Invented in 1859, lead acid batteries are the oldest type of rechargeable battery. The cells in this type of battery produce a high power-to-weight ratio, meaning it produces a lot of energy in a little space. Since these batteries are also low-cost, they are ideal for use in motor vehicles. Although this type of battery is found in all cars, there are dangers involved, so care must be taken.
A lead acid battery is basically a rechargeable device used to store electrical current. The battery is made up of plates creating chambers (or cells), lead and lead oxide. The battery is filled with an electrolyte, which is a substance that contains free ions and is therefore able to conduct electricity. The ions in the electrolyte react with the lead and lead oxide, creating energy.
The electrolyte is a solution of 35 percent sulfuric acid and 65 percent water. This acidic fluid converts the electrical energy into potential chemical energy and then back again. Sulfuric acid is a clear, odorless, viscous chemical. Sulfuric acid is the most-used chemical in industrial applications, but the lead acid battery is the only consumer product that contains this potentially dangerous chemical.
There are several types of lead acid batteries, including the wet cell and the gel cell. In wet cell batteries, often called flooded batteries, the acidic electrolyte is a liquid. These batteries may require water to be added periodically. In the gel cell battery, the electrolyte is suspended with the addition of a silica additive. This stiffens the electrolyte. Although the gel cell battery is more expensive, it is also safer to use. In these batteries, there is a smaller chance of hydrogen gas explosions and of corrosion due to the acid.
Overcharging a battery generates both oxygen and hydrogen gases. The battery is designed to vent excess gases or contain them so they can recombine to form water. However, if excess gas accumulates, it can be dangerous. This combination of gas is highly explosive. If the excess gas is ignited, the resulting explosion is sufficient to burst the outer casing of the battery, injuring any person nearby with the spray of fluid and pieces of shrapnel.
Sulfuric acid is a highly corrosive acid. When it comes in contact with skin, it causes severe, even third-degree, burns. Even a mist of the acid is irritating to the eyes, nose and throat. If sprayed directly in the eyes, blindness can occur. When sulfuric acid mist is breathed in, it irritates the lungs and can even cause pulmonary edema, which is the buildup of excess fluid in the lungs.
When working with your battery, wear safety goggles to protect your eyes. Also, since sulfuric acid eats through clothes, especially cotton clothes--therefore leaving your skin exposed--wear polyester. Polyester is naturally acid-resistant, keeping your skin safe from exposure. Follow manufacturer guidelines on maintenance, and when in doubt, get advice from a professional. Remember, working with a battery means working with corrosive acid, explosive gases and electrical current, all of which can be a recipe for disaster.
