Battery Terminal corrosion -causes, how to remove, prevention
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If you have an old car or one day decided to leave your car in the garage for an extended period then you have encountered battery terminal corrosion. For many, battery terminal corrosion appears as some white paste on top of the terminals. Ignoring this only deteriorates your battery and you may wake up one morning to find your car won’t start.

If you want to prevent battery terminal corrosion you should disconnect the terminals when traveling or power up the car occasionally and leave it running for a few minutes.

Evidence of battery terminal corrosion does not mean that your battery is dead but with solutions offered in this article you should be able to breathe some fresh life to an old battery.

Symptoms of battery terminal corrosion

White/blue paste on terminals

blue paste on terminals

You know your battery terminals are corroded when you notice some white or blue paste on the terminals. This is as a result of interaction between the acidic elements of your battery.

Once these terminals become corroded they prevent the smooth transmission of power to the car. You should not try to touch this corrosive substance with your bare hands.

Difficulty starting the car

The moment your battery becomes corroded you are going to experience problems starting the car. This is because the corrosion interferes with the smooth operation of the electric current to the car system. The loss of electrical power will extend to other car parts that need electricity like the wipers, headlights or car alarm.

Causes of Battery terminal corrosion

Electrolyte Leakage

In the case of lead acid batteries there moments the acidic fluids in the battery find their way to the battery terminals and interact with other compounds to form a corrosive element.

The electrolyte leak most of the times accumulates on the terminals. This corrosion is not relegated to lead acid batteries only but extends to hybrid cars that use lithium ion batteries.

Overcharging the battery

It is prudent that you charge the battery to the recommended voltage. When you overcharge it, the battery gets an excess of kinetic energy hence heating up and expanding. The excess electrolytes in the battery soon find their way to the battery terminals through cracks hence the corrosion.

This is also the case when you overfill your battery during charging. The excess water soon finds its way to the battery terminals hence leading to corrosion. You should fill up your battery to the recommended marks.

Copper terminals

While copper itself is not easily corroded it can react with the acidic compounds in the battery hence forming copper sulfate. This is what you see as a bluish substance on top of the battery terminals. The substance will weaken the electrical flow in your car and soon cause premature death of your battery.

Age of the car

A typical lead acid battery has an average lifespan of 5 years. After this you are going to notice frequent signs of terminal corrosion.

One of the first signs that your battery is old and needs replacement is when you start experiencing occasional starter problems or blinking lights. At this point no matter what you do, your battery will still not be restored to its powerful state.

How to remove battery corrosion

The first step is to clamping from the battery terminals. You will also need to disconnect the grounded wire which may be attached to the car’s body. This prevents accidental shocks when working on your battery.

Depending on the age of the battery, most of the corrosion is centered on the terminals. It can be a bit difficult removing the clamps so you may need to work with vice grips. Do not put too much pressure on the clamps as you may end up ruining them.

Next you need to examine the entire terminal cabling for signs of breakage. If the cables are broken then it is pointless cleaning them. Replacing them is the best course of action.

You may also want to check the entry point of the cables for any signs of corrosion. This would also be the right time to have a careful examination of the battery. If its bulging or leaking them removing the corrosion on the clamps would make little sense.

To boost your rate of conductivity the terminals have to be clear off any debris. To remove the corrosion begin with a coarse brush. Gently scrub off the inside and outside the terminals. This removes most of the corrosion.

Soda ash solution

battery terminal corrosion

Once you have brushed of most of the corrosive stuff, make a solution of baking soda and distilled water. Pour the solution on the terminals and leave it for a few minutes. Use a soft brush to rid of the terminals of the corrosion as you pour the baking soda solution.

Repeat the process until the terminals are free of any corrosive elements. Wash off with water and wipe with a clean cloth or wait for it to dry. When baking soda reacts with the acidic compounds you will hear a fizzling sound.

You should take extra care that the solution does not get into your hands or clothes as it is still highly corrosive. Before reconnecting the battery terminals you may need to apply some petroleum jelly on the terminals as this will prevent further corrosion. Once your clamps and terminals are super clean it is time to reconnect the battery.

If you do not have baking soda, most of the people will use carbonated drinks like “coke”. The procedure for removal is the same as with baking soda.

Replace terminals

Most of the time you experience battery terminal corrosion it is often with the cheap lead terminals. If you are tired of constantly cleaning your terminals you may want to consider investing in some copper compression terminals. While these are pricier they offer more permanent protection against corrosion than the copper ones.

Preventive measures

Some of the preventive measures that you can try out to prevent the occurrence of terminal corrosion include not overfilling your battery. The battery cells have marks to indicate maximum fluid level. Dry not exceed the levels. Overfilling your battery does not have a positive effect on your battery output – instead it ruins your battery.

Next, try not to overcharge your battery. You should carry a voltmeter to check the recommended voltage of your battery. Again, overcharging does not increase the power output for your battery.

If you are going to be traveling for an extended period, it is prudent that you disconnect the battery terminals. This prevents corrosion and start up problems when you come back. If you have an old car make every effort to replace your battery every five years. There is also an array of anti-corrosion sprays that you can use to keep corrosion at bay.


If you are a new motorist then battery terminal corrosion can be stressing. Firstly, you experience problems starting the car and it can lead to permanent battery damage.

Once you have established that your battery is still in good working condition the next step is to clear out the corrosion with a baking soda solution or soda. Use a soft brush to remove the corrosion as you pour out the baking soda. Next, apply some petroleum jelly on the terminals to prevent further corrosion.