Improved OCV measurement method with reduced relaxation time

The open circuit voltage (OCV) of a battery cell is critical in many aspects of the battery management. However, the conventional OCV test methods are time consuming due to the need for a long relaxation period to approach the equilibrium state. In this paper, a rapid OCV test method is proposed to obtain the static OCV by employing two couples of current excitations, with parameters predetermined based on a second order equivalent circuit model (ECM). Due to the current excitations imposed after the SoC variation step, the polarization voltage shows faster convergence speed in comparison to the conventional self-rest method. Furthermore, the accuracy and the rapidity of the proposed method are verified through simulation and experiment results.