Water loss in valve regulated batteries

Water loss in a valve regulated lead acid battery (VRLA) due to inefficient oxygen recombination, corrosion of the positive grid and water permeation through the battery housing were measured as a function of the electrolyte condition from a flooded state to a starved state. In starved electrolyte condition, the rate of measured water loss was found to be consistent with prediction based on weight loss. However, in flooded electrolyte conditions, the rate of water loss determined by weight loss is much higher than that calculated from vented gas measurements. The rate of water loss from the battery decreases as the battery transforms from flooded state to starved state. Because of this change in the electrolyte condition, which is inherent to VRLA battery technology, life estimates based on water loss is not a straightforward calculation.