Cell resistance, or effective series resistance (ESR), is a consolidated parameter that represents all elements that are resistive at high frequency. These primarily include ohmic resistance of the cell current collector and packaging components. Cell ESR contributes to cell losses under charge/discharge cycles and is an important parameter when considering the maximum power output of the cell, typically estimated by the below equation.
The following steps are used to measure cell ESR. It's easiest to perform these steps with a high sampling rate voltage measurement device (>5kHz). A current supply or load with a discrete on/off switch is suitable to support the fast transition times requires.
Shown below is the expected waveform from the instruction set.
The below equations are used to measure the cell ESR. The final ESR is reported as the average of the two resistance measurements.