where you can also find the Battery Information section.

And you'll see a lot of parameters in the window that opens, with acronyms, and we're interested in the lines that contain the capacitance information. MF_05 (current-charge), MF_06 (calculation capacity) and MF_02 (It is important to understand that not all models support displaying all of these fields, and some values may be zero.

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If ##6485## does not open the menu, your MIUI version may be blocking that access. Try entering the code in the Phone app through the typing app instead of through contact searches.

⚠️ Note: Some global versions of the firmware MIUI HyperOS access to the engineering menu through USSD-The codes may be blocked by the manufacturer for security reasons, in which case the use of the codes will not work.

It is worth noting that the data in the engineering menu is not updated instantly. If you just connected the charger, the figures may be incorrect. To get the most accurate data on the real capacity, it is recommended to check after the phone has been battery-operated for at least a few hours.

Analysis of parameters through the menu "About the phone"

A simpler, less informative method is to look at the basic information in the system settings. Here you won't see the exact percentage wear, but you can find out the passport capacity declared by the manufacturer and compare it with the experience of using. To do this, go to Settings → About Phone → All settings.

In the specs list, find a line describing the battery. Usually it shows a rated capacity, like 5,000 mAh or 4,500 mAh. This is the reference value for your Redmi or Poco model. Knowing this figure, you can indirectly estimate wear and tear: if a phone with a new battery held charge for two days, and now barely survives until the evening at the same activity, the wear and tear is obvious.

But this method has a significant drawback: it doesn't show the current state of the chemical composition of the lithium cells. It can show 100% charge, but because of the degradation of the voltage under load, the phone can turn off at 15-20%, so it's more suitable for initial familiarization than for deep diagnostics.

For a more detailed analysis in this section, it is sometimes useful to look at the kernel and build version. If you upgrade to a new version of MIUI and notice a sharp drop in battery life, the problem may not be in the battery, but in the optimization of the system. In such cases, resetting settings or waiting for a patch often helps more than replacing the battery.

Checking through the hidden Battery Assistant menu

In the MIUI shell, there's a hidden system application called Battery Assistant, which has detailed statistics, and you can access it through settings or a special label, and it shows not only the current charge, but also the number of recharge cycles, which is a direct indicator of the battery life.

To get into this menu, follow the Settings → Battery → (three dots or gear) → Statistics. In some versions of the firmware, the path may be different: Settings → About Phone → All Options → Press 5-7 times on the “Kerole Version” (although more often this opens the developer menu, in older versions of MIUI worked for the battery).

In the interface that opens, pay attention to the following parameters:

• 🔋 Current capacity – current charge in milliamp hours.
• 🔄 Cycle count – number of full charge-discharge cycles.
• 🌡️ Temperature – current battery temperature (critical for Li-Ion health).
• ⚡ Voltage - voltage at the terminals of the battery.

The number of cycles is a crucial indicator. Lithium polymer batteries used in Xiaomi usually retain 80% of the capacity after 500-800 full cycles. If the meter shows 1000+ and the phone holds a charge poorly, this is a clear sign of the need to replace.

Calibration is also often available on this menu, and if you notice that the percentage of charge jumps (for example, from 20% to 5%), using built-in calibration tools can help the system learn how to correctly estimate the level of charge.

Use of third-party applications

When built-in tools aren't enough, Google Play comes to the rescue, and apps like CPU-Z, Ampere, or Battery Guru can read data directly from the power controller, bypassing the interface constraints, and provide the most accurate picture yet.

One of the best programs is CPU-Z. Once installed, launch the application and go to the Battery tab. Here you will see:

• ⚙️ Health - Battery status (Good, Overheat, Dead).
• 📉 Technology - a type of technology (Li-poly, Li-ion).
• 📏 Capacity - the calculated capacity.
• 🔌 Power source - Power source (AC, USB, Wireless).

Another powerful app is Ampere, which is useful because it shows the real strength of current when charging and discharging, which allows you to detect not only battery wear, but also problems with the charging cable or Xiaomi power supply. If the charging current is significantly lower than stated (for example, 0.5A instead of 2A for fast charging), the problem may be in the accessories.

⚠️ Warning: Third-party applications require permanent permissions to access system data, which may slightly increase energy consumption, and it is recommended to use them only for diagnostics, rather than keeping them running constantly.

It's important to understand that no application can magically restore a battery or accurately measure its capacity without a full discharge cycle. The data they show is calculated based on voltage and resistance. However, they are ideal for comparing degradation dynamics.

Table of comparison of verification methods

To organize your knowledge and choose the best diagnostic method for your situation, consider a comparison table of methods. Each of them has its advantages and limitations depending on the model of the Redmi Note or the flagship Mi.

As you can see from the table, secret codes give you the fastest access to hardware, but they can be blocked. Applications give you convenient statistics, but they require installation. Combining these methods gives you the most complete picture.

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The most reliable result is a combination of data from the engineering menu (codes) and readings from a specialized application like CPU-Z for cross-checking.

If the app shows wear and tear of 10% and codes of 40%, you should conduct an additional calibration cycle or contact the service to measure the capacity with a tester.

Physical wear and signs of degradation

Software techniques are good, but the physical state of the battery often speaks more than the numbers on the screen. Over time, the chemical processes inside the cell lead to irreversible changes, and understanding these signs will help you respond in time and avoid trouble, such as bloating or a sudden shutdown.

Note the following symptoms that indicate critical battery wear:

• 📱 Bloating of the case – the back cover or screen began to move away from the frame.
• 🔥 Overheating – the phone warms up strongly even with simple tasks (browser, calls).
• ⚡ Percentage jumps – charge drops from 30% to 1% in a few minutes.
• 🔌 Charging problems – the phone only charges in a certain position of the cable.

Bloating is the most dangerous sign. Gas builds up inside the Li-Pol battery, which can cause fire or damage to the display, and if you notice that the phone is no longer flat on the table and spins when you are jolted, stop using it immediately.

It's also worth considering the age of the device. Even if you haven't used a phone, but it's 3-4 years old, the chemistry inside could be degraded. Storing a fully discharged or fully charged phone speeds up the process. The optimal storage level is about 50-60%.

FAQ: Frequently Asked Questions