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Battery Terminal Cleaning: How to Fix a Corroded Car Battery


Few things are more disappointing than setting out to drive your car only to find the engine doesn't start. Hundreds of moving parts have to be in working order to make a car run and drive, but the battery, alternator, and starter are the usual suspects. These issues are especially common on classic cars with aging electrical components. So, when you pop the hood and check the battery, what do your battery posts look like? If they're corroded, read on for some steps to clean your car's battery terminals and tips to prevent them from corroding again.

Diagnosing & Cleaning Battery Corrosion


On the left, you can see a corroded battery terminal; on the right, there's a clean, good-condition terminal. If your car's battery looks like the first image, that corrosion is strangling the electrical current from your battery.

Corrosion is the electronic equivalent of bad cholesterol, and oxidation on the battery posts could easily be choking the flow of electricity from your battery. Thankfully, battery terminal corrosion is very simple to resolve with items you probably have lying around the house. The process of cleaning the corrosion doesn't take a long time and requires nothing more complicated than water, baking soda, and basic tools.

DIY Battery Terminal Cleaning

Safety First: When the cleaning solution reacts with corrosion, it's likely to cause fizzing and splattering. We strongly recommend using safety glasses to protect your eyes. If you are fond of your clothes, we also recommend wearing an apron. Also, make sure you're working in a well-ventilated area.


Mix baking soda and water into a thin paste, then carefully scrub the terminals, posts, and cables with the paste using a brush or a dedicated battery post and terminal tool. Finish by rinsing each with clean water and drying with a towel.


Above: A battery post and terminal tool features sharp steel blades that scrape away corrosion from terminal posts and clamps.

When Cleaning Isn't Enough

This colorful collection of oxides doesn't even resemble a battery terminal.

This colorful collection of oxides no longer resembles a battery terminal. Time to replace it. After cleaning the corrosion, you may discover your terminals to be in pretty bad shape. We have plenty of replacement battery terminals if yours are severely corroded.

Preventing Battery Corrosion & Damage


You may want use anti-corrosion felt washers before you reattach the battery cables. Using dielectric grease on the battery terminals will isolate the metal parts from the oxygen in the air to help prevent oxidation.

At this point, since you're already working with the battery, it's a good idea to protect your battery tray and engine bay against corrosive acid leaks with a battery mat, available in your choice of yellow or black. These mats absorb leaking battery acid before it can pool under the battery and create a haven for rust.

If your battery tray has already fallen victim to acid, then you'll need to replace it before things have a chance to get any worse. The last thing you want is for the corrosion to spread like an infection throughout your engine bay. We stock a huge selection of replacement battery trays for virtually every model year of each vehicle we service.

Long-Term Battery Health Tips


This is a great time to upgrade to a quick disconnect terminal to prevent your electrical accessories from draining your battery while parked. Add a low-current charger to protect against the battery's slow self-discharge, and plug in a memory saver to prevent your clock and any computer modules from resetting. These steps will ensure your engine is ready to start when you are.

Need Classic Car Batteries & Components?

Classic Industries specializes in offering parts for classic cars such as the Chevrolet Camaro, Pontiac Firebird/Trans Am, and Ford Mustang. If you own a classic car, click the button below to view our extensive selection of parts catalogs and request a free catalog for your home, garage, or workshop.