Blog Car Care Advice How to Remove Car Battery Corrosion (+Why You Should Do It)
Car Care Advice

How to Remove Car Battery Corrosion (+Why You Should Do It)

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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?

This article will explain why you should clean car battery terminals and how to do it. We’ll also cover why car battery corrosion occurs and how to prevent it.

This Article Contains

Let’s get into it. 

What Does Car Battery Corrosion Look Like?

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

Battery terminal corrosion is a bit different. 
Corrosion buildup on a battery terminal appears as a white, blue, or greenish substance with a powdery, granular texture. The corrosion color 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. 

The car receives insufficient power, and the battery won’t receive consistent recharging from the alternator.  

What does this mean for your car?
A corroded battery terminal can prevent normal vehicle startups, making you reach for those jumper cables whenever 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 various vehicle-wide complications. 

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

Note: It’s important to know the difference between corrosion and sulfation. You can easily remove corrosion when doing scheduled maintenance. However, sulfation usually means severe damage to the battery.

How do you clean car battery terminals?

How to Remove Car Battery Corrosion

You can clean car battery terminal corrosion yourself with everyday household items like vinegar and lemon juice. Combining lemon juice and vinegar is an excellent way to combat rust and corrosion. Baking soda is another common item used for removing battery corrosion. 

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

If you don’t have access to a mechanic, here’s what you need to do to clean car battery corrosion:

1. Gather Equipment and Check the Battery

You’ll need the following equipment to clean battery corrosion:

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 them instead.

2. Detach Battery Cables

Before detaching the battery cables, ensure the car ignition is off. 

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

Detach the negative battery cable (black) from the negative battery terminal FIRST. 
It’s the one with the “-” sign or abbreviation “NEG.” 

Then, detach the positive cable (red) from the positive terminal. 
The positive battery terminal has the “+” sign or the abbreviation “POS.”

What if the battery connection is too corroded and tight?
If a battery terminal is too rusty and you have a locked terminal clamp, 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 cable insulation is cracked, frayed, or corroded, your mechanic should replace it.

4. Loosen Car Battery Corrosion

You can use three solutions 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 to take the corroded battery out of the engine bay before proceeding.

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 two ways:

  • Take one tablespoon of baking soda and mix it with a cup of water, then pour it onto the corroded battery terminals. 
  • Alternatively, coat the corroded areas with baking soda first, then slowly pour on the water. 

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

Many commercial-grade battery cleaners are on the market and typically come as a cleaner spray.  A battery terminal cleaner will help clear the corrosion and neutralize battery acid and is probably worth investing in if you have a heavily corroded battery.

Just ensure 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 or soda) can loosen battery corrosion too. 

However, exercise caution here, as these drinks tend to contain synthetic sugars and phosphoric acid that can damage your engine components. Only use this as a last-ditch attempt when you cannot access any other battery cleaning agent 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 have nothing else available. 

Do the same for the terminal clamp. 

6. Rinse and Dry

Once you’ve removed the corrosion, 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 clean battery terminals to lubricate them and prevent battery 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 the 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 contains an electrolyte solution of sulfuric acid and water. 

A chemical reaction in the battery generates an electric current, producing 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 overcharged instead.

2. The Battery Leaks Electrolyte Solution

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

When this happens, the electrolyte solution of a lead acid battery 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. An overfilled battery can leak electrolytes 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 boil and steam acidic gasses 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 gasses from the battery and an electrical current can create copper sulfate, which causes corrosion. You should clean the blue-green copper sulfate on a terminal since it isn’t a good conductor. 

6. Old Battery

Terminals unavoidably corrode as the battery performance declines, and it loses the 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 battery corrosion:

1. Anti Corrosion Pads

Battery terminal protectors like felt battery washers are one of the easiest solutions to protect your battery against corrosion. These chemically treated anti corrosion pads 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 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 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 360° contact with the battery cable, which helps distribute the electric current evenly and prevents corrosion.

5. Have a Regular Maintenance Schedule

Keeping up scheduled 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 more significant issues. When that happens, your best solution is to get a battery replacement. 

Closing Thoughts

While battery corrosion is common, too much can signify a more serious underlying problem. If you have other battery concerns, like leakage or charging instability, or don’t want to perform the corrosion cleaning yourself, contact AutoNation Mobile Service.

With AutoNation Mobile Service, you can easily make a booking using our online platform. Our expert technicians will drop by your driveway to lend a hand, and we offer a 12-month | 12,000-mile warranty for all repairs. 

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