Corrosion of any kind is worrying, but it can seem particularly worrying when it is coming from a battery. Even more so when that battery is in your car!
Battery corrosion, at least on a car battery, can present as a powdery substance. This may be white, blue, or green (or a mixture of all three) and will be found right on the battery terminal.
It can look especially scary when you know that this corrosion is caused by the chemicals inside that battery. I mean, surely that can’t be at all good for your car engine?
Well, if we are being honest…you’re not wrong. Battery corrosion is by no means harmless.
In fact, it could be the reason behind hard starts on your car, battery break down, and engine break down. It can also have an effect on the onboard computer of your car.
Causes of car battery corrosion
There are many different possible causes of a corroded battery on your car. Whatever the issue, it is very important that you replace your battery as soon as you notice any issue with it.
As well as this, it is good practice to check your battery regularly to ensure that any corrosion is caught early before it causes too much damage.
That being said, it is still important that you understand what sorts of issues can cause car battery corrosion, and how to look out for them as well as fix them.
Interestingly, corrosion can appear differently depending on what the cause is, and so, getting to know what causes what type of corrosion is important.
An overfilled battery
If you have a refillable battery, it is important to bear in mind that it can, at times, be overfilled. Typically, these types of batteries will have electrolytes that need to be frequently topped up with water.
This should be done up to the fill line, however, it can be very easy to accidentally pout in a little too much. This is particularly common if the battery is topped up on a hot day as the liquid may expand due to the heat.
Any excess water can then leak out and corrode the metal terminal.
A chemical reaction
The copper clamps connected to the battery are particularly prone to corrosion. The reason for this is not down to the copper itself, but because of sulfuric acid.
Now, I know what you’re thinking…how is sulfuric acid going to be inside your battery or even your car? The answer to this lies in a battery that has leaked.
When a battery leaks, sulfur can be released. This sulfur, upon its release, can react with the current flowing through the copper clamps. This causes a chemical reaction to occur and produces copper sulfate. This copper sulfate can be identified from blue or green colored crystals that form around the battery terminal.
Age of the battery
You can have the best kept battery in the world, but that doesn’t mean a thing when it gets past a certain age. What we mean by this is that, regardless of how well you look after your vehicle and everything in it, batteries do not have an unlimited shelf life. Quite the opposite in fact.
Over time, batteries start to lose quality. After 5 years, it is expected that the terminals of your battery will corrode and that the whole thing will need replacing. 5 years is the typical expectancy of a battery, although it is often much less than this depending on how you maintain it.
Batteries are all about reactions. The reactions inside your battery can produce hydrogen gas. In small quantities, hydrogen gas is completely harmless.
However, when it reacts with other gases this changes. A reaction of hydrogen with another gas, such as sulfate, can cause corrosion. This sort of reaction, spending where it forms, can tell you what the issue is.
If you see the corrosion forming on the positive terminal of the battery, then it is likely that the problem is related to the battery being overcharged. If the corrosion is identified on the negative terminal of the battery then it may be that it is undercharged.
Overcharging the battery
Overcharging your battery, whilst it may seem like you are doing the right thing, can be really bad for your car overall. Think of how hot your phone gets when it has been on charge for a long time. It is the same for your car battery.
The rising temperature inside the battery can cause the electrolytes to expand. The expansion of electrolyte volume puts pressure on the battery, meaning that it will look for a way opulent of it.
This could be through any cracks or vents in the casing. Typically, this occurs in the terminal, causing corrosion around there.
It is possible that, at times, electrolytes could leak out of your battery. Whilst every effort is made to ensure that your battery has a safe, strong, and stable container, sometimes damage can occur to the container, resulting in the insides leaking out.
Of course, for a battery that is well sealed and maintenance free, the chances of this are slim. However, it is not impossible. It is, however, far more common to find this in batteries that require topping up with water.
The electrolyte will be more likely to spill onto the terminals on these types of batteries, leading to a greater risk of corrosion.
What can a corroded battery do to your car?
As we explored in the introduction to the article, a corroded car battery can wreak havoc on your entire car. Even if the corrosion is relatively mild and just on the terminals, it can cause issues such as hard starts, total engine breakdown, and much more.
You may even experience your car just totally cutting out whilst you are driving it. This is, of course, not only completely embarrassing but also dangerous!
Whilst there are times where the only fix is a replacement, you can sometimes fix the issue yourself.
Doing this can preserve the life of your car battery for even longer, provided you identify the issue accordingly and deal with it.
Whatever the cause is for your corroded battery, be sure to treat it promptly, whether that be through simply replacing the battery, addressing the problem that caused it, or cleaning away the corrosion from the terminals. You may even need to do all three.
Keep in mind that whilst cleaning can make it look better, it is still important to establish the underlying cause. It is equally important to clean it using the correct method since the wrong one can exacerbate the issue. In the next section, we will be exploring how you can fix this corrosion.
Fixing your corroded car battery
When your car battery is corroded, it can be difficult to know if you need to replace it or whether you can just clean away the corrosion.
Typically, if the corrosion is on the terminals and you can identify that it is not from a leak, then you can go ahead and clean away the corrosion.
To do this you will need some kind of solvent, and something to scrub with. As well as this, you can also take into consideration a battery cleaning kit. If you do not have a battery cleaning kit to hand there are some household products you can use instead.
As crazy as it sounds, soda can actually be a fantastic product for household use, as well as something tasty to drink. Any soft drink that lists carbonic acid as an ingredient (spoiler alert: most of them do) will be helpful.
All you need to do is apply a small amount to the terminal, focusing on the corrosion. You can then remove it with a soft, dry, clean sponge.
Baking soda and water
Baking soda has long been used as a household cleaning must-have, and when it comes to cleaning up a corroded battery terminal it is no different. This method is best used if the corrosion you have is from copper sulfate.
Before you do anything you should ensure the engine is off, that the ignition is off, and that the car is not warm (give it sufficient cooling time). You simply mix together a small amount of baking soda and water.
You then need to apply it to the corrosion and scrub it using a brush or old toothbrush. After this, you can remove the solution with clean, plain water.
Car battery cleaner
If you have some, you can also use a car battery cleaner to remove any corrosion from the terminals. Permatex has a great one in aerosol form. Simply spray it onto the corrosion, wait three minutes, and wipe it off.
Of course, you should always follow the instructions provided by the cleaner. You can rest assured with this technique that it will definitely be safe for use on a car battery, as this is the purpose it was designed for.
In conclusion, there are a number of things that can cause corrosion on a car battery. All of these things can be easily identified when you know what to look for, and thankfully the answer is not always that you need to totally replace it. Sometimes a simple clean will suffice.
Whether the issue is caused by age, overcharging, overfilling, or a chemical reaction, frequent checks will help you to find any corrosion before it becomes an issue. Remember to follow our guide, and if you are ever unsure, seek help from a professional.