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How can I keep my car battery from corroding?

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Updated 6 Sep 2021

Zak Zuiderduin

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Battery terminals are the point of contact between the battery and your car’s electrical system.

If there is a problem here, your car’s performance can be affected and, potentially, damage can be caused to the electrical system as a whole.

It’s important, therefore, to try and keep the terminals free of corrosion – a very common cause of battery issues.

What is battery terminal corrosion and what does it look like?

If you look under the bonnet of your car at the battery and notice there is a visible formation of white powder or dirty stains around the terminals, you are probably looking at terminal corrosion.

What causes corrosion?

When the battery is charging or discharging, there is a chemical reaction happening which affects the different metals close by.

A battery that is overcharging is more prone to corrosion and it is usually more noticeable on the positive terminal.

It can also be caused by your battery nearing the end of its life.

How do I clean it?

The best and easiest way to clean the corrosion is by using bicarbonate of soda (baking soda) and hot water.

Apply some water and baking soda and, using an old toothbrush or something similar, clean the corrosion away.

Rinse off with plenty of hot water.

Make sure you use eye protection and gloves - if you get battery acid/corrosion onto your clothes, it will eat holes into it.

It can also damage the paint on your vehicle.

For a thorough clean, the battery terminals need to be removed.

However, by removing the battery terminals you will lose your car’s clock settings, radio presets and other items kept in your vehicle’s memory.

A professional workshop will use a memory retention device so you don’t lose these settings.

How do I control corrosion?

Now that the battery terminals are clean, you can slow down the corrosion process by coating the terminals with petroleum jelly (Vaseline), grease, or aerosol battery terminal protectors that you can get from your auto parts store and which are designed to protect battery terminals from corrosion.

Whichever method you use, make sure that the metal on the terminals is fully covered so they are not exposed to the air and other gases.

Battery terminal corrosion can damage your vehicle's electrical system.

A dirty connection is a bad connection and must be fixed, and if you are uncertain of what to do, you should always consult a professional who is trained to identify, repair and service these types of issues.

If you need a new battery, use AutoGuru to search and book a battery specialist.

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Written By

Zak Zuiderduin

Zak has been working in the auto industry for 40 years.

For the past decade, he has been in the education business, training apprentices and preparing them for a career in the light vehicle and auto electrical trades.