Self-Discharge Reactions In Lead-Acid Batteries

A theoretical and experimental analysis of the self‐discharge of lead‐acid batteries shows that seven different reactions contribute to the process. The rate of each has been determined. It is shown that positive plate self‐discharge is due primarily to a reaction between and grid metal. The rate of this reaction decreases with increasing acid concentration because of the passivating action of the layers formed. The passivating action is decreased by the presence of antimony in the grid, producing pores in the layers and providing further access of the electrolyte to the grid. At low acid gravities antimony compounds become almost insoluble and can act as passivators decreasing the reaction between grid metal and . Other self‐discharge reactions in positive plates are the decomposition of water by with evolution of oxygen and the oxidation of separator material in contact with . Oxidation of hydrogen, coming from the negative plates, occurs at immeasurably small rates.