How to Clean Battery Connections

Your car battery’s main role is to allow your engine to start when you turn the key. It is a reserve power source as well, in case there is more demand for power than your alternator can produce while your engine is running. It needs to operate as intended every time you start your car.

Over time and use, corrosion can form on your car battery’s terminals in, on, and around the battery cable ends. The positive cable end connects your battery to the power distribution center that provides power to every system in your vehicle. The negative cable attaches to your car’s chassis to complete the ground circuit. If either one isn’t connected, you won’t have any power to start your car.

Corrosion forms on the terminal for two main reasons:

  • The terminal and the cable end are different types of metal
  • The battery is off-gassing hydrogen in the charging process

Corrosion shows up in the form of a crusty, fuzzy-looking substance that leaves a mess on your car battery terminals and cable ends. If enough corrosion forms between the cable ends and the terminals, it can actually prevent the battery’s power from flowing from the battery through the cables.

Corrosion on battery connections can be cleaned off using a couple of different methods, and you can help protect your battery from frequent corrosion.

Method 1 of 4: Remove the battery terminals

In order to properly clean your battery terminal connections, you’ll need to disconnect both the positive and negative cable ends from the battery.

Materials Needed

  • Battery terminal wrench)
  • Eye protection
  • Gloves

  • Warning: Always wear eye protection and gloves when working with a car battery to prevent accidental injury from battery acid.

person loosening connection ends

Step 1: Loosen the battery cable ends. Start by removing the negative cable first.

Place the battery cable wrench on the battery cable end nut and turn it counterclockwise.

Step 2: Loosen the nuts. If you have a top-post battery, you’ll just need to loosen the nuts until there is no tension on the clamp.

Step 3: Loosen the cable end. If you have a side-post battery, loosen the cable end until the cable is removed.

Step 4: Lift the top-post battery cable end off of the terminal. You may have to wiggle and pry the cable end off.

Method 2 of 4: Clean the battery with household items

You don’t need specialized equipment to properly clean the battery terminals on your car. A few simple household items can clean your battery and restore a proper connection.

Materials Needed

  • Baking soda
  • Petroleum jelly
  • Stiff-bristled brush or wire brush
  • Water

person applying baking soda to terminal

Step 1: Sprinkle baking soda over both battery terminals. Use enough for the powder to coat the terminal with a little around the terminal as well.

person pouring water onto battery

Step 2: Pour a couple tablespoons of water on each terminal. The baking soda will react by bubbling up quite ferociously for a couple seconds.

The reaction between the baking soda and water mixture and the acidic corrosion on the battery terminals will neutralize the acid, making it safe to handle.

Step 3: Repeat on the cable ends. Perform the same procedure for the battery cable ends.

You may prefer to perform this step in a small tub or just on top of the battery.

Step 4: Scrub the terminals. Immediately after neutralizing the corrosion, scrub the corrosion off with a stiff brush.

A wire brush is ideal but an old toothbrush will also do in a pinch.

Scrub all around the battery terminal as well as the cable end inside and out.

Step 5: Rinse with water. When all the corrosion is removed, rinse the battery and the cable ends thoroughly with clean water.

Step 6: Let the battery dry completely. You can blow it off with compressed air if you’d like.

person smearing petroleum jelly onto terminals

Step 7: Smear petroleum jelly on the battery terminals. A thin layer of petroleum jelly will conduct the electricity between the terminal and the cable end, while protecting the battery terminals from corrosion.

Method 3 of 4: Clean the battery with professional-grade supplies

There are products made specifically for the purpose intended here. Battery cleaning equipment and sprays perform an exemplary job quickly and easily.

Materials Needed

person spraying cable ends with cleaner

Step 1: Spray the cable ends. With the battery cables disconnected, spray the cable ends and the terminals with battery cleaner spray.

The spray neutralizes the acid and corrosion. Many sprays have a dye in them that shows up when acid is present. For example, a yellow spray might turn purple in the presence of acid.

Step 2: Soak for a few minutes. Let the battery and cable ends soak in the spray for a few minutes. You’ll notice the color dissipate.

Step 3: Spray again. Spray the battery terminal and cable ends once again lightly with the cleaner spray. If the color doesn’t change or only changes slightly, the acid is neutralized.

Step 4: Rinse with water. Rinse the battery completely with water.

Get all the cleaner spray off the battery and the surrounding areas.

  • Warning: Don’t get the battery cleaner spray on your paint job. Some dyes will permanently stain your paint another color.

person scrubbing with battery brush

Step 5: Use a battery brush. Clean the battery posts and cable ends with a battery brush.

For a top-post battery, place the battery brush over the terminal and turn it 3-4 times around the post.

The stiff wire bristles will whisk away any corrosion on the terminal. You can also use a stiff-bristled brush if you have a side-post battery.

person inserting battery brush into cable end

Uncap the battery brush and insert the brush into the cable end.

Turn it 3-4 times around as well, removing any corrosion build-up in the clamp.

Step 6: Spray the battery terminals. Spray them with battery protector spray or wipe a thin layer of petroleum jelly onto the terminals.

Method 4 of 4: Reconnect the battery terminals

All you’ll need is your battery terminal wrench to reconnect the cable ends.

Step 1: Replace the cable. Place the positive battery cable end back on.

For top-post batteries, you may have to tap or wiggle the cable end down fully into place.

Step 2: Tighten the nut. Tighten the nut on the clamp until it is snug, then add another quarter turn.

Step 3: Repeat for the negative cable. Install the negative battery cable in the same way.

As you clean your car battery terminals and cables you may notice damage on your battery or cables that requires the attention of a professional. Be sure to contact a certified mechanic, such as one from YourMechanic, who can come to your home or office and service your battery or replace your battery or cables if necessary.


Next Step

Schedule Car is not starting Inspection

The most popular service booked by readers of this article is Car is not starting Inspection. Once the problem has been diagnosed, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Car is not starting Inspection reviews

Excellent Rating

(13,096)

Rating Summary
12,076
521
89
99
311
12,076
521
89
99
311

Kenneth

20 years of experience
678 reviews
Kenneth
20 years of experience
Nissan Stanza - Car is not starting - Compton, California
When determining why my mother's car would not start, Mr. Kenneth V. has prompt professionalism with a plethora of car knowledge and expertise, for thorough problem-solving skills.
Dodge Durango - Car is not starting - Los Angeles, California
Kenneth was prompt, and very honest. Unlike most mechanics who exaggerate the problem, and try to get you to pay for things that aren't there, he came to the point. I will request him for future car problems I may have.

Stephen

32 years of experience
112 reviews
Stephen
32 years of experience
Toyota Avalon - Car is not starting - Arvada, Colorado
Very professional and knowledgeable, went above and beyond to try to find out what is going on with car.
Honda Accord - Car is not starting Inspection - Erie, Colorado
Stephen was wonderful to work with. He was on time and got right to work. He was straight forward and explained things very well.

Michael

21 years of experience
156 reviews
Michael
21 years of experience
Hyundai Santa Fe - Car is not starting - Riverside, California
Friendly, knowledgeable, and honest. I've had problems with my car for the last six months and have felt more and more uncertain about what to do and even more confused about what the problem was. After meeting with Mike, I feel more at ease and confident that I have a plan for my vehicle. Peace of mind I haven't had in a while. Thanks, Mike.

Christopher

21 years of experience
24 reviews
Christopher
21 years of experience
Toyota Camry - Car is not starting - Cartersville, Georgia
Christopher is awesome. Very friendly guy and im happy he is the one i booked for my next service. Thanks

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

10 Biggest Car-Related Headaches and What to Do About Them
You You don’t want to, but if you're a car owner it's inevitable that at some point you will experience car troubles. It's also fairly certain that the machine you rely on will cause you grief when you least expect...
Alternator or Car Battery: How to Tell Which Part Is the Problem
When When you need to go somewhere and your car won’t start, it’s not unreasonable to think that you could have a car charging problem. A jump start might fix it in the short term and get you to work...
How to Replace an Instrument Voltage Regulator
The instrument cluster has a voltage regulator that fails when the panel is dim or flickering, reads erratically, or is totally inoperable.

Related questions

What’s the range on the electronic key?

Your electronic key lets you lock and unlock the doors, the rear hatch and even start the car. However, it needs to be with you to do that. You also have to be within range of one of the antennas...

For three days, car won't start and jump-started - 2014 Ford C-Max

Hello. Although this may sound like a simple answer, it is very possible that you could have a loose ground connection near your battery. This is often times overlooked by even the best mechanics because it is such a simple...

Car won't start after being parked

When the key is turned and nothing happens could mean several things; you have a bad battery (most common), the switch is bad, or the starter is not working. If you hear a click when you turn the key and...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com