How to check the battery status of Xiaomi Mi 9T: from wear to capacity

Why it’s important to keep an eye on the Mi 9T battery and when to change it

The battery is the most vulnerable component of the Xiaomi Mi 9T (codenamed davinci). Even when used carefully in 2-3 years, its capacity is reduced by 20-30%, and battery life is reduced by half. The reason lies in the chemical processes: lithium-ion batteries degrade from charging cycles, high temperatures and deep discharges. If your smartphone discharges in 4-5 hours with moderate use or turns off by 20-30% of charge, these are clear signs of wear.

But how do you accurately measure the state of a battery without disassembling a phone? In this article, we'll discuss 5 working methods -- from hidden ones. USSD-You'll learn how to check the actual capacity (in mAh), the number of charging cycles and even the temperature of the battery in real time, and at the end you'll see a table with the rates of wear and recommendations when to change the battery.

⚠️ Important: Mi 9T It has a 4000 mAh battery, which is standard. If the applications are below 3200 mAh (80% of the original), the battery life of the device will drop by 40-50.

Method 1: Check through the engineering menu (#4636##)

The fastest way to get data about the battery is to use the hidden Android engineering menu, which is available without root rights and additional applications.

1. Open the Phone app.
2. Enter the combination: ##4636###.
3. In the menu that appears, select Battery Information.

Here you will see the key parameters:

• 🔋 Level of charge (level) - current percentage.
• 🌡️ Temperature (Temperature) - in tenths °C (e.g, 325 = 32.5°C).
• ⚡ Voltage – should be in the range of 3.7-4.2 V at 100% charge.
• 📊 Health – usually displayed as Good, but it is not a sign of wear and tear!

⚠️ Warning: The engineering menu doesn't show the actual capacity or number of charging cycles. This requires specialized utilities (see Methods 3 and 4).°C when charging is the norm for Mi 9T Support for Quick Charge 4+.

Method 2: USSD-battery-diagnostic

Xiaomi hides some of the diagnostic data for the USSD-These codes work on Mi. 9T original-fixed MIUI (including the global and Chinese versions. Try the following combinations:

🔍 What to look for in the results:

• 📉 Voltage: below 3.5V at 20% charge - a sign of wear and tear.
• 🔥 Temperature (temperature): above 45°C without loading - a possible defect.
• ⚠ Status: If Unknown or Dead is displayed, the battery is faulty.

⚠️ Attention: Not all USSD-codes run on custom firmware (like LineageOS or Pixel Experience), and if nothing happens after you enter the code, your firmware has blocked diagnostic commands.

💡

If USSD-codes do not work, try to enter them through the application "Phone" in dial mode, and not through a search system.

Method 3: Applications for deep diagnostics (AccuBattery, CPU-Z)

To accurately analyze the battery status of the Mi 9T, we recommend using third-party utilities that show real capacity, the number of charging cycles, and even predict the remaining life.

1. AccuBattery (free, no root)

This app tracks the actual battery capacity and teaches you how to charge your smartphone correctly.

1. Charge your phone to 100% and calibrate the app.
2. Use your smartphone as usual for 2-3 days.
3. Go to the Health tab - the current capacity in mAh will be displayed there.

2. CPU-Z (free, no root)

Shows the technical data of the battery, including:

• 🔋 Level of wear (in %).
• 📊 Technology (for Mi) 9T It's a Li-ion).
• 🔄 Number of charging cycles (if supported by firmware).

📌 Comparison of applications:

⚠️ Note: Root-free applications can show estimates rather than exact values from the battery controller. 100% accuracy requires root or specialized hardware (e.g. USB-Tester).

Method 4: Checking through ADB (for advanced users)

If you are ready to use Android Debug Bridge (ADB), You can get advanced data about the battery directly from the controller. ADB-Drivers and computer. Instructions:

1. Enable Developer Mode on Mi 9T: Go to Settings → About Phone. 7 times click on MIUI Version. Return to Settings → Additional → Developer. Activate Debugging on USB.

adb shell dumpsys battery

📋 What to look for in conclusion:

• 🔋 Capacity is the current capacity in percent, but it's not a measure of wear and tear!
• 🔄 charge counter – the amount of charge in μAh (divided by 1000 to get mAh).
• 🌡️ Temperature - temperature in tenths °C.
• ⚡ Voltage - voltage (mV) (e.g, 4123 = 4.123 V).

💡 Example of inference:

level: 85


scale: 100




status: 2 (Charging)




health: 2 (Good)




present: true




voltage: 4023 mV




temperature: 320 (32.0°C)




technology: Li-ion




charge counter: 3200000 (3200 mAh)

⚠️ Note: The charge counter value can be reset after rebooting or updating the firmware. For an accurate analysis, compare it to the passport capacity (4000 mAh for Mi). 9T).

Method 5: Visual Diagnostics and Physical Signs of Wear

Sometimes you can evaluate the battery without software, by external signs.

• 🔥 Overheating: if the body Mi 9T heats up above 50°C without load (e.g., standby), this is a sign of battery degradation or short circuit.
• 📉 Sudden shutdowns: The phone shuts down 20 to 30% of the charge due to incorrect controller calibration.
• 🔌 Slow Charging: If Quick Charge 4+ (18 W) charges the smartphone longer than 2 hours, possible wear of the battery.
• 💥 Bloating of the body: if the back cover Mi 9T Begin to bend or gaps appeared - the battery needs to be replaced urgently!

🔧 How to check for bloating:

1. Place your phone on a flat surface (such as a table).
2. Easy press the center of the back cover.
3. If the body is "playing" or a crunch is heard - the battery is swelled.

⚠️ Attention: Bloated battery is a risk of fire. Don't try to puncture or bend it! Contact Xiaomi Service Center or Authorized Workshop.

💡

If the battery is swelling, it can't be used -- even if the phone is still turning on -- and lithium-ion batteries in this state can ignite when heated or mechanically exposed.

Table: Battery wear standards and recommendations

To see if it’s time to change the Mi 9T battery, compare the figures with this table:

💡 Tip: If the battery capacity has dropped below 3200 mAh, but you are not ready to change it, try calibration:

1. Discharge the phone before automatically shutting down.
2. Charge up to 100% without interruption (use the original adapter).
3. Repeat the cycle 2-3 times.

This may temporarily improve performance, but it will not restore capacity.

FAQ: Frequent questions about the Xiaomi Mi battery 9T