The battery electrolyte plays a key role in the ability of the battery to store charge. The battery converts the chemical energy into electrical energy through chemical reactions. When the battery is fully charged, the electrolyte is made up of 35% sulfuric acid and 65% distilled water. The electrodes are made of lead oxide,. During charging, the electrical current that reverses the reactions that occurred during discharge causes the water in the electrolyte to undergo electrolysis. This is a situation where the water decomposes into it's original. When adding battery water, you should never add tap water or bottled water. Tap water contains minerals that will react with the sulfuric acid in the battery. When this reaction takes place, it will. As stated earlier, under normal circumstances, the battery will never lose sulfuric acidbut will only lose water. That means the levels of sulfuric acid either free or in the plates remain the. Though we have said under no circumstances should you add acid to the battery, there are some exceptions when you can add acid to the battery. However, you should never add acid that is concentrated but you.