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A Guide To Car Battery Corrosion (Removal, Causes, Prevention)

May 21, 2021

Car battery corrosion is a normal sign of battery wear and tear. 

But is it still something you have to worry about?

And if it is, how do you clean it off?

In this article, we’ll tell you why you should clean your vehicle battery terminals and how to do it. We’ll also cover why car battery corrosion occurs, how to prevent it, and highlight a simple solution to all your battery hiccups

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Let’s get into it.

What Does Car Battery Corrosion Look Like?

Most people tend to associate the idea of corrosion with brown, metallic rust. 

Battery terminal corrosion is a little different. 

Corrosion buildup on a battery terminal appears as a white, blue, or greenish substance with a powdery, granular texture.

The color of the corrosion depends on what kinds of chemical reactions have occurred

While small amounts of corrosion buildup are harmless, it can cause increasingly severe issues if left untreated

Let’s see why:

What Problems Does Car Battery Corrosion Cause?

Corroded battery terminals are one of the main culprits behind decreased battery life and performance. The corrosion interferes with the electrical current flow between the battery and the engine, and affects you in two ways. 

Not only does the car receive insufficient power, but the battery also won’t receive consistent recharging from the alternator either.  

What does this mean for your car?

A corroded battery terminal can prevent normal vehicle startups, which can result in you reaching out for those jumper cables every time you need to start your car.

Not ideal, right?

On top of that, unstable battery performance can lead to damage in other electrical components — like the air conditioning or even trigger issues on the vehicle’s onboard computer. And a  problem in the onboard computer can cascade to a variety of vehicle-wide complications. 

If you notice a corroded battery terminal or battery cable connector, the wisest thing to do is get it cleaned ASAP. 

How do you do that?

How To Remove Car Battery Corrosion

You can clean car battery terminal corrosion yourself with a few common household items. 

However, we still recommend bringing your car to a mechanic or calling one over. Having a certified mechanic perform the job is always a safer option. 

However, if you don’t have access to a mechanic, here’s what you need to do:

1. Gather Equipment And Check Battery

First, grab hold of the necessary equipment. 

You’ll need:

Before you start on the battery, check it for any bloating, swelling, or electrolyte leakage

If you notice any of these, get a mechanic to look at it instead.

2. Detach Battery Cables

Before you detach the battery cables, make sure the car ignition is off

Next, the sequence you disconnect each battery cable is essential to avoid any electrical shocks.

Detach the negative cable (black) from the negative terminal FIRST. 

It’s the one with the “-” sign or abbreviation “NEG.” 

Then, detach the positive cable (red) from the positive terminal. 

This one has the “+” sign or the abbreviation “POS.”

What if the battery connection is too corroded and tight?

If a battery terminal is too corroded and the terminal clamp is locked on tight, don’t force it, or the battery post might break. 

Instead, apply your terminal cleaner and leave it on for a few minutes to help loosen the connection.

3. Inspect Battery Cables

Check each battery cable for any damage as it’s a common reason your car won’t start. If any cable insulation is cracked, frayed, or corroded, your mechanic should replace it.

4. Loosen Car Battery Corrosion

There are three types of solutions you can use to clean car battery corrosion. 

However, before you start, do not let any cleaning solution or corrosion elements fall on other engine parts. It’s best if you can take the battery out of the engine bay before you proceed.

Now, let’s go over those solutions:

A. Baking Soda Solution 

The baking soda and water solution is a simple method to clean corrosion and is known to be effective. 

You can apply this in one of two ways:

The baking soda solution triggers a chemical reaction that loosens the corrosion. 

For very heavy corrosion: soak a paper towel or tissue paper in the baking soda solution and place it on the battery terminal. You can also soak a corroded battery clamp in a cup with the baking soda solution. Leave for about 20 minutes before scrubbing.

B. Battery Terminal Cleaner

There are many commercial-grade battery cleaners on the market and typically come in the form of a cleaner spray. A battery terminal cleaner will help clear the corrosion and neutralize battery acid and is probably worth investing in if your battery is heavily corroded.

Just make sure it doesn’t touch your paint job, as some terminal cleaning agents can cause a permanent stain.

C. Fizzy Drinks

This may seem odd, but any soft drink with carbonic acid (fizzy drink) can loosen battery corrosion too. 

However, exercise caution here, as these drinks tend to contain synthetic sugars and phosphoric acid that can be damaging to your engine components.

Only use this as a last-ditch attempt when you don’t have access to any other cleaning solutions or mechanics.

5. Scrub Clean Battery Corrosion

Next, scrub the battery terminal with a wire brush or battery brush to remove the corrosion. You can even use an old toothbrush if you don’t have anything else available. 

Do the same for the terminal clamp. 

6. Rinse And Dry

Once all the corrosion has been removed, rinse each battery terminal and battery clamp with clean water. Let it air dry or wipe it down with a rag. You can use an air compressor to speed up the drying.

Apply a protective grease like petroleum jelly onto the battery terminals to lubricate them and prevent future corrosion. 

7. Reconnect Battery

When reconnecting the battery terminals, follow the reverse order of steps you took when detaching the battery

Attach the positive battery terminal (red) FIRST, then the negative terminal (black). Secure everything tightly with a wrench as loose connections can impede charge transfer between the battery and engine. 

Now that your battery is clean, let’s examine why car battery corrosion occurs.

Why Do Car Batteries Corrode?

Battery terminal corrosion crops up for many reasons. 

We’ll look at six of the most common causes.

1. Vented Hydrogen Gas

The conventional lead-acid battery is filled with an electrolyte solution of sulfuric acid and water. 

A chemical reaction in the battery generates an electric current, which in turn produces hydrogen gas that’s released through top venting blocks. The gas can also leak through the fissure where the battery post meets the plastic casing. 

This vented hydrogen gas reacts with other gases and substances in the engine compartment, resulting in corrosion. 

Sometimes, the location of corrosion can indicate battery issues. 

An undercharging battery may often have corrosion on the negative terminal. However, if the corrosion occurs on the positive terminal, the battery is typically overcharging instead.

2. The Battery Leaks Electrolyte Solution

A tipped or damaged lead acid battery can leak electrolyte solution. 

When this happens, the electrolyte solution may accumulate on the battery terminal, causing corrosion.

3. An Overfilled Car Battery

Some lead-acid batteries require topping with battery water every few months. 

If the battery is overfilled, the electrolyte can leak through the battery vents, overflow onto the metal terminals and corrode them. 

Batteries should be topped up to the highest marker and no further. 

4. Overcharged Car Battery

Overcharging a battery raises its temperature. 

The electrolyte volume will expand and can even boil and steam acidic gases through the vents. The leaking sulfuric acid steam or liquid can cause corrosion on battery terminals. 

5. Chemical Reaction On Copper Clamps

The copper in the terminal clamp is a good conductor of electricity and doesn’t corrode easily. 

However, the combination of leaking sulfuric gases from the battery and an electrical current can create copper sulfate, which causes corrosion. 

This blue-green substance you see on a terminal isn’t a good conductor and should be cleaned. 

6. Old Battery

Terminals unavoidably corrode as the battery ages and lose its ability to hold a charge. If your car battery is close to 5 years old, it’s time to swap in a new one before you have a dead battery on your hands. 

While battery corrosion is unavoidable in the long run, there are ways to slow its progression and extend your battery life. 

5 Ways To Prevent Car Battery Corrosion

Here are methods you can use to prevent future corrosion of your car battery.

1. Felt Battery Washers

Battery terminal protectors like felt battery washers are one of the easiest solutions to protect your battery against corrosion. These washers are chemically treated to help absorb the vapor released at the battery post and last for several years to help keep the terminal clean. 

However, remember to apply some protective grease to the top of the washer and car battery terminal before installing. 

2. Protective Coating

You can use a protective battery grease or petroleum jelly on the battery terminal to prevent corrosion. Battery grease lasts longer than petroleum jelly when exposed to engine heat as it’s silicone-based. 

Alternatively, a rust inhibitor spray could also work just as well. 

3. Resolve Battery Charging Issues

If you suspect that your car battery is corroding because of undercharging or overcharging, bring your car to a mechanic to rectify the electrical fault. 

Charging issues could concern more than just the battery itself.

4. Copper Compression Terminals

Consider using copper compression terminals at your battery terminal ends. These are made from tinned copper and allow a full 360o contact with the battery cable, which helps distribute the electric current evenly and prevents corrosion.

5. Have A Regular Maintenance Schedule

Keeping up regular vehicle maintenance ensures that your car battery is routinely inspected and maintained.

While these five tips can help you prevent corrosion, it can still creep in over time and cause bigger issues.

When that happens, what do you do? 

An Easy Solution To Battery Corrosion And Other Car Issues

Knowing how clean your car battery is essential, as it’ll help you prolong your battery life. 

However, if you have other battery concerns, like leakage or charging instability, or if you don’t want to perform the corrosion cleaning yourself, you can always let a mechanic help you.

And you’re in luck, as RepairSmith can help you with all those needs. 

RepairSmith is a convenient mobile vehicle maintenance and repair solution. Here’s why you’ll want them to handle your battery concerns:

For an accurate estimate of battery repair and replacement costs, fill this online form.

Closing Thoughts

While battery corrosion is a common phenomenon, too much of it can signify a more serious underlying problem. 

If you’re concerned, simply contact RepairSmith

Their ASE-certified professionals will be at your doorstep, ready to lend a hand and fix any battery-related issues!