How to check the battery on your Xiaomi smartphone: from the code *#*#4636#*#** to disassembling the case

Battery is one of the most vulnerable places in Xiaomi smartphones, especially after 1-2 years of active use. A drop in capacity of 20-30% of nominal value is the norm for lithium-ion batteries, but how do you know that the problem is in the battery, and not in the software or charger? In this article, we will analyze 5 working methods of diagnostics: from hidden engineering menus to hardware tests with a multimeter.

Important: The results of the tests may vary depending on the model (Redmi Note 12 Pro+ or POCO X5), the version of MIUI and the state of the firmware. If after the tests you find critical wear (capacity below 70% of the factory), consider replacing the battery - further operation is fraught with sudden shutdowns and damage to the power controller.

1. Check through the engineering menu (#4636##)

The fastest way to get data about the battery is to use the hidden Testing menu, which is available on all Xiaomi smartphones without root rights, but in the latest versions of the MIUI 14+ can be blocked.

Instructions:

  • 📱 Open the Phone app** and enter the code ##4636##. On some models (e.g. Xiaomi) 13T) You may need to press the call button.

💡

If the engineering menu doesn't open, try the alternative code: ##284## (battery test) or ##6484## (battery test on some models).

Method limitation: the menu shows current values, but not wear history. Use specialized applications for in-depth diagnostics (section 2).

📊 How often do you check the battery status on your smartphone?
Once a month
Only when the problems start.
Never checked.
I use monitoring apps.

2. Diagnostic applications: AccuBattery vs AIDA64

Third-party utilities allow you to track the actual battery capacity, the number of charging cycles and the discharge rate. Two of the most accurate tools are AccuBattery (for wear analysis) and AIDA64 (for technical data).

Comparison of opportunities:

FunctionAccuBatteryAIDA64
Estimation of wear (%)✅ (charge-cycle)❌
Current capacity (mAh)✅ (post-calibration)✅ (Battery section)
AKB temperature✅✅
Voltage (V)✅✅
Discharge history✅ (day-time)❌

How to use AccuBattery:

  1. In the Health section, look at the Estimated Capacity option, compared to passport capacity (e.g., Redmi Note 11 has a 5,000 mAh battery).

Disable battery optimization for the app|Charge your phone to 100% original RAM|Do not use your phone during calibration.|Repeat the test 2-3 times for accuracy-->

Warning: AIDA64 may show lower capacity on new smartphones due to incorrect reading of data from the controller.

3. Visual inspection: when to disassemble a smartphone

If the software methods show critical wear and tear, but you doubt the results, inspect the battery physically, as is the case for models with a removable back cover (Redmi 4A, Redmi 5) or after disassembly.

Signs of a faulty battery:

  • 🔋 Bloating: the lid is raised, the screen is moving away from the frame. Dangerous! This battery can't be pierced or heated - there's a risk of fire.
What to do if the battery is blown?
1. Turn off the phone immediately and remove the battery (if possible). 2. Place the battery in a non-combustible container (such as a metal jar) outdoors. 3. Do not store near heat sources or other electronic devices. 4. Dispose of hazardous waste at the point of reception - do not throw it into ordinary garbage!

To disassemble modern models (Xiaomi 12T, POCO F5) will require:

  • 🛠️ Plastic mediator or screen suction cup.
  • ⚡ Torx screwdriver T3/T4 (model-wise).
  • 🔥 Hair dryer for softening glue (temperature not higher than 80)°C).

⚠️ Note: Disassembly of the smartphone will void the warranty. If the device is warranty, contact the Xiaomi service center with a complaint about the quick discharge - according to the law "On protection of consumer rights" (Article 18), you are required to conduct a free diagnosis.

Multimeter test: measuring voltage and current

For advanced users, the multimeter allows you to measure the actual battery voltage and current consumption, which is useful if the smartphone does not turn on or quickly discharges to zero.

Step-by-step:

  1. Turn off the phone and remove the battery (for non-removable batteries, connect to the contacts on the board).
  2. Transfer the multimeter to DC voltage measurement mode (DCV 20V).
  3. Connect the probes to the AKB contacts: 🔴 Red probe - to plus contact** (+). ⚫ Black probe - to negative contact** (–).
  • 4.2-4.3 V is full charge.
  • 3.7-3.8 V is the average level.
  • 3.0 V and below - deep discharge (requires charging with a special device).

Example of output for a serviceable battery:

level: 85


voltage: 4023 (4.023 V)




temperature: 293 (29.3°C)




health: 2 (Good)

⚠️ Attention: Teams ADB It may vary depending on the version MIUI. On some firmware (Xiaomi.eu), access to battery data is limited, in which case use an alternative command: adb shell cat. /sys/class/power_supply/battery/uevent.

Indirect diagnostics

If you can't do technical tests, look at the behavior of your smartphone, and these signs often point to battery problems:

  • 🔌 Fast charging up to 80% and slow to 100%**: a symptom of battery wear (controller limits current).
  • ⚡ Percentage spikes**: for example, from 50% to 20% in a few minutes, caused by calibration failure or cell degradation.

To check for self-discharge:

  1. Charge your phone to 100% and disconnect from the network.
  2. Turn off Wi-Fi, mobile data and geolocation.
  3. Leave for 6-8 hours in standby mode.
  4. Compare the percentage of discharge with the norm (see the table below).
DowntimeNormal discharge (%)Critical discharge (%)
4 hours0.5–1%More than 3%
8 hours1–2%More than 5%
12 hours.1.5–3%More than 8 percent

FAQ: Frequent questions about checking battery on Xiaomi

Can the battery capacity be restored after wear?
No, lithium-ion batteries are not resuscitable. All methods like "training" charging cycles or using special chargers are a myth. The only way to return the original capacity is to replace the battery with a new one. Exception: if the capacity is understated due to a controller failure (for example, after a deep discharge), calibration will help: Discharge the phone until it is automatically turned off. Charge to 100% without interruption (preferably the original RAM). Repeat 2-3 times.
What is the normal wear of the battery after 2 years of use?
According to Xiaomi standards, the wear is allowed after 500 full charging cycles: 🔋 Up to 20%**: Battery in good condition. 🟡 20-40%**: significantly reduced working hours, recommended replacement. 🔴 Over 40%**: critical wear, high risk of sudden shutdown. Compared to the iPhone battery, the battery is considered worn out when the capacity drops below 80% (according to Apple.
Why does AccuBattery show a capacity of 4500 mAh, although the phone has a battery for 5000 mAh?
That's okay. The app takes into account: 🔋 Real available capacity** after wear. 📉 Losses on the power controller** (5-10% of nominal value). 📊 Measurement error** (especially on non-original batteries) For accuracy, perform a full calibration (discharge to 0% + charge up to 100% without interruption and repeat the test.
Can you use a powerful RAM (67W or 120W) for an old Xiaomi with a worn-out battery?
❌ Not recommended.Fast charging accelerates degradation of worn-out battery due to: 🔥 Increased heat (temperature above 40)°C reduces service life by 30%). ⚡ Increased current, which damages weakened cells.Optimum mode for an old battery: charging 10W–18W (Use the RAM from Redmi Note 8 or similar).
How much does it cost to replace a battery in a Xiaomi service center?
Prices for official replacement (as of the date) 2026 Year: Model Cost (₽) Redmi Note Replacement Time 10/11 1 800–2 500 1–2 Xiaomi 12/13 3 500–4 200 2–3 hour POCO X3/X4 2 000–2 800 1 Black Shark 5 4 000–5 000 3 hour ⚠️ In unofficial services, the price is lower 30–50%, But the risk of installing a substandard battery is higher. Make sure the battery has the original controller (the case must have a sticker with the serial number Xiaomi).