How to Test Battery Capacity?

how to check battery capacity

by Alex Gustman

Updated: August 13, 2021

The operation of the smartphone leads to the gradual wear of all components, including the battery. This is a natural and irreversible process which results in the reduction of the maximum amount of stored energy. This article will let you know how to check the real battery capacity in a smartphone, tablet and other mobile electronics. Why do batteries wear out and how to extend the service life of the power source.

How to check the real battery capacity

There are two most simple and affordable ways:

  • via a USB tester
  • Using the Accu Battery or 3C Battery Manager app

The version with a USB tester works based on the principle of measuring the energy stored by the battery during charging. To do this, you will need to buy an appropriate measuring device, then measure and compare the capacity indicators. The average price of the most affordable tester in Chinese stores is 3 USD.

The Accu Battery and 3C Battery Manager app collect statistics on battery consumption and charging and then calculate the actual battery capacity. The whole process is automated and does not require the purchase of measuring devices. At the same time, this method does not differ in sufficient accuracy. In particular, if the manufacturer did not specify the exact capacity of the battery.

How to measure the capacity through a USB tester

Before testing, buy your preferred USB tester. Any model that displays the value of capacity is suitable for measurement. The method is also relevant for measuring the battery capacity in wireless headphones, universal mobile batteries, fitness bracelets and smart watches.


  1. Discharge the battery to 5-15%. It is advisable to close the open applications, switch the device to the air mode, it is even better to turn off the power.
  2. Connect the USB tester to a network charger. If the charger does not support disconnecting the cable, use the UMB (Power Bank) . For accurate measurement, it is important to use a charger with a power of not more than 5 W. Otherwise, the collected data will not be accurate.
  3. Make sure that the USB tester values are reset. Otherwise, reset the data. This usually requires holding down a single button and holding it for 5-7 seconds until a reset occurs.
  4. Next, connect the power cable to the tester, and install the cable in the charging port of the mobile device.
  5. Connect the charger to the power supply if a power adapter is used.
  6. As soon as charging starts, the USB tester will display the main parameters: the supplied voltage and current, as well as the charging time and the capacity stored by the battery.
  7. Wait until the battery is charged to 99-100%, then turn off the power to the smartphone. If you previously turned on the air mode or turned off the smartphone, then deactivate the air mode or turn on the device and use it.
  8. Compare the capacity value on the tester with the battery capacity specified in the characteristics of the smartphone. The information is available on the box and the official website of the manufacturer. Make an adjustment for the remaining battery capacity before testing.
usb tester

For example, a smartphone has a 4000 mAh battery. The measurement showed 3200 mAh with a 5 % balance before testing. Therefore, the real capacity is in the range of 3100-3350 mAh, and the loss of battery capacity during operation is about 20 %. It is worth writing off 3-5% for measurement errors and losses that occur during transmission and conversion.

To improve the accuracy of the measurement, it is advisable to measure the battery capacity after buying a mobile device. And then compare it with the values obtained in a year or two or another period.

How to test battery capacity in Accu Battery and 3C Battery Manager apps


  1. Install one or both applications on your smartphone. For Accu Battery, the minimum system version is Android 5.0, and for 3C Battery Manager is Android 4.1.
  2. Launch the application Both applications, when initially used, will ask you to specify the battery capacity for measurement. You can edit the readings if you know the exact battery capacity.
  3. Provide applications with access to the usage history for data analysis.
  4. If the battery is discharged to 20 % or lower, put the device on charging. Otherwise, use the phone, and then connect it to the charger. It is advisable to use a low-power network adapter without fast charging technology.
  5. Wait for the charge to reach 99-100%, and then disconnect the charger.
  6. Information about the battery capacity in the Accu Battery program is located at the very bottom on the Charging tab.

The battery capacity data in the 3C Battery Manager application is located on the Compare tab. To go to the tab, you need to scroll through the available tabs on the home page.


How to test NiMH battery?

By means of a battery charger with measurement of the main parameters of the battery. It is worth paying attention to the chargers manufactured by Opus and La Crosse.

How to test battery reserve capacity?

It is necessary to measure the operating time of the battery under load. To do this, fully charge the battery and then discharge under high load to minimum voltage. And then measure the capacity given by the battery.

How to check battery capacity with multimeter?

You should attach the multimeter probes to the corresponding battery poles. Then measure the battery voltage on the multimeter.

How many mAh is a 12 volt battery?

The battery capacity is affected by the current draw and the size of the battery. The larger the battery and the lower the current draw, the higher the battery capacity.

How many volts is 5000mah?

The voltage value is regulated by the output power and is independent of the capacity. In mobile batteries the voltage is 3.7 volts and in automotive batteries 12 or 24 volts.

How long will a 50ah battery last?

The duration of the operation is influenced by the load. The smaller the load, the higher the run time. At 12 volts you get 600 W without conversion losses.

How do you find the AH of a battery?

Relevant information is indicated on the outside of the battery.

How do you calculate battery Ah?

You must multiply the voltage by the amperage.

How can you tell if your car battery needs replacing?

The battery voltage and the integrity of the case should be checked. If the battery does not hold the required voltage, does not operate at minimum negative temperatures, or the case is damaged, the battery should be replaced. The battery typically lasts for 2 to 5 years.

How do you tell if a battery is good without a tester?

The battery should be checked for proper operation. If the battery does not work or does not work long enough, the battery should be replaced.


The article describes in detail how to check the battery capacity. The USB tester will show the most accurate information by calculating the amount of energy transferred to the device. It is important for mobile applications to specify the exact battery capacity for accurate measurement, otherwise, the statistics collected will not be accurate.

What questions do you have? Leave messages in the comments at the bottom of the article.

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About the author 

Alex Gustman

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