The effects from increasing silver levels in lead acid battery active materials for SLI applications

Surveys indicate that silver levels in refined soft lead are increasing. This refined soft lead is used to prepare the oxide utilized in both the positive and negative active materials of the lead acid battery. High silver levels in the active materials could adversely influence lead acid battery performance. To address this, four silver contamination levels, in both the positive and negative materials, have been studied in flooded automotive lead acid batteries. The silver levels studied were roughly 0, 50, 100 and 450 ppm. Up to 100-ppm silver, there is no adverse effect on battery performance or gassing properties for flooded automotive batteries. At 450 ppm silver the gassing rate is increased; however, the effect diminishes with increasing operating temperature.