How to check the battery capacity on Android: from factory values ​​to current wear

Battery capacity is a key parameter that determines how long your smartphone will work without recharging. Over time, the battery degrades: after 300–500 charging cycles, its actual capacity may decrease by 20–30%. But how do you know how worn out your battery is right now? Manufacturers rarely show this information in the settings, and the inscription “4000 mAh” on the box is factory valueand not the current state.

In this article you will find 7 working methods checking battery capacity on Android - from simple (via the phone menu) to advanced (using ADB and the engineering menu). We will also look at how to distinguish real capacity from calculated, why the data may differ in different applications, and what to do if the battery has lost more than 50% of its original capacity. All methods have been tested on devices with Android 10–14 and are relevant for smartphones Samsung, Xiaomi, Realme, Oppo, Google Pixel and other brands.

1. Checking through Android settings (without applications)

Some manufacturers add hidden battery diagnostic tools to the firmware. This data is not always accurate, but gives a general idea of wear.

On devices Samsung (from One UI 4.0+):

1. Open Settings → Device care → Battery.
2. Tap three dots (⋮) in the upper right corner and select Settings.
3. Find the item Battery status —the wear percentage or current capacity can be displayed here.

At Xiaomi/Redmi/Poco (MIUI 12–14):

• 🔋 Go to Settings → Battery and performance → Battery status.
• 📊 If the item is not there, enter the query “battery status».
• ⚠️ In the settings search (for example, Redmi Note 10 Pro) this function is hidden and requires activation via ##4636##.

⚠️ Attention: Built-in tools often show calculatedrather than actual data. For example, Samsung may write “Good condition” even with a loss of 20% of capacity. For an accurate diagnosis, use the methods from the following. sections.

2. Codes for the engineering menu (USSD and service commands)

Manufacturers hide diagnostic data behind special codes. These commands do not work on all devices, but can provide accurate information about the battery.

The most common codes:

• 📱 ##4636## - universal code for Android. After entering, select Battery information. Look for the lines level (current charge), scale (maximum value) and health (status).
• 🔋 *#0228# —works on Samsung. Shows voltage, temperature and calculated capacity in mAh.
• 🛠️ ##36446337## - engineering menu for MTK processors (device Xiaomi, Realme, Tecno). Go to Battery Information.

How to enter codes:

1. Open the application Phone.
2. Enter the code as a number to call.
3. On some devices you need press the call button.

⚠️ Attention: Not all codes work on new versions of Android (12+). If after entering nothing happens, it means that the manufacturer has blocked access. Also do not change parameters in the engineering menu without understanding the consequences - this may lead to system failure.

What do the values in the engineering menu mean?

In the menu ##4636## pay attention on:

- health: Good —the battery is normal; Unknown or Dead —critical wear.

- voltage: normal value is 3.7–4.2 V. If below 3.5 V at 100% charge, the battery has degraded.

- temperature: above 40°C when charging is a sign of wear or malfunction of the controller.

3. Applications for battery diagnostics (TOP-5 from the play market)

If the built-in tools do not show the capacity, use third-party applications. We tested dozens of utilities and selected those that provide the most accurate data (compared with the readings ADB and multimeter).

Application	Accuracy	Features	Link
AccuBattery	⭐⭐⭐⭐	Shows wear, temperature, discharge rate. Requires calibration (2-3 charging cycles).	Play Market
Battery Guru	⭐⭐⭐	Displays capacity in mAh, but sometimes overestimates the values ​​by 5-10%.	Play Market
CPU-Z	⭐⭐	Shows only voltage and temperature, but not capacity.	Play Market
3C Battery Monitor	⭐⭐⭐⭐⭐	The most accurate application (accuracy ±2%). Works with root and without it.	Play Market
AIDA64	⭐⭐⭐	Shows the factory capacity, but not the current one. Useful for comparison.	Play Market

How to use AccuBattery (step by step instructions):

Download the application and allow access to battery statistics|Charge the phone to 100% and wait for the calibration notification|Discharge to 15-20% without recharging|Repeat the cycle 2-3 times for accurate data|Check the tab Health —the current capacity in mAh will be here

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Important: applications without rootaccess may show calculated data based on voltage and discharge time. For maximum accuracy use methods with ADB (section 4).

4. Checking via ADB (for advanced users)

ADB (Android Debug Bridge) is a tool from Googlethat allows you to obtain low-level information about the system, including the actual battery capacity. The method works on all devices, but requires connection to a computer.

What you will need:

• 🖥️ Computer with Windows/macOS/Linux.
• 📱 USB cable (preferably original).
• 🔧 Installed drivers ADB i Fastboot.
• 🔄 Enabled USB debugging on the phone.

Instructions:

1. Activate Developer mode: go to Settings → About phone and tap 7 times on the build number.
2. Go back to Settings → System → For developers and enable USB debugging.
3. Connect your phone to the PC and confirm trust in the computer.
4. Open the command line (cmd) and enter:

adb shell
dumpsys battery

In the output, find the lines:

• capacity —current charge in percent.
• charge_counter — real capacity in μAh (divide by 1000 to get mAh).
• health —battery condition (2 = good, 3 = wear).

adb shell
cat /sys/class/power_supply/battery/charge_full

This command displays maximum capacity in mAh (divide by 1000 for mAh).-->

⚠️ Attention: On On some devices (for example, Huawei c EMUI 12+) access to charge_counter is blocked. In this case, use applications with root-access or the method from section 5.

5. How to find the factory capacity of the battery (for comparison)

To assess wear, you need to know original capacity the battery. This data can be found in several ways:

Method 1: On the box or in the documentation

• 📦 Look at the sticker on the original box - the capacity is usually indicated there (for example, "5000 mAh»).
• 📄 In the instructions or on the manufacturer's website in the characteristics of the model.

Method 2: through the app AIDA64

1. Install AIDA64 from Play Market.
2. Go to section Battery.
3. Find the line Capacity by design —this is the factory value.

Method 3: By battery model

• 🔍 Remove the back cover (if possible) and look at the markings on the battery.
• 🌍 Enter the model number (for example, EB-BG975ABY for Samsung Galaxy S21) in a search engine - you will find technical specifications.

Example of wear calculation:

If the factory capacity is 4500 mAh, and the current one (by ADB or AccuBattery) — 3600 mAh, then the wear will be:

(4500 - 3600) / 4500 × 100% = 20%

6. Physical check (multimeter and disassembly)

This is the most accurate, but also the most difficult method. Suitable if you are ready to disassemble the phone or the battery is removable (as in older models). data-i="203">or Samsung Galaxy J or Xiaomi Redmi 4).

What you will need:

• 🔧 A set of screwdrivers (for disassembling the phone).
• 📊 Multimeter with constant voltage (DC) measurement mode.
• 🔋 Charger with a known current (for example, 1 A or 2 A).

Step-by-step guide:

1. Disassemble the phone and remove the battery (on non-removable batteries, find the contacts + and – on the board).
2. Connect the multimeter to the battery contacts in voltage measurement mode (range 20 V).
3. Completely discharge the battery (to 3.0–3.2 V).
4. Connect the charger with with a known current (for example, 1 A) and note the time of full charging up to 4.2 V.
5. Calculate the capacity using the formula:

Capacity (mAh) = Charging current (mA) × Charging time (hours)

Example: if charging took 4 hours with a current of 1000 mA, then the capacity is ≈ 4000 mAh.

⚠️ Attention: Disassembling the phone void the warranty and can lead to damage to the cables or battery. If you do not have experience, entrust the inspection to a service center. Also, do not discharge lithium batteries below 2.8 V - this may damage them.

7. What to do if the battery capacity has greatly decreased?

If the test shows wear of more than 30%, there are several ways to extend the life of the battery or return to its original capacity.

Recovery methods:

• 🔄 Battery calibration: Completely discharge the phone before turning it off, then charge it to 100% without interruption. Repeat 2-3 times. This resets controller errors.
• ⚡ Battery replacement: The best option for wear >40%. The cost of replacement is from 1000 to 5000 ₽ depending on the model.
• ❄️ Cooling: Avoid overheating (do not play heavy games while charging, do not leave the phone in the sun).
• 🔌 Proper charging: Keep the charge in the range of 20–80%, avoid complete discharges.

When replacement is exactly needed:

• The phone turns off at 20–30% charge.
• The battery is swollen (visible by the raised screen or warping of the case).
• The operating time has been reduced by 2+ times compared to the new state.

Is it possible to restore the battery capacity without replacement?

Partially - yes. Methods such as “training” the battery (discharge-charge cycles) or using special chargers give a temporary effect (increasing capacity by 5–10%). However lithium polymer batteries they degrade irreversibly. The only radical way is replacement.

FAQ: Frequently asked questions about Android battery capacity

🔋 Why do applications show different battery capacities?

Applications without root-access estimate capacity using indirect data (discharge time, voltage), so the error can reach 10–15%. The most accurate methods are ADB and physical testing with a multimeter.

⚡ Is it possible to find out the battery capacity without charging the phone?

Yes, but only if the battery has at least a 10-15% charge. Methods through ADB or the engineering menu also work on a partially discharged phone. A physical test with a multimeter requires a minimum voltage (from 3.0 V).

📉 What does “battery status: unknown” mean in the engineering menu?

This means that the battery controller cannot determine its health. Reasons: firmware failure, non-original battery or critical wear. In the latter case, the battery needs to be replaced.

🔄 How often should you check the battery capacity?

Optimal - once every 3-6 months. If the phone is used intensively (games, video shooting), check it more often. Diagnostics is also required after purchasing a used device.

🛠️ Is it possible to check the battery capacity with the phone turned off?

No, all software methods require the device to be turned on. The only way is to physically check with a multimeter on the removed battery.