Hydrogen sulfide in VRLA cells

This investigation of hydrogen sulfide (H ₂S) in VRLA cells produced three major results. First, VRLA cells produce significant amounts of H ₂S even at normal float voltages. Second, the lead dioxide in the positive plates absorbs much of this H ₂S. Third, this "H ₂S cycle" in VRLA cells results in an equilibrium concentration level of no more than 1 ppm of H ₂S in the gas space of a typical cell. The data further suggests that even this low amount may decline over time.