Car Battery Leaking Acid From Top? Causes and Solutions

Are you noticing that your car battery is leaking? That’s not at all a safe condition to be in? If you notice the hazardous situation, car battery leaking acid from top, you have to act ASAP. Just leaving it be would get you into more trouble and can cause your car irreversible damage. This article discusses the various causes and solutions of such an issue so read on!

Why Is My Car Battery Leaking Acid From Top?

Before going further into the article, you should know why your car battery may be leaking. Car battery leaking acid from top is not a very common condition. It is rare and when it happens it is a real safety hazard. Here are some reasons why your car battery can leak from the top so read on!

1. An Overcharged Battery

One of the most common reasons why you have to face the issue, car battery leaking acid from top will be an overcharged battery. When your car battery is overcharged, the electrolyte in the battery starts boiling. This will cause the acidic steam to flow out of the vent caps. Along with leaking, you would be able to see steam pools on the surface of the battery, making the unit look like sweating.

The acid then contaminates the metal parts of the battery causing the battery to corrode. This is one of the easiest ways that leads to battery corrosion. In more extreme cases, the gases in the battery can build up and even cause it to burst. Thus ignoring car battery leaks can be more harmful to your car.

What Causes Overcharging?

The most probable reason for car battery overcharging is a malfunctioning alternator in the charging system of the car. Some car batteries have smart battery chargers which can detect when your car is in full capacity and stops charging.

2. Old Battery

Most items are prone to get worn out and damaged with age. This is the case with car batteries too. The longer a car battery is used, the less reliable it becomes and the more prone it is to leakage. Car batteries typically last around 4 years on average, though the lithium battery in hybrid vehicles is designed to last longer. After it has lived its capability, the old car battery becomes prone to leakage.

3. Overfilled Battery Chambers

Another reason that can cause the situation, car battery leaking acid from top, will be overfilled battery chambers. Car batteries need a distilled water refill now and then unless your battery is maintenance-free. However, if your battery is overfilled with water, it will overflow along with the acids and spill.

4. A Cracked Battery

Excessive shaking of your car battery can cause cracks in your battery. Sometimes the battery may not be secured correctly in its loose brackets. The chemical reaction in the battery can also cause it to bloat, developing cracks, out of which the electrolyte solution can seep through.

5. The Battery Was Tipped

The chemical reaction inside your car battery produces hydrogen gas which needs to be vented out. This is one of the reasons why your lead-acid car battery cannot be fully sealed. If your car battery is mounted at an angle accidentally tipped over, the electrolyte solution inside will spill over each battery cell and possibly out of the vent cap. If left in this condition, the battery cells can dry out and short, reducing your battery’s lifespan and efficiency and also cause it to leak acids from the top.

6. Battery Plate Expansion

Engine temperature getting hot, excessive heat formation due to overcharging, etc will cause your car battery plates to expand. This is a very rare scenario but when this happens, the electrolyte solution in the battery will forcefully be pushed out and as a result the battery leaks.

7. Exposure To Extreme Cold Weather

Cold weather and car batteries are no friends. The fluid inside the batteries tends to get frozen when exposed to frigid temperatures. This would create pressure inside the battery which pushes the battery casing outward. If the pressure continually builds, the outer surface of the battery finally cracks causing acid leaks.

8. Sulfation

Sometimes sulfate crystals form on the surface of the car battery plates. In cases of extreme sulfation, the chances of extreme sulfation is an increased possibility. This would result in the spilling of sulfuric acid solution out of the battery.

Is It Dangerous To Have A Leaking Car Battery?

It is extremely dangerous to have a leaking car battery. The electrolyte solution or the battery fluid inside the battery is acidic. Acid is corrosive and can make many surfaces like battery parts, clothes, etc. corrode. Acids can irritate the skin and cause metallic corrosion if it’s left uncleaned.

The hydrogen gas that is produced in the battery will come out if there are leaks that are highly flammable and volatile. An excessive buildup of hydrogen gas puts the life of both you and your car at risk.

What Should I Do If I Notice My Car Battery Leaking?

The first thing you have to know if you see your car battery leaking is to not touch the acid coming out from the top. You have to take the necessary steps to replace the battery ASAP.

If your car doesn’t start, do not attempt to jump start it when your car battery is leaking. The sparks might end up igniting the volatile gases coming from the battery which would lead to an explosion.

The safest option for you is to get your car battery replaced as soon as possible. But never attempt to drive your car with a leaking car battery. Get a mechanic to do the work and get your car battery replaced.


Your car battery leaking acids and letting out volatile gases like hydrogen gas out is not at all a safe condition to be in. It is a very dangerous safety hazard and the situation must be handled very carefully. Get your trusted mechanic immediately to get your car battery replaced and make sure to wipe out any acid spills with utmost care and safety. Hope you found this article helpful!

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