A. Janse van Rensburg, G. van Schoor, and P. A. van Vuuren, “Active Surface Area Approximation in a Lead-Acid Cell for Optimal Performance in Renewable Energy Systems,” in 19th IFAC World Congress, 2014, vol. 19, no. 1, pp. 9450–9455.

Operating modes that cause irreversible sulphation (IS) in a lead-acid battery were investigated using a multi-scale electrochemical model. Experimental data from a valve-regulated lead-acid battery with an immobile electrolyte were used in a novel concentration-based method for electromotive force (EMF) characterization. The EMF curve was used for model calibration during parametric analysis of the multi-scale model. Variance-based sensitivity analysis confirmed that the parameters for electrode kinetics havethe most significant effect on the simulated voltage. After verification and experimental validation of the multi-scale model, it was used to simulate partial state-of-charge (SOC) operation. It was found that the available active surface area suffers irreversible decreases due to minor errors in SOC indication. Additionally, the internal resistance during the initial voltage drop increases from one discharge to the next. It was concluded that IS cannot be prevented satisfactorily using SOC information because SOC is not indicative of a specific damage mechanism.

Supervisors: Prof George van Schoor, Dr. KR Uren

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