(457a) Electrical Characterization of Lead-Acid Battery at Load for Hev Applications

Lead-acid batteries have been widely used as secondary batteries for more than a hundred years. For cost consideration, it is still a good resource for fast starting of cold vehicles, for recharging from either a stop-start braking system, or for a charge from the engine itself, which consumes battery energy or stores electricity back into chemical energy. Battery modeling is a key issue for different battery applications. It is necessary to develop a reliable and easy-to-parameterize battery model. In this work, the impedance technique is applied to dynamic modeling of battery behavior and diagnosis of quantities like actual capacity, state of charge (SoC) and state-of-health (SoH). Interpretation of the test results and proper modeling requires that the experimental setup allows some idealization like separating between working electrodes with reference electrodes or maintaining constant concentrations of reactants at the interface. The measurement and interpretation of the impedance of lead-acid batteries is further discussed, especially on nonlinearity, voltage drift, stability, half-cell measurements, model structure, and parameter extraction from the impedance data. This initial work focuses on the methods and procedures for testing lead-acid batteries at load and development of a reliable circuit model for predicting battery performance, which provides an opportunity to simulate a sophisticated lead-acid battery power system for HEV applications in a real time environment.