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The contribution presents impedance spectra of enhanced flooded batteries (EFBs) with reference electrodes for micro-hybrid applications. Batteries of different manufacturers are compared, also with respect to the temperature-dependency of their impedance spectra. Spectra fitting to suitable electrochemical equivalent circuits (EECs) allows a more thorough understanding of the physicochemical processes in these lead-acid batteries.

Journal of the Electrochemical Society : JES 163(6), A995-A1000 (2016). doi:10.1149/2.0861606jes, Published by Electrochemical Soc., Pennington, NJ

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 the first part, the focus was put on inductive semicircles, while in this second part, concentration limitation and its appearance in impedance spectra is investigated.

Many battery simulation models, but also electrochemical interpretations are based on impedance spectroscopy. However, the impedance of a battery is influenced by various factors, e.g. in the case of a lead–acid battery: state of charge (SOC), charging or discharging, superimposed dc current, short-term history or homogeneity of the electrolyte. This paper analyses the impact of those factors on impedance spectra of lead–acid batteries. The results show that very detailed information about the conditions during the measurement is crucial for the correct interpretation of a spectrum.

SLI lead-acid batteries are still the most commonly used technology in automotive applications around the world. Despite its relatively low gravimetric and volumetric energy density in comparison with other battery solutions it is still installed in the newest micro-hybrid and conventional cars due to its low cost. To facilitate the design of multi-physical systems as complex as modern automobiles, it is critical to have a precise battery aging model that incorporates various operation conditions. This paper presents an aging model that provides crucial information about state of health of SLI battery during lifetime for any conditions like climate, driving style, charging strategy or different battery management approaches. Described model is based both on empirical and physico-chemical solutions and can be calibrated to simulate any SLI lead-acid battery without design limitations.