battery terminal corrosion

Battery Terminal Corrosion – Causes & How to Prevent it

In Electric by Magnus Sellén8 Comments

battery terminal corrosionYou have probably encountered a whiteish substance on your battery terminal when you are opening your hood.

The car’s battery is vital for the smooth operation of the automobile. It controls tasks like ignition, headlights, listening to the radio, or operating the AC.

Having a car stall in the middle of the road can be embarrassing for many, and if you do not have jumper cables, you may find yourself stranded in the middle of nowhere.

Battery terminal corrosion will appear after years of driving with the same battery, and you need to understand what causes it and how to fix it.

Causes of Battery Terminal Corrosion

There are a few different reasons why you may notice corrosion on your battery terminals. Here are the most common reasons:

1. Hydrogen gas leakage

The battery turns acid into electric current. There are moments that the hydrogen gas in the battery leaks and finds its way into the atmosphere. It reacts with other substances, and you get battery terminal corrosion.

Depending on which side it forms, you can diagnose various battery problems – if it is on the negative terminal, this is a sign of undercharging while if it is on the positive terminal, it is due to overcharging. Most batteries suffer from undercharging, and this is the reason you see it more on the negative side.

2. Electrolyte leakage

This problem is synonymous with lead-acid batteries. Due to age or damage, the electrolyte in the battery can leak and accumulate on the battery terminals. The probability of the electrolyte leaking is increased if you overfill the battery water.

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3. Corrosion in the copper clamps

battery terminalsCopper is a good conductor and does not corrode easily. However, when electric currents pass through the copper terminals, there is the production of copper sulfate, which leads to battery terminal corrosion.

A bluish precipitate on the copper terminals can signify copper sulfate. Copper sulfate does not conduct electricity well, and that is why you will start experiencing trouble starting your car.

4. Overcharging and overfilling the battery

If you overfill your battery with water, it can cause the electrolyte to leak through the vents and corrode the terminals. Ensure that you put in the right amount of battery water.

If you overcharge your battery, something similar happens – the electrolyte gets charged upon kinetic energy and overflow to the terminals, causing corrosion.

How to Fix it

Baking soda – water solution

If you want to remove copper sulfate that has accumulated on the terminals, you will need some baking soda water solution and a brush. First, ensure that the car’s ignition has been turned off. Remove the battery terminals and use your brush to remove some of the corrosion.

Pour the baking soda solution and continue removing the corrosion with your brush. Once done, clean the terminals with some clean water. It is prudent to smear some wheel bearing grease on the terminals to prevent further damage. Some people may opt for petroleum jelly, but this does not last as long as grease.


Most of the soft drinks that we take have some carbonic acid in them. Pour some of the soda on the terminals and use a soft sponge to remove the residue. This works well in the absence of a baking soda-water solution.

Cleaning heavy corrosion

If your battery has excessive corrosion on the terminals, you will need to use baking soda-water solution and an old toothbrush. Start by removing the battery terminals – the negative should be first. Mix your baking soda solution and place it in cups. Soak each of the terminals in the solution and let it soak for the next 20 minutes.

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Scrub off the corrosive materials on the terminals. Pour in the soda solution and make a fresh one. Soak the battery terminals again while removing the corrosive materials. Clean the terminals with water and let them dry or wipe with a damp cloth. You can also use sandpaper to clean the terminals. Apply some grease or Vaseline and reattach the terminals – start with positive.

Reviving an old battery using aspirin

There is that moment when your battery has outlived its purpose, but you need just one more charge to keep you going. If you have some aspirin tablets, you can pop two into the battery, and you will get one more charge. Aspirin has acetylsalicylic acid which, when combined with the battery’s sulfuric acid, gives you a charge.

Preventive Measures

Copper compression terminals

These clamps are one of the best in the market and will help prevent further battery terminal corrosion. The clamps are made from tinned copper and ensure that the whole clamp comes into contact with the electric current.

Battery charging

One of the causes of battery terminal corrosion is a battery that is overcharged or undercharged. The manufacturer’s manual often has the recommended battery voltage. You should adhere to this if you want to prevent corrosion forming on the terminals.

Anti-corrosive sprays

There are various sprays that are available on the market to prevent terminal corrosion. You can also use Vaseline or grease if you find the sprays expensive. Coated felt pads could also be used to prevent corrosion of the battery terminals.


The battery is a vital component of a car. It sends electricity to the starter which in turn sends electrical signals to the spark plugs and your car starts. When your battery is low on power, you will experience problems starting it.

Causes of low battery vary – it could be that your battery is old or the terminals have excessive corrosion. The lead-acid battery uses a sulfuric acid mixture to generate power. Hydrogen molecules leak into the atmosphere and when mixed with other compounds form corrosion on the terminals.

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If you are far from home, you can use soda to remove the corrosion. Soda has carbonic acid which reacts with the corrosive substance. If you are home use a baking soda – water solution. Pour in the contents on the corroded battery terminals while removing the substance with a soft brush. Wash off the area with clean water.

You can also smear some grease or Vaseline on the terminals to prevent further corrosion. It is wise to always check the voltage of your battery – undercharging and overcharging can cause battery terminal corrosion.

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.

8 thoughts on “ Battery Terminal Corrosion – Causes & How to Prevent it ”

  1. You can’t stop accumulation of acid on the terminal I have tried all above and decided that some batteries do and most don’t leak acid, the easiest way to clean it is to pour boiling water over it while brushing it, it dissolves the acid no problem, then clean contact surfaces with steel wool , covering with grease or equivalent may prolong the buildup, hose down around the battery toget rid of any acid that might cause rust to bodywork in the vicinity

  2. About how long does it take for corrosion to eat away at the battery cable/terminal to where it break the terminal and cable apart? I have a 2017 and I bought it used at the end of June 2019 and at the end od September 2019 the mechanic was taking terminal off the battery to check thw battery for one and to clean up the corrosion around it and when he undone it the cable/terminal broke apart to to the corrosion. Of corse no warranty to help me out because its a “maintenance” issue. Im sorry and maybe Im wrong but wouldn’t or shouldn’t the battery and battery cables be good for more than 2 years? And if acid eats the cable wouldn’t it take longer that 3 months to comply eat away the cable? I guess my question is, how long does it take and how can i grt help paying for something that I dsidnt couse, I’ve only had it 3 months.

    1. Pouring a little petrol on the terminals instantly removes the corrossion on terminals no stress of steel wool or scrubbing with old toothbrush

      1. They are incredible, but they are not straight forward. They haven’t answered my question but yet the best.

    2. Battery cables and terminals aren’t super expensive. I’ve found that if you are a women, a lot of the time if you go to an autozone or oreilly auto parts store of you ask nicely one of thre workers will help you out. If not usually anybody with just a socket set and maybe a screwdriver cam change them out in about a half hour.

  3. OK. It exposes my age but in a state automotive school contest I was the only one in the state to answer the question correctly. You say “Start by removing the battery terminals – the negative should be first.” That is an incorrect statement as not all vehicles have negative ground electrical systems. Many vintage vehicles and equipment have positive ground systems. A correct statement is to remove the GROUND cable first. An excellent way to clean badly corroded cables is to soak the terminal overnight in Coca-Cola. They will come out like a new penny. I would also shy away from the “emergency” bolt on terminals. Electricity travels around the wire strand not through it. A bolt on cable does not have sufficient contact to carry the load. If your terminal is so poor it requires replacement use a new factory cable.

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