Principles of Function, Construction and Application of Valve Regulated Lead-Acid Batteries

Abstract

One of these parasitic reactions is the electrolytic decomposition of water (hydrolysis) in the electrolyte, thereby developing the gases oxygen and hydrogen. The decomposition-potential of water (1.23 volts at 25°C) is far below the equilibrium potential of a lead-acid battery (ca. 2.1 volts). The rate of this reaction rises exponentially with the potential (by a factor 10 for every 0.2 volts in conventional batteries). During the charging of a battery, more and more water is decomposed with rising state of charge and potential.