Modern smartphones Samsung Galaxy have powerful hardware and bright screens that consume a significant amount of energy. Over time, users notice that the device, which previously lived quietly until the evening, now requires recharging by lunchtime. This is a sure sign that the chemical resource lithium-ion battery is coming to an end, and its actual capacity has become significantly less than the rated capacity. However, the Android operating system is not always willing to share this data in the standard settings menu, hiding it from the eyes of the average user.
Understanding the real state of the battery is critical for planning a replacement or optimizing the operation of the gadget. Many owners of flagships and budget models Galaxy A and S series are wondering where to find hidden diagnostic tools. In this article, we will analyze all the available methods: from built-in engineering menus to advanced methods using a computer, which will give an accurate answer to the question about the health of your battery.
Using the built-in USSD engineering menu
The fastest way to access diagnostic information on devices Samsung is to use special USSD codes. The engineering menu, often called Service Mode, allows you to see technical parameters without installing third-party software. To start, you need to open a standard telephone dialer and enter the combination *#0228#. After entering the last digit, the menu will open automatically, displaying the current charge, voltage and temperature.
In the window that opens, you will be greeted with a list of parameters, among which there is a line FuelGauge. It is this component that is responsible for monitoring the battery. By pressing the button Quick Start at the bottom of the screen, you will start the calibration process, which will turn off the display for a few seconds. This is normal, as the system recalculates the current voltage readings to correctly display the percentage of charge.
⚠️ Attention: Do not press the button Quick Start too often or when the phone's charge is below 15%. Forcing calibration at low energy levels may result in incorrect percentages being displayed or the device turning off unexpectedly.
Although this menu shows the current status, it does not always display a direct "maximum capacity" number in milliamp-hours (mAh). However, by observing the parameter Voltage and the discharge rate, one can indirectly judge wear. If the voltage drops too quickly under load, the physical wear of the cell is high.
Diagnostics through the secret code Battery Status
Another diagnostic layer available on the shell One UIis the extended battery status menu. It is activated by the code *#9900#, which opens the system log (SysDump). Here you need to scroll down the list to item Battery Status. This section provides more detailed information about the charge cycles and the current state of the power controller.
Unlike the previous menu, here you can find information about the number of recharge cycles, if this function is supported by the specific power controller in your model. A charge cycle is a complete discharge from 100% to 0% and subsequent restoration. Lithium polymer batteries usually retain about 80% of their original capacity after 500-800 such cycles.
An option is also often available in this menu Low Battery Reset. It is useful if the phone behaves strangely: it shows 15% and then suddenly turns off, or it charges to 90% and sits still for hours. Resetting the controller can eliminate software calibration errors, but will not restore a physically worn out battery.
What to do if the code does not work?
Some cellular operators or firmware may block access to USSD codes. In this case, try entering the code through Google's Phone app or a third-party dialer. If this does not help, the method is not available at the software level.
Checking via ADB and computer (The most accurate method)
If Samsung's built-in tools do not provide a complete picture, the tool Android Debug Bridge (ADB)comes to the rescue. This is a console utility from Google that allows you to communicate directly with the operating system. To work, you will need a computer (Windows, macOS or Linux), a USB cable and USB debugging enabled on your smartphone. This method allows you to extract raw data from system files that are hidden from the normal interface.
First of all, you need to activate the hidden developer menu. Go to Settings → About phone → Software information and quickly click 7 times on the item Build number. After the message “Developer mode has been activated” appears, return to the main settings menu, where a new section will appear Developer options. Inside, find and turn on the switch USB debugging.
Connect your smartphone to computer and open a command line (CMD or Terminal) in the folder with ADB installed. Enter the command to check the battery status:
adb shell dumpsys batteryThis command will display a list of parameters including level (current charge), status (charging status) and health (status). However, to find out exactly the capacity, a deeper command is often required, depending on the chipset:
adb shell cat /sys/class/power_supply/battery/capacityOr, to obtain information about the battery design:
adb shell dumpsys batterystats --chargedThe resulting data can be presented as codes or percentages of the calculated capacity. By comparing the current readings with the passport data of your model, you can calculate the degree of degradation. For example, if the phone reports a full charge at a level corresponding to 3000 mAh from the factory 4000 mAh, the wear is 25%.
☑️ Preparing for diagnostics via ADB
Analysis using third-party applications
When you don’t want to tinker with the command line, specialized applications come to the rescue from Google Play Store. apps like CPU-Z, Ampere or AccuBattery can read data from the power controller and interpret it in an understandable form. They are especially useful for tracking wear and tear trends in real time.
The app AccuBattery, for example, does not know the exact capacity of your battery initially. It learns as you use it: you charge your phone, the app measures how much energy has gone into the battery and compares it to the percent change. After several charging cycles, it will give an estimate of the actual capacity (Design Capacity vs Estimated Capacity).
It is important to understand that such applications provide estimates. The accuracy depends on the quality of the calibration of the controller itself inside the phone. If the controller “lies” to the system, then the application will show incorrect numbers. However, this is the best way for the average user to get an idea of battery health without a PC.
| Application | Data Type | Accuracy | Root required |
|---|---|---|---|
| CPU-Z | Specifications | Average | No |
| AccuBattery | Wear rating (mAh) | High (after training) | No |
| Battery Charge Limit | Charging control | High | Yes (for full functionality) |
| 3C Battery Manager | Deep statistics | Very high | Desirable |
Physical inspection and marking battery
The most reliable, but also the most time-consuming way to find out the maximum capacity is to look at the physical markings of the battery itself. In modern smartphones with non-removable batteries, this requires opening the case, which requires special tools. However, if your phone is no longer under warranty or you are planning a replacement, this method will give a 100% accurate answer. Samsung with non-removable batteries this requires opening the case, which voids the warranty and requires special tools. However, if your phone is no longer under warranty or you are planning a replacement, this method will give a 100% accurate answer.
On the front side of the battery there is always information about its type, voltage and capacity. Look for the line where the value is indicated in mAh (milliampere-hour) or Wh (watt-hour). For example, marking 3000 mAh / 11.55 Wh means that the standard capacity is 3000 milliamp-hours. By comparing this figure with the software readings, you can accurately determine the percentage of loss.
⚠️ Attention: Opening the case of a modern smartphone requires heating the adhesive layer and using suction cups. Inexperienced actions can lead to damage to the screen cables, puncture of the battery (which is a fire hazard) or violation of IP68 moisture protection.
If you still decide to open it, pay attention to the swelling. If the battery is swollen and takes up more space than intended, its use becomes dangerous. In this case, the question “how to check the capacity” disappears - the element requires immediate disposal.
To extend the life of the new battery, try not to discharge the phone to zero and do not keep it charged at 100% for too long. The optimal range for energy storage is from 20% to 80%.
The influence of temperature and operating conditions
It is worth remembering that capacity readings may temporarily fluctuate (fluctuate) depending on external conditions. Lithium-ion chemistry is extremely sensitive to temperature. In cold weather, the capacity temporarily drops, the phone may turn off at 20-30%, but after warming up it will show the charge again. This is not degradation, but a physical feature of the reaction.
Conversely, overheating is the main enemy of the battery. Exposing your smartphone to direct sunlight for a long time or using heavy games while charging leads to irreversible destruction of the cathode and anode structure. Under such conditions, the actual capacity drops faster than the calculation cycles predict.
If you notice that the phone quickly discharges only in the cold or, conversely, heats up and sits down when idle, the problem may be not only the wear of the capacity, but also a malfunction of the controller or a software failure. In such cases, resetting the settings or flashing the firmware may help, but they do not cure physical wear and tear.
⚠️ Attention: One UI interfaces and system menus may change depending on the Android version and regional firmware. Locations and code availability may vary. Always check the latest documentation for your specific model.
The safest and fairly accurate method for the average user is to use the AccuBattery application for a week. ADB provides more technical data, but requires a PC.
Frequently asked questions (FAQ)
Is it true that completely discharging to 0% harms a Samsung battery?
Yes, deep discharge is harmful for modern Li-Ion and Li-Pol batteries. The power controller may go into deep sleep, and it will be difficult to charge such a battery with a standard charger. Try to charge the phone at 15-20%.
Is it possible to programmatically increase the battery capacity?
No, programmatically you can only calibrate the percentage display or limit the charge (for example, to 85%) to slow down physical wear. The software is not capable of increasing the physical volume of energy stored in the cell.
Why did the battery hold up worse after updating Android?
In the first 2-3 days after a major system update, the process of indexing files and optimizing applications occurs in the background. This temporarily increases energy consumption. If the problem does not go away after a week, the update may contain a bug.
What does "Bad Battery" mean in the engineering menu?
This is a critical signal that the power controller has detected a battery fault. This could be a critical voltage drop, overheating, or the inability to accept a charge. Battery replacement is required.