The aim of this research is to examine the effect of alloying elements in positive plate composition of a lead-acid battery on its self-discharge and delivered current density in discharge state performances. To elucidate, a positive and negative lead-acid battery plates of two alloys namely Pb-Ca-Ag and Pb-Sb are investigated through electrochemical measurements in battery solution. Higher delivered current density of Pb-Ca-Ag cell in compare with Pb-Sb cell is observed for 25 days of 33 measurement days. The evolution of couple potential for both cases shows that the Pb-Ca-Ag cell potential achieves a value in the potential range of water stability after 25 days while in case of Pb-Sb cell, it remains well beyond the water stability potential domain for 33 days of measurements. Further investigations demonstrate that Pb-Sb cell current density is mainly caused by Pb oxidation reaction on negative plate while both anodic and cathodic polarizations (mixed polarization) are responsible in the case of Pb-Ca-Ag cell. (C) 2011 Elsevier B.V. All rights reserved.