Sensitivity of lumped parameter battery models to constituent parallel-RC element parameterisation error

A sensitivity analysis for a two time-constant Randies´ circuit model to its forming resistor-capacitor elements is presented. The model parameters are identified for a cylindrical lithium-ion iron phosphate cell using the electrochemical impedance spectroscopy technique and a nonlinear least squares approach. Initially, it is shown that the model parameters vary as a function of the battery´s state-of-charge. Then, each model parameter is allowed to vary up to ±50% of its best-fit value. Finally, the significance of each parameter for the calculation of the battery´s average available power (state-of-power) over a specific band of frequency is analysed.