The only electrolyte that can be used in a lead-acid battery is sulfuric acid. Adding anything but water to a battery can instantly damage it, but some substances are worse than others. For example, baking soda can neutralize the sulfuric acid present in a battery's electrolyte solution.
Under normal conditions, sulfuric acid in the electrolyte solution is absorbed into the lead plates as the battery discharges power. It is then released back into the electrolyte solution as the battery charges. The only electrolyte that can be used in a lead-acid battery is sulfuric acid.
A lead-acid battery consists of lead plates, lead oxide, and a sulfuric acid and water solution called electrolyte. The plates are placed in the electrolyte, and when a chemical reaction is initiated, a current flows from the lead oxide to the lead plates. This creates an electrical charge that can be used to power various devices.
Hydrochloric acid, as well as nitric acid, are also strong acids like sulfuric acid. So, why are not they used commercially in lead-acid batteries? HCl and HNO3 can't be used because they both would participate in redox reactions.
Battery electrolyte is the liquid substance found in most car batteries. It's sometimes referred to as battery acid because it's highly acidic. In fact, the battery electrolyte is made from a mixture of water and sulfuric acid.
If your battery electrolyte is low, the only thing you should ever add is straight water. There are some specific circumstances where sulfuric acid may be added, such as if the battery has tipped over and leaked, but never add anything else. What Does it Mean When Battery Electrolyte is Low?