Abstract The paper presents an equivalent circuit based simulation model for the static and dynamic behavior of lithium-ion battery systems and explains the different steps of the theoretical and experimental modeling process. The equivalent circuit based model describes the voltage-current characteristic, the state of charge behavior and the occurring losses of the battery system. A parameter identification method based on three characteristic experiments, a cycle test, an open circuit voltage test and pulse tests, is introduced. The model parameters are estimated employing a nonlinear optimization method. Furthermore, the experimental test bed for investigation of lithium-ion battery systems is described. The battery model approach is demonstrated and validated for a commercial 5 kWh lithium-ion battery system, including the model validation for test profiles and emulated battery charging and discharging profiles of a real photovoltaic home storage application. The comparison of measured and simulated voltage profiles indicates an excellent performance of the battery model.