The battery is one of the most vulnerable components of the Xiaomi Redmi 9, and after 1.5-2 years of active use, many owners notice that the smartphone discharges 2-3 times faster than after buying. But how to objectively assess the degree of wear of the battery without contacting the service center? There are several ways - from built-in MIUI tools to third-party applications and engineering codes.
In this article, we will discuss 5 proven methods that will help you to know the real state of the battery: from percentage wear to current capacity in mAh. You will also learn what indicators are considered critical, and what to do if the Redmi 9 battery is already "on its last breath." All instructions are adapted for MIUI 12-14 and do not require root rights.
Important: Battery status data may vary slightly depending on the firmware version and modification of the Redmi 9 (e.g. Redmi 9A/9C/9T).
1. Check through the hidden menu ##4636##
The fastest way to get basic battery information is to use Android’s engineering menu, which works on all Xiaomi smartphones, including the Redmi 9, and doesn’t require any additional apps to be installed.
To open the menu:
- Run the standard phone application.
- Enter the combination: ##4636## (no spaces).
- In the window that appears, select Battery Information.
Here you will see the following key parameters:
- 🔋 Level of charge (level) – current percentage in digital form.
- 🔌 Power source – shows whether the charger is connected (USB/AC).
- ⚡ Status – may show Charging, Discharging, or Not charging).
- 📊 Temperature: critical if the value exceeds 40°C to the plain.
- 🔄 Voltage – Normal for Redmi 9 – 3.7–4.3 V.
⚠️ Warning: If the battery voltage drops below 3.4 V at 10-15% charge, this signals severe wear and tear, such a battery can suddenly turn off even when shown 5-10%.
Unfortunately, this menu doesn’t show capacity or percentage of wear — it will require other methods (see the following sections), but you can quickly check whether the smartphone correctly detects charging and whether the battery is overheating.
2.Use of the AccuBattery application: detailed analysis
AccuBattery is one of the most popular battery monitoring apps on Android.It not only shows current wear and tear, but also helps extend battery life by analyzing charging cycles.The app is free (with ads), but key features are available without buying the Pro version.
To check the Redmi 9 battery through AccuBattery:
- Download the app from Google Play.
- Provide all the permissions you have requested (especially access to battery statistics).
- Charge your smartphone to 100% and wait for the app to collect data (usually requires 2-3 charge/discharge cycles).
- Go to the Health tab.
In the Health section you will see:
- 📉 Estimated capacity: The actual capacity of your battery in mAh. For the Redmi 9, the new battery has 5020 mAh.
- ⚠️ Wear: Percentage of capacity loss, for example, 20% means that the battery holds only 80% of its original capacity.
- 🔄 Number of charging cycles - the more, the stronger the wear.
| Depreciation indicator | Battery status | Recommendations |
|---|---|---|
| 0–10% | Excellent. | Continue to use as normal. |
| 10–25% | Satisfactory | Watch the temperature, avoid full discharges. |
| 25–40% | Average. | Consider replacing the battery soon. |
| 40%+ | Critical | Urgent replacement is needed - the risk of sudden shutdown. |
AccuBattery also shows the history of the discharge by application, which helps to identify “voracious” programs, for example, if Google Play Services consumes 30% of the charge in the background, this is an excuse to optimize the settings.
Charge your phone to 100% for calibration|Disable battery optimization for the application in settings MIUI|Check the statistics through 2-3 charging cycles|Compare the figures with the table of wear above-->
3. Check through MIUI Battery Care (built-in tool)
Starting with MIUI 12.5, Xiaomi added a built-in battery monitoring tool, Battery Care, which is less detailed than AccuBattery, but provides basic information without installing third-party software.
How to find Battery Care:
- Open Settings → Battery and Performance.
- Slap the icon. ⚙️ (gear) in the upper right corner.
- Select Battery Health (Battery Health) status.
This will show:
- 📊 General condition – score from “Excellent” to “Bad".
- 🔋 Current capacity - as a percentage of the original.
- 🔄 Number of complete charging cycles.
⚠️ Note: Some Redmi 9 regional firmware (e.g. India or China) may not have a Battery Care section.
If the MIUI shows the battery status as "bad" or the capacity has dropped below 70%, it's a direct signal to replace the battery. Unlike AccuBattery, the built-in tool isn't always accurate, but it gives a general idea of the battery's health.
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If your MIUI version does not have a Battery Care section, upgrade to the latest stable version.Instructions for updating can be found in our MIUI Update Guide.
4. Engineering codes for deep diagnostics
For advanced users who are ready to dive into technical details, there are service codes that reveal advanced battery information.These codes work on most Xiaomi devices, but may vary depending on the version of MIUI.
List of useful codes for Redmi 9:
- 📞 ##6484## - Battery test (shows voltage, temperature, real-time charge level).
- 🔧 ##64663## - Menu testing hardware components, including battery.
- 📊 ##4636## — the already familiar menu with battery information (Battery Information section).
After entering the code ##6484##, you will see a screen with graphs and numbers:
- MB_06 — current battery voltage in millivolts (e.g, 4100 m = 4.1 V).
- MB_05 — temperature.
- MB_01 — Charge level in percentage (may differ from the displayed) MIUI).
If the values MB_06 They are very fluctuating (for example, jumping from the 3.8 Into 4.2 In a few seconds, this may indicate a faulty charging controller or severe battery wear.
What do I do if the codes don't work?
5. Verification through ADB: for experienced users
If you're ready to connect Redmi 9 to a computer, a method using ADB (Android Debug Bridge) will provide the most accurate data about the battery, which requires minimal technical skills, but provides information that is not available through standard tools.
What you need:
- 🖥️ Computer with installed ADB-driver.
- 📱 Included debugging by USB Redmi 9 (path: Settings) → The phone. → Version. MIUI → 7 times to tap according to the version → return to additional settings → For developers → Debugging by USB).
- 🔌 USB-cable (preferably original).
Instructions:
- Connect your smartphone to your PC and open the command line (Windows) or terminal (macOS/Linux).
- Enter the command: adb shell dumpsy battery
- Study the conclusion. We're interested in the following lines: level: 85 - current charge in percentage. voltage: 3987 - voltage in millivolts. temperature: 290 - temperature in tenths of a degree (290 = 29.0 ° C). health: 2 - battery status (codes decoded below).
| The importance of health | Transcription |
|---|---|
| 1 | Unknown (unknown) |
| 2 | Good. Good. |
| 3 | Overheating |
| 4 | Too cold (dead) |
| 5 | The voltage is too high (over voltage) |
| 6 | Unspecified failure (unspecified failure) |
If the health setting is 6, it means that the Redmi 9 battery is faulty and needs to be replaced. Also note the voltage: if it is below 4.0V at 100% charge, the battery capacity has decreased significantly.
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ADB-It's the most accurate way to diagnose, but it requires preparation. If you're not sure about your skills, use apps like AccuBattery or built-in tools. MIUI.
Physical Diagnostics: When Software Methods Are Powerless
If software methods show conflicting results, and the Redmi 9 battery behaves inadequately (for example, suddenly shuts down at 30% charge), it may be a physical wear and tear or battery damage problem, in which case a visual inspection will help.
Signs that the battery needs to be replaced:
- 🔥 Bloating the case -- if the Redmi 9's back cover starts to arch, it's dangerous.
- ⚡ Overheating – if the phone heats up to 50°C+ In simple (checked through the engineering menu).
- 🔌 Unstable charging – the smartphone takes charge, then not, or shows Charging interrupted due to low temperature".
- 📉 A sharp drop in charge – for example, from 50% to 1% in 10 minutes.
To inspect the battery:
- Turn off Redmi 9 and remove the tray for the SIM-map.
- Try to press the back cover slightly in the battery area (center), if it bends or "plays" - the battery is swollen.
- Illuminate a flashlight at the joints of the body - if a gap is visible, this is a sign of deformation.
⚠️ Warning: If you find a battery bloating, you can't: Continue to use your smartphone. Try to prick or compress the battery. Charge the device. Immediately take the Redmi 9 to a battery replacement service center. It's dangerous to keep such a device at home!
The cost of replacing the battery with the Redmi 9 in 2026:
- 🛠️ Official service - 1500-2500 ₽ (battery-powered).
- 🔧 Informal workshops - 800-1500 ₽ (Risk of a poor battery).
- 🏠 Self-substitution 500–1000 ₽ (Only if you have experience in disassembling smartphones).