Xiaomi Redmi 4X (codenamed santoni) is one of the brand’s most popular budget smartphones, released in 2017. After 5-7 years of active use, its 4100 mAh battery inevitably degrades: loses up to 30-50% of its original capacity, discharges faster and charges longer. But how do you know exactly how worn out the battery is? In this article, 7 proven diagnostic methods, from hidden engineering menus to disassembly of the case.
We'll not only look at software methods (via MIUI, apps like AccuBattery or AIDA64), but also physical methods, such as how to estimate battery bloating without opening, why Redmi 4X can suddenly turn off at 20-30% charge, and what to do if the smartphone doesn't hold a charge for more than an hour, and all instructions are adapted to the original and custom firmware, including MIUI versions 9-14.
1. Check through the engineering menu (#4636##)
The fastest way to get data about the battery is to use a hidden engineering menu, which is available on all Xiaomi smartphones, including the Redmi 4X, but requires caution: do not change the settings if you are not sure of their purpose!
How to open it:
- 📱 Open the phone app and enter the combination: ##4636##.
- 🔧 In the menu that appears, select Battery Information).
- 📊 Note the parameters: Level – current percentage; Status – should be Charging (charged) or Discharging (discharged); Battery Health – ideal Good; Temperature – norm from 25°C to 40°C.
⚠️ Warning: If the Health field says Unknown, Dead or Overheat, the battery is critically worn or damaged, in which case the smartphone may turn off when the charge is low or not at all.
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If the engineering menu does not open, check if access to hidden settings in MIUI is disabled. To do this, go to Settings → Additional → Developer and activate the option Unlock OEM (if available).
2. USSD codes for battery diagnostics
In addition to the standard engineering menu, the Redmi 4X also has additional service codes that provide advanced information about the charging cycle and the actual capacity.
List of useful teams:
- 🔢 ##6484## - battery test (MTK Battery Test);
- 🔢 ##64663## - Information about the power module;
- 🔢 ##36446337## - Temperature and voltage data;
- 🔢 ##2846579## → ProjectMenu → Battery - advanced diagnostics (does not work on all firmware).
Once you enter the code ##6484##, you will see a window with a discharge graph and a Battery Capacity setting. Compare it to a factory value of 4100 mAh:
| Capacity index | Battery status | Recommendations |
|---|---|---|
| 3800-4100 mAh | Excellent. | The battery is almost new. It's enough to calibrate once every 3 months. |
| 3000–3799 mAh | Average. | Wear ~20-30%. Watch the temperature, avoid full discharges. |
| 2000-2999 mAh | Critical | Capacity dropped 40 percent+. Get ready to replace the battery. |
| Less than 2,000 mAh | Emergency. | A smartphone can shut down at 30 to 50 percent charge. Replacement is required. |
⚠️ Note: Some custom firmware (such as LineageOS or Pixel Experience) may not have service codes.
3. Applications for battery testing
If the engineering menu is not available or the data is too scarce, install specialized utilities that analyze charging cycles, temperature and real capacity.
Top.-3 supplant 4X:
- 📊 AccuBattery - shows wear, discharge rate and charging history. Free version limited to 500 mAh data.
- 🔍 AIDA64 — displays the technical parameters of the battery, including voltage, technology (Li-Po) and factory capacity.
- 📉 Battery Guru - monitors the temperature and warns about overheating, useful for diagnosing bloating.
Instructions for using AccuBattery:
- Download the app from Google Play.
- Connect your smartphone to charge and wait 100%.
- In the Health section, look at the Calculated Capacity parameter.
- Compare it to the factory value of 4100 mAh.
💡 Tip: For an accurate test, use AccuBattery for at least 3 days.The app is calibrated to your charging habits.
☑️ Preparation for battery test
4. Visual examination: how to determine bloating
Physical wear and tear of the battery is often accompanied by bloating, which is an increase in its volume due to gas formation, and on the Redmi 4X, this is manifested by the following symptoms:
- 📱 The screen or back cover has been raised (the gap between the case and the glass);
- 🔄 The smartphone is not on the table, it is swaying;
- 🔊 The display flakes off at the edges (seen in the light);
- 🔋 When pressed on the back cover, a crunch or creaking can be heard.
How to check without disassembly:
- Place the Redmi 4X on a flat surface (like a table).
- You can easily tap the corners of the screen. If the battery is swollen, you'll see a backlash.
- Light the flashlight on the side at the junction of the screen and the body, a gap of more than 0.5 mm is a sign of bloating.
⚠️ Attention: A bloated battery is dangerous! It can burst or ignite if you overheat. If you detect a deformity, immediately turn off your smartphone and remove the battery (if possible!
What to do if the battery is blown?
5. Discharge test: how to check real working hours
The most reliable way to measure battery wear is by using a controlled discharge, which will show how long a smartphone will last on a single charge in real-world conditions.
How to run the test:
- Charge Redmi 4X to 100% and disconnect from the network.
- Activate Flight Mode (to eliminate network impact).
- Set the screen brightness to 50%.
- Run the video on YouTube (offline) or turn it on 3D-rendering CPU Throttling Test (for loading).
- Set the time to full discharge.
Normal results for the Redmi 4X:
| Test conditions | Operating time (new battery) | Operating time (wear-out battery) |
|---|---|---|
| Video (YouTube, 50% brightness) | 10-12 hours | 3-5 hours |
| 3D-rendering (maximum load) | 4-5 hours | 1-2 hours |
| Standby mode (Wi-Fi enabled) | 2-3 days | 10-15 hours |
💡 Tip: If the smartphone turns off at 20-30%, it is a sign of severe wear of the power controller or improper calibration. Try resetting the battery settings through Recovery (see next section).
6.Reset battery data via Recovery
Sometimes MIUI incorrectly displays the charge level due to a failure in the batterystats.bin file. This leads to sudden shutdowns or a "jumping" percentage.
How to do this:
- Turn off the Redmi 4X.
- Press the Power button + Volume up to enter Recovery.
- Choose Wipe & Reset → Wipe Cache.
- Confirm the action and restart the smartphone.
After discharge:
- 🔄 Completely discharge the phone before turning off.
- 🔌 Charge up to 100% without interruptions (preferably the original RAM).
- 📱 Repeat the cycle 2-3 times for calibration.
⚠️ Warning: If the problem persists after the reset, it's not the software, it's the physical wear and tear of the battery.
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Resetting through Recovery doesn't restore battery capacity, it only corrects charge display errors, and if the battery is worn out, this method won't help.
7. Disassembly and visual inspection of the battery
If all the software methods have shown that the battery is in critical condition, then the last step is disassembly, which is an extreme measure, but it allows you to accurately assess the physical condition of the battery.
What you need:
- 🔧 Plastic blade or mediator;
- 🔩 Cross screwdriver (for screws under the cover);
- 🧲 Suction (to remove the screen, if required);
- 🔥 Fryer (for softening glue).
Step-by-step:
- Turn off your smartphone and remove the tray for SIM-map.
- Heat the back cover with a hair dryer (temperature ~60 ° C) around the perimeter for 2-3 minutes.
- Carefully tuck the lid with a plastic spatula, starting at the corner next to the USB-C connector.
- Unscrew 10 screws that fix the metal plate.
- Disconnect the battery plume (it is under black insulation).
- Examine the battery for: Bloating (normal thickness - ~ 4 mm); Electrolyte darts (white or green coating); Contact damage.
📌 Important: If you're not sure about your skills, you should contact a service center.
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Before disassembly, take a picture of the location of screws and plumes - this will help to properly assemble the smartphone back.