The internal resistance of a battery can be measured from either AC or DC test. In a DC test which is also known as DCIR Test or simply DCIR, the battery is subjected into a very low discharge current namely I1 while its voltage becomes stable at let say V1. Then a sudden change in input current is imposed such that the current suddenly changes to I2 in a short time with the voltage of V2. Then the internal resistance is:
Ri = (V2-V1)/(I1-I2)
There are different values in defferent standards for I1, and I2. Therefore, you have to decide which standard you are following. For example, IEC 61960 indicates that I1=C5 for 10 seconds and I2=1C for 1 second. You can find other values from different standards.
Battery and Energy Generators Research Lab, offers the followind devices for performing DCIR test.


Neware 5V-12A
  • Neware 5V-12Amps battery tester and cycler
  • is capable to obtain DCIR of any cell or battery with voltage less than 5V and the capacity up to 48Ah. The device is equipped with sophisticated software that automatically calculates the internal resistance of the cell according to any standard. The advantage of the device is that it calculates the DCIR of the cell with respect to its SoC by swiping it from 100% to 0% or in any desirable range in between.
    Neware 30V-60A
  • Neware 30V-60Amps battery tester and cycler
  • is the same as the previous one but the voltage can reach up to 30V and the current up to 120A. The fucntionality is the same.
    Smart Charger
  • Smart Charger
  • has the potential to calculate the internal resistance of the cells. The main advantage of this device is that it is able to calculate the internal resistance of individual cells that are connected in series.


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