The actual capacity of a battery has always been one of the most important factors for users. After XTAR introduced the 1.5V 4150mWh lithium battery, we have received questions from users about how to test its capacity by themselves. This post will go through how to test the actual capacity of the XTAR AA 4150mWh battery as well as the elements that affect capacity measurement.

Test with Battery Capacity Grading System or Electronic Load

Discharge the battery with the professional capacity grading system or electronic load. This measurement method is the best and most precise. Set the constant discharge current you want and the cut-off voltage on the grading system, start to discharge, and record the discharge time. Then calculate the battery capacity with the formula :

Q=I*T
Here Q means the quantity of electric charge passing through the battery, i.e. capacity. I means discharging current, and T means discharging time. The result is expressed in ampere-hours (Ah) or milliampere-hours (mAh).

Test with Coulomb Counting Method

In this method, you need a resistor and a multimeter. By placing the resistor with known resistance values across the battery terminals, the current is limited and begins to flow. Recording discharging current over time, and you can integrate to calculate the discharged capacity. By measuring the discharge current and time, you can calculate the battery capacity with the formula:

 Q = I*T

The three parameters in this formula have the same meanings as the parameters mentioned above. The battery’s capacity is equal to the quantity of electric charge passing through the battery.

The XTAR Lab uses a high-precision battery capacity grading system to test the real capacity of the 1.5V AA 4150mWh lithium battery. Considering the user may not have the equipment, the electronic load and resistor can also be used in capacity test. The operation of electronic load is similar to battery capacity grading system. You need to set parameters for electronic load to discharge batteries. Using a resistor for capacity testing is easy, but the test results may have big deviations. So it is recommended to use electronic load or battery capacity grading system for testing.

In order to improve the result accuracy, it is advisable to have triple tests or more and take the average. However, during testing, there are also various factors that can affect the test results.

What You Should Know in Capacity Test

Cut-off Voltage Setting 

The cut-off voltage should be set below 0.8V. The XTAR 1.5V 4150mWh AA lithium battery still have some capacity at about 1.1V. Setting the cut-off voltage too high would prematurely stop the discharge at this point, resulting in a lower capacity measurement and inaccurate test results.

Discharge Current Settings

The XTAR 4150mWh AA lithium battery using a 3.6V cell, with a built-in voltage step-down chip to output voltage 1.5V. So, there is energy loss. With different discharging current, there is a deviation in the conversion efficiency, it is recommended to set discharging current of 0.3-0.5A.

Battery Saturation

The saturation of the charge is closely related to the discharged capacity, so make sure the battery is fully charged before testing. It is recommended to use chargers such as XTAR LC4, LC8, L8, L4 and BC4. These chargers have lower cut-off charging currents, which lead to a higher charging saturation.

Other Factors

The capacity of the battery will also be impacted by the discharger’s current deviation, integration deviation, cut-off voltage, battery saturation, and operating room temperature. It is advised to test more than twice and make comparison when you doubt the test result.

Summary

Testing the actual capacity of 1.5V 4150mWh lithium battery requires attention to detail and consideration of various factors. By following the correct test method and considering the above factors, you will be able to obtain accurate capacity measurements and ensure reliable equipment performance.