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While PbA batteries still dominate the market in low voltage applications in contemporary vehicles, there are significant shortcomings associated with them that warrant the exploration of alternative chemistries. The demerits of PbA batteries can be mostly attributed to their low cycle life and fairly rapid health degradation. A promising alternative chemistry to PbA batteries for low voltage automotive applications is the LTO battery. It offers a similar nominal voltage while possessing exceptional life cycle. In this paper, an LTO||NMCbattery module is investigated for 12 V applications. A key aspect of an effective battery monitoring algorithm is development of an electrochemical model which allows the establishment of an understanding of the underlying aging mechanism of the battery as well as potential state of health estimation schemes. Hence, in this work first Padéapproximation is employed to develop a reduced order enhanced single particle model of an LTO||NMCbattery, and subsequently a multi-stage optimization process is introduced to estimate the parameters of the resulting electrochemical model. To this author’s knowledge, this is the first reported instance of these methods being applied to this specific battery chemistry.

Lead-acid (PbA) batteries are one the most prevalent battery chemistries in low voltage automotive applications. In this work, we have developed an equivalent circuit model (ECM) of a 12V PbA battery while preserving the major dynamics of a semi-empirical model we have developed previously. Thereafter, two batteries are aged according to a modified IEC 60095-1 standard and the evolution of ECM parameters investigated. The trend derived from these aging campaigns are used to determine the state of health (SOH) of three either new or aged on the vehicle batteries. The contribution from this approach stems from the fact that the ECM model while being simple is capable of approximating the sum of charge transfer resistances of both electrodes from a short step response. In addition, another SOH estimation technique is developed based on frequency response analysis of a metric dubbed instantaneous dynamic resistance derived from voltage response of the battery during engine cranking. Real world voltage response of the battery during cranking is imitated in the lab and superposed on IEC 60095-1 standard profile, according to which another battery is aged. This data is used to assess the performance of SOH estimation technique.

•A novel method is proposed for developing a semi-empirical model with parameters that are explicitly tied to the underlying physio-chemical processes inside a battery.•Battery terminal voltage is predicted in the semi-empirical model through determination of Ohmic, activation, and concentration over-potentials.•Exchange current and charge transfer resistances of positive and negative electrodes are chosen as indicators of dominant aging mechanisms for a PbA SLI battery.•The feasibility of employment of the model is verified through aging a battery according to a modified IEC60095-1 accelerated aging standard and battery performance is characterized at regular intervals and used to calibrate the model.•Furthermore, charge transfer resistances of negative and positive electrodes for a battery that has aged on the field, were estimated and compared with the trend acquired from the battery aged through the IEC60095-1 accelerated aging standard to further verify the model.