Impedance measurements of both electrodes of a flooded OEM SLI battery at various SOC and with various direct currents have been measured. For each part of the impedance spectra, an electrochemical process is proposed and implemented in a simulation model. By simulation of impedance spectroscopy, spectra of the model are obtained and compared with the measurement. In this first part, the focus is put on inductive semicircles in impedance spectra.