Yesterday, I disconnected my car battery for a quick cleanup, and what I found shocked me. The battery terminals were covered in a thick layer of white, crusty corrosion that I had completely ignored for months.
This was the reason why my car had been struggling to start for the last few days. If you’ve ever heard the dreaded slow crank while turning on the ignition, it is a clear sign of dirty or corroded car battery terminals.
If left unnoticed, several negative effects can occur. Corrosion can reduce battery performance, damage your car’s electrical components, and even cause electrical short circuits.
In extreme cases, the battery may leak acid, damaging other essential parts of the vehicle. So, immediately start cleaning the battery terminals to prevent these issues. You don’t need any fancy tools or mechanical experience, just a few household items and the right steps.
In this guide, I’ll walk you through how I cleaned my car battery terminals and some regular battery maintenance tips to prevent future corrosion.
What Causes Corrosion on the Car Battery Terminals?
Corrosion on the car battery terminals is a chemical reaction between the battery’s electrolyte and metal terminals, often triggered by leaking fluid or overcharging.
Here are some reasons behind the corroded battery terminals.
- Overcharging: If your car battery is being overcharged, it can heat up and cause the electrolyte to expand, finding its way to escape through the vents, ultimately leading to corrosion.
- Leakage: Over time, cracks can occur in the battery, causing the sulfuric acid to leak out. If the acid comes into contact with the terminals, it can lead to corrosion.
- Old Battery: If your car battery gets old, it is common that cracks and leakage can occur in the battery, causing corrosion.
- High Temperature and Humidity: If you’re living in an area with high temperature and high humidity, it can accelerate corrosion by interacting with the battery’s gases and moisture in the air.
Tools and Materials Needed to Clean Car Battery Terminals
Let’s walk through the list of tools and materials I’ve used to clean my car battery terminals.
- Safety gloves and goggles to protect against electrical short circuits or sparks.
- Wrench or pliers to loosen and tighten the terminal clamps.
- A toothbrush for scrubbing away corrosion.
- A mixture of baking soda and water to neutralize acid corrosion.
- Distilled water for rinsing the terminals after cleaning.
- Clean, dry rags for drying the terminals.
- A terminal protector spray to prevent future corrosion.
Step-by-Step Instructions For Cleaning Car Battery Terminals
Here are the steps I follow to clean my car’s battery terminals.
Step 1: Turn Off the Ignition and Lift the Hood
The first step is obvious. I just turn off the ignition and lift the hood. Turning off the ignition is essential to prevent electric shocks.
Step 2: Locate the Battery and Assess Its Condition
Under the hood, I located the battery and visually inspected its condition. You may usually find the battery under the hood. But in some cars, it may be present under the passenger seat or in the trunk.
While inspecting, if you find any leakage or cracks in the battery, you have to call a professional or replace the battery. Thankfully, in my case, it was just corrosion.
Step 3: Remove the Covers From the Battery Terminals
Next, I removed the red and black covers from the top of the battery terminals.
- Black cover on the negative terminal
- Red cover on the positive terminal
I removed the covers to closely examine the battery cables and clamps for excess wear or corrosion. You can identify corrosion as a white, ashy deposit. If cables and clamps are severely corroded, it is time to replace them altogether to avoid future problems.
In my case, it was just a minor corrosion that could be cleaned at home.
Step 4: Disconnect the Negative and Positive Terminals
To thoroughly clean the battery, I disconnected both the negative and positive terminals. I loosen the nuts on the negative terminal first, then the positive terminal, using a wrench. After removing the terminals, I carefully removed the battery.
You can check out my guide on how to disconnect a car battery safely. It’s the perfect companion to this tutorial and will help you avoid common mistakes you may make while disconnecting the battery.
Sometimes you may have difficulty removing the clamps, especially if they are heavily corroded. In this case, you need pliers to remove the clamps. While using pliers, be careful not to touch the tool to the car frame or the battery, as this could cause a short circuit.
Step 5: Make a Mixture of Baking Soda and Water
I made a thick paste of baking soda and water to clean the battery corrosion. I combined 2–3 tablespoons of baking soda with 1 tablespoon of distilled water in a small bowl and stirred until all the baking soda dissolved.
You can also use a commercial battery cleaner instead of making your own mixture.
Step 6: Apply the Baking Soda Paste on the Corroded Parts
I applied the baking soda mixture over the corroded areas using a soft cloth or toothbrush. Once the mixture is applied, you’ll notice bubbles and foam as it reacts with the corrosion.
You have to leave the mixture for at least 5-10 minutes to soak in and loosen the corrosion. Be very careful when using the baking soda mixture, as it can damage other components of your car.
Step 7: Gently Scrub the Corroded Areas
Next, I gently scrubbed the corroded terminals with a toothbrush. If the old paste wears away, you can add more paste and keep scrubbing until the corrosion is gone. If you need something stronger and stiffer than a toothbrush, you can use special terminal brushes.
Step 8: Wipe Away the Baking Soda Paste
I dipped a clean cloth in distilled water and wiped away the paste. Make sure to keep dipping the cloth into the water as it dries, and continue wiping until the mixture is completely removed.
Step 9: Dry Off the Terminals With a Clean Rag
Once the mixture was wiped off, I dried the battery terminals with a clean, dry rag. Make sure the terminals are completely dry before reconnecting the battery. Remember, you don’t have to use a paper towel, as it will leave bits of paper towel stuck to the battery terminals.
Step 10: Apply a Terminal Protector Spray to Prevent Future Corrosion
In the last steps of cleaning, I applied a terminal protector spray across both the positive and negative battery terminals to prevent future corrosion. You can also use petroleum jelly instead of the spray.
Just take some jelly on your fingers and smear a thin layer across both cleaned terminals.
Step 11: Reconnect the Terminals
Once the cleaning was done, I reconnected the battery terminals. First, I connected the positive terminal and then the negative terminal.
Common Mistakes to Avoid While Cleaning Car Battery Terminals
Here are some common mistakes to avoid while cleaning car battery terminals.
- Not Wearing Safety Gear: Make sure to wear proper safety gear (gloves and glasses) to prevent your skin from coming into contact with corrosive acid inside the battery.
- Using the Wrong Tools: If you’re using steel tools, you’re bridging both terminals at once, causing a short circuit.
- Using Inappropriate Cleaning Solutions: Avoid sticky solutions or harsh chemicals, such as bleach or strong acids, which can attract dirt and leave residues that interfere with your car’s electrical components.
- Cleaning While the Engine is Running: One of the most common mistakes is cleaning the terminals while the engine is running. It could be hazardous and can cause short circuits.
- Cleaning a Damaged Battery: Don’t ever try to clean a cracked, bulging, or leaking battery. It needs to be replaced immediately.
- Pouring Liquid into the Battery: Make sure to avoid any cleaning liquid getting into the battery vents, as it could neutralize the battery acid.
- Improper Connections: After completing the cleaning process, make sure all connections are correct. You have to reconnect the positive terminal first and then the negative terminal.
Why It’s Important to Clean Car Battery Terminals
Battery corrosion mainly occurs when acid fumes, moisture, and metal react over time, forming a crust that blocks electrical current. When corrosion builds up, the battery may struggle to deliver power to your car’s electrical components.
You may notice reduced battery performance, slow engine cranks, dim headlights, and other major electrical problems. In extreme cases, the battery may leak acid, damaging other parts of your car.
Therefore, it is essential to keep the battery terminals clean to ensure that electricity flows freely between the battery and your vehicle’s electrical system. Following simple cleaning steps can improve battery performance and extend its lifespan.
Additionally, it can reduce the risk of unexpected breakdowns, saving you time and money on costly repairs.
Symptoms of Dirty or Corroded Battery Terminals
Check out some symptoms of dirty or corroded battery terminals.
- Slow cranking or difficulty starting the vehicle.
- You may notice a white, blue, or green powdery residue around the battery terminals.
- Dim or flickering lights.
- Intermittent power loss or malfunctioning car’s electrical components.
- The battery warning light is blinking on the dashboard.
- The battery drains quickly, even when the vehicle is parked.
- A foul smell is coming from the battery.
- If there is excessive corrosion, it can cause cracks or damage to the battery.
Bonus Section: Regular Car Battery Maintenance Tips
It is crucial to keep your car battery in optimal condition to prevent sudden breakdowns, extend its lifespan, and keep electrical components working continuously. You can follow these tips to maintain a healthy car battery.
1. Regularly Inspect the Battery Terminals
One of the most common tips is to inspect the battery terminals regularly. A dashboard battery warning light can indicate the battery’s health. Another way to check the battery’s health is to use a multimeter.
If the reading is less than 11.5, it means the battery needs to be recharged. It is advised to call a professional to check the battery for damage as soon as possible.
2. Avoid Frequent Short Drives
If you’re frequently doing short drives, you have to stop it immediately, as the alternator lacks enough time to recharge the energy used to start the engine fully. As a result, the battery voltage will steadily decrease until it can no longer start the car.
Therefore, make sure to maintain your car’s battery by driving it frequently for at least 10 minutes.
3. Reduce the Power Consumption When the Engine is Off
You have to reduce the power consumption when the engine is not running to prevent battery drainage. Always ensure that all electrical accessories, like lights, AC, or the heater, are turned off when the engine is off.
4. Keep the Battery Clean
Make sure to keep the battery clean, free of dirt and corrosion. A dirty or corroded battery can lead to reduced battery performance and a short lifespan. If dirt or corrosion is left unchecked, it can even cause leakage or damage to the battery, leading to short circuits and sparks.
5. Don’t Use Acid to Clean the Battery
As discussed before, never use harsh acid to clean your car battery terminals, as it can cause corrosion or severe damage to the battery. You should only use distilled water or a specialized cleaning solution to keep the battery functioning for a long time.
It is also advisable to call a professional to clean the battery, as they know which cleaning solutions are appropriate.
6. Don’t Keep the Car Exposed to Heat for a Long Time
If you keep your car exposed to heat for a long time, it could cause the fluid in the car battery to evaporate. As a result, the battery performance will be ruined. In this case, make sure to park your car under the shade or inside the garage.
Wrapping Up
Keeping your car battery terminals clean will ensure a stronger electrical connection, smoother engine starts, and fewer sudden breakdowns. Cleaning terminals is also part of your regular maintenance routine to keep the battery in optimal condition.
The cleaning process takes just a few tools and minutes, helping you avoid costly repairs in the future.
Sources: wikiHow, AIS Windshield Experts, Bosch
Frequently Asked Questions
1. How Often Should I Clean My Car Battery Terminals?
It’s best to clean your car battery terminals every 3 to 6 months. If you live in a humid or coastal area where corrosion happens faster, check them more frequently.
2. What Causes Corrosion on Car Battery Terminals?
Car battery corrosion may occur if the battery is overcharged, leaking, or gets old.
3. Can I Clean Car Battery Terminals Without Disconnecting the Battery?
Cleaning while the battery is still connected can cause short circuits or sparks if the cleaning tool accidentally touches both terminals.
4. What’s the Safest Way to Clean Corroded Battery Terminals?
The safest DIY method is to use a baking soda and water paste. Apply it to the corroded area, scrub gently with a toothbrush, and rinse with clean water. Dry completely before reconnecting the terminals.
5. Can I Use Coca-Cola or Vinegar to Clean Battery Terminals?
While Coca-Cola and vinegar can help dissolve corrosion, they’re not ideal long-term solutions because they can leave sticky residue or react with metal.
6. How Can I Prevent Battery Terminal Corrosion in the Future?
After cleaning, apply a thin coat of petroleum jelly or a battery terminal protectant spray. This creates a thin layer that keeps moisture and acid fumes away from the metal.
7. What If My Car Still Doesn’t Start After Cleaning the Terminals?
If your car still struggles to start, the battery might be too weak or damaged. In that case, you have to immediately call a professional.
