We’ve all been there before. You turn the key on your car and…nothing. Not even the telltale clicking of the starter solenoid. Often, corrosion on the battery terminals is preventing a good connection. Here are some simple ways to clean and prevent car battery corrosion.
Why do car battery terminals corrode?
A battery is just one big chemical reaction, and the white, scaly deposits on the posts are simply one of the byproducts.
A typical car battery is made up of individual cells, with each housing alternating plates of lead and lead coated with lead dioxide submerged in a sulfuric acid solution. This causes a chemical reaction that releases electrons, providing the juice that spins the starter motor, powers the radio and keeps the lights on, among other functions.
Sometimes, especially on cheap batteries, the seal around the post allows sulfate in the battery to escape and react with lead in the post, producing white, flaky deposits. If bad enough, they’ll interfere with the battery connections and prevent the flow of electricity, leaving you stranded.
How to clean car battery corrosion
Fortunately, this is one of the easiest areas of your vehicle to maintain. Here are a few simple methods of cleaning corrosion from car battery terminals.
Make sure to wear safety glasses and protective gloves since sulfuric acid can be dangerous.
1. Use water and baking soda
Water and baking soda is a tried-and-true cleaning method.
Mix them to create a concoction the consistency of pancake batter and smear it on the terminals. The mixture will slowly eat away the corrosion.
Although it works, it’s a mess. I remember my dad performing this trick on my sister’s Ford Pinto back in the 1980s. Incidentally, my dad rarely swore, but my vocabulary expanded a little every time he had to work on that poor excuse for a car.
2. Pour out a can of cola
You can accomplish the same effect using any brand of cola. Its slight acidity will slowly dissolve battery terminal corrosion. Pour some on the terminals, let it sit for several minutes and then wipe clean.
3. Use a battery terminal brush
Why waste a good can of sugary goodness when you can use a battery terminal cleaning brush?
I have about three of them scattered around the garage. One reason I like them is because they’re like me – cheap, but effective.
Simply disconnect the battery, starting with the negative terminal. Use the brush to loosen and remove deposits and corrosion from the terminals and connectors.
How to prevent battery terminal corrosion
I like preventing battery terminal corrosion even better than cleaning it.
Apply battery-terminal grease to the terminals to help prevent corrosion. It’s available at any auto parts store and usually comes in a little ketchup-like packet.
Another great option is AMSOIL Heavy-Duty Metal Protector. It creates a protective coating on terminals that wards off corrosion. Plus, you can use it as a vehicle undercoating to guard against rust.
Whatever your method, pop the hood periodically and give the battery terminals a good cleaning as needed. Living where sub-zero cold is common, I clean my battery terminals every fall regardless how they look to ensure I’m not met with a dead engine when I turn the key on a cold morning.
Updated. Originally published March 27, 2017.