Will the specific gravity of the electrolyte decreases as the battery is discharged?

Yes, the specific gravity of the electrolyte typically decreases as a lead-acid battery is discharged. This is because the active material in the battery converts lead dioxide and sponge lead into lead sulfate, which reduces the concentration of sulfuric acid in the electrolyte. As a result, the specific gravity, which measures the density of the electrolyte solution, decreases as the battery undergoes discharge.