A car battery indicator light generally signals a faulty battery, faulty alternator or faulty wiring. One of the easiest repairs is a faulty battery or battery with a bad cell, which means the battery cannot receive a charge.
A faulty alternator often causes issues in addition to a warning light, such as dim lights, a weak or completely dead battery, a smell that resembles burning rubber, or a grinding noise. Faulty wiring occurs when a wire is broken completely or partially, disrupting the flow of electricity.
The battery warning light may also come on as a result of dirt and sediment buildup on the battery terminals. Clean this buildup with a wire brush, petroleum jelly and rags. Pouring a can of soda on the battery terminals also works to neutralize the acid.
When cleaning battery terminals, it is possible for a spark to occur that can result in a burn or explosion. Always disconnect the negative post first and reconnect it last. Remove rings and watches, as well as anything metal, while cleaning terminals. Wear safety goggles, ear protection and gloves to prevent battery acid from touching the skin. Always throw away rags with battery acid on them, and thoroughly clean hands and tools.