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 a comprehensive battery model which consists of electrical, thermal and aging part that provides crucial information about the current state of SLI battery during lifetime for any conditions like climate, driving style, charging strategy or different battery management approaches. The described model is based on empirical, physico-chemical and equivalent circuit solutions and can be calibrated to simulate any SLI lead-acid battery without design limitations. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.019209jes] All rights reserved.