What Causes Corrosion on Automobile Batteries?

Basics

All parts of the electrical system in an automobile rely on the battery to provide the power to run the systems. Because batteries are made of lead and contain acid, the combination can be very corrosive if not maintained properly. A car battery is an electrochemical piece of equipment that converts chemicals into energy and sends the current through the wires attached to the battery leads. Most standard batteries provide twelve volts of power, which are fired by six cells, each of which produces two volts. In addition to the acid in each cell, there are negative and positive plates made of lead that balance the charge and carry the current through the battery. The battery case that holds all the pieces together is made from heavy-duty plastics. A maintenance-free battery is made of heavy-duty parts throughout the battery and is housed in a closed case.

Corrosion

Corrosion can be caused by a number of different factors. Older batteries that required water to be added were open to many more environmental influences, such as weather and repeated movement, causing the acid to bubble up onto the surface and corrode the metal posts on which the cables are attached. New batteries are closed and do not have any special maintenance schedule. Oxidation in the form of white and green stiff matter around the battery terminals is more common than acid corrosion. New batteries either work or they don't, so there is little room for error that could lead to corrosion. Corrosion on a modern battery is a sign of some problem. Acid may bubble up if there is a hairline crack in the battery. Loose terminals also can create corrosion.

Cleaning

Any signs of acid corrosion on automobile batteries are signals that the battery is damaged and may need to be replaced soon. In addition to not starting properly, an inefficient battery can create problems with the onboard computer system and other electrical components. Keep the battery clean to avoid oxidation build-up. Wear gloves and other protective gear such as goggles to prevent any of the acid from touching your skin. Use a mixture of baking soda and water to scrub off the corrosion and rinse with clear water. Remove the battery cables and scrub the posts. Use a narrow brush to clean inside the connecting cables before reattaching them to the posts.

Resources

• More battery information