The concentration of sulfuric acid in the battery acid is another critical factor. For example, metal impurities such as iron, copper, and nickel can cause self. The term battery acid used in batteries usually refers to sulphuric acid for filling lead acid battery with water. Sulfuric or Sulphuric acid is diluted with chemically clean & pure water (de-mineralized water) to. Most lead-acid batteries have an electrolyte solution made up of water and sulfuric acid. This highly corrosive electrolyte is essential for generating electrical energy in vehicles and other. H₂SO₄ is best stored out of direct sunlight. Tank capacities range from 35 to 100,000 gallons.