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In this paper a new model-based approach is used to optimize the charging current of lead acid batteries for use in hybrid electric. The used model is a dynamical nonlinear model and so steepest descent, as a nonlinear optimization technique, is used to design the desired current profile. | ISSN:2249-5789 Amin Rezaei Pish Robat et al, International Journal of Computer Science & Communication Networks,Vol 2(1), 117-122 Optimization of Charging Current and SOH Estimation for Lead Acid Batteries Amin Rezaei Pish Robat Faculty of Engineering, University of Bonab, Iran E-mail:aminrpr@yahoo.com Abstract In this paper a new model-based approach is used to optimize the charging current of lead acid batteries for use in hybrid electric. The used model is a dynamical nonlinear model and so steepest descent, as a nonlinear optimization technique, is used to design the desired current profile. To verify the results, Unscented Kalman Filter is used to estimate battery capacity as a criterion of the state of health of the battery. Simulation results show that in comparison with multi level charging current, the proposed approach improves the state of health of the battery, up to 2.5% in the first 100 charge/discharge cycle. 1. Introduction In recent years, batteries play an important role in many fields, such as portable equipments, hybrid electric vehicles (HEVs), etc. Battery life is one of major factors presently limiting the realization of economically viable HEVs [1]. Different charging methods exist in order to increase battery lifetime and reduce the charging time. The simplest charging method is constant current charging in which constant current is used to charge the series batteries. However battery over charging will result in the degradation of battery life and small charging current will prolong the charging time. To overcome this problem, two step charging method (CC-CV) is used, which combines the constant current and constant voltage charging. In the first stage of charging, the batteries are charged by constant current until the battery voltage reaches a preset value and in the second stage, a constant voltage is applied for battery charging [1]. CC-CV is still not suitable for rapid charging since constant voltage charging seriously extends the
