Car Battery Leaking From Top? Here’s What You Should Know

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It’s called sweating. Your car battery is covered with drops and eventually, it turns into a hard substance.

What is it and what are you supposed to do about it? Don’t panic. These guidelines will help you.

So here are the facts to know when your car battery is leaking from the top.

Is a sweating battery dangerous?

The short answer is yes. Below you’ll see many reasons for a battery’s leaking.

Some circumstances are vital to tend to. Firstly, you don’t want your car to suffer damage, right? But your own safety is also important. Don’t get stranded beside the road and don’t let an electric problem cause hazards in your garage.

Is it normal that new batteries leak?

New batteries aren’t supposed to leak, but accidental tipping can cause it.

It should subside eventually as the liquids settle again. If it continues, your battery is probably faulty and you should exchange it.


battery leaking

​When a car battery leaks acid, it is usually through the cell caps on the top of the battery, or due to damage to the body. Overcharging your car’s battery is another reason for leakage. Smart battery chargers detect and give signals to show when a battery is charged to full capacity to avoid this.

​Here are some more problems often people encounter

Rapid charging:

Your alternator connects with your battery and determines the number of volts—the amount of power—that is generated. But the alternator and specifically the regulator can malfunction.

When too much power is sent through, it can cause rapid charging. This will make the liquid inside the battery—water and acid—bubble and exit the unit.

Overfilled battery chambers:

This same liquid needs to be monitored well. New batteries rarely require filling up, but occasionally it can be necessary. Older batteries need regular replenishment of distilled water. Don’t add acid as you may impair the battery’s functioning.

Whenever filling up is required, you risk of letting the chambers overflow. Follow directions and if you did add too much, tip out the excess.

Luckily, this problem can easily be fixed and it shouldn’t damage the battery. The only risk is corrosion of the exterior parts of the acid or water lies on top for too long. Check your battery regularly so you can clean it when necessary.

Expanding plates:

Heat can make your battery parts expand. Though this is a rare occurrence it can push the liquid out of the battery.

Of course, these changes mean your battery might now be damaged. It’s best to replace it.

Did you tip it?:

Batteries should be kept upright. When you tip one you can cause liquid to escape. A battery’s chambers can’t be completely sealed because the chemical reactions produce hydrogen gas. This will cause pressure on the battery. For this reason, each battery has vents.

Tipping is not a dire problem. A few drops that escape won’t affect the battery’s functioning too much. You can also remedy the problem by adding distilled water.

A Cracked Battery:

The liquid can purely bubble out because of cracks in the casing. This could be because of pressure building inside or driving over rough terrain.

Debris or excessive shaking inside the engine can cause cracks. It’s uncommon but possible.

This is one of the reasons you must regularly check the inside of your engine.

A number of problems can occur and you may not know until it’s too late.

Cracked Battery

Cold climate:

Here’s another cause that’s not very likely, but you never know how the weather’s going to turn, and the liquid in your battery can freeze in the excessive cold.

Freezing means expansion. The contents of the battery will press the casing’s sides outward, and this creates pressure on the cells. Now you have leaking cells and you’ll know about it when you see the sweating battery.

It’s better to pick up on this problem before it gets to this point. You definitely don’t want to handle this problem besides the road. If you realize the temperature has dropped considerably overnight, it’s best to check your battery before your next trip.

Here’s a good selection of winter batteries. Check it out!

Old age:

There’s a reason batteries are sold with limited warranties and guarantees. Even though you can maintain a battery by adding more fluid they’re not designed to last forever.

Signs of Car Battery Leakage

Some signs can indicate acid leakage in your car’s batteries. First, if a rotten egg smell comes from your car, this might mean it’s time to change your batteries. 

Another thing to check is battery corrosion around the battery terminal cabs. 

In addition, if your car’s battery casing looks swollen, warped, or bloated, this might mean there is some pressure brought about by the battery acid that is causing the casing to bloat. 

Moreover, if you notice that your car batteries are wet or sweating, this might indicate some leakage of the sulfuric acid, which is a component found in the solution of water in the battery. This is why you should not touch the contents of the car battery. 

How Do I Dispose Of A Leaking Car Battery?

We recommend battery replacement every 3 to four years. This is because overuse of batteries is one of the causes of leaky car batteries. 

When you have dead car batteries, you cannot dispose of them in your trash can. This is because acid and lead are harmful to the environment and wildlife. Instead, the safest option is to take them to the workshop where you had your dead battery replaced.  

On the other hand, you can look for the local recycling center near you as they help recycle bad batteries. You can also look up other workshops that do replacement battery services and dispose of damaged, old battery cells for a fee. 

Battery fluid levels that are consistently low are another symptom of a leaking car battery. This is especially true when you fill your car battery, and you realize that the levels are low after some time. 

You should also look for a bubbly liquid seeping through a vent cap. The bubbly liquid is caused by the reaction of sulphuric acid, causing the acid leaks in the vent cap.


The act of lead sulfate crystals forming on the battery plate’s surface is known as sulfation. Excessive sulfation may increase the chances of acid boiling over, spilling sulfuric acid solution inside the battery. 

Now let’s look at battery symptoms that may indicate acid leakage. 

What Are The Symptoms of Leaky Car Batteries?

Symptoms of car battery leaking may include:

  • A bubbling liquid oozing through the vent caps
  • A warped or bloated battery casing
  • The presence of a rotten egg smell coming from a sulfuric battery solution
  • The battery fluid levels are frequently low despite being filled up recently
  • Corroded battery terminal caps
  • A sweating car battery 

You should consider battery replacement if your battery is giving off any of the signs above.

Is A Leaking Car Battery Dangerous?

Yes, it’s dangerous. A car battery contains acidic content. Acid is corrosive and can irritate the skin, damage clothing, and, if left uncleaned, can lead to metallic corrosion. The battery also produces hydrogen gas which is highly flammable and volatile. Any excessive buildup endangers your life and your car.

What Type of Fluid Does A Car Battery Leak?

The component of a car’s lead-acid battery is a solution of sulfuric acid in water. So if the car battery is leaking, can that liquid be acid? Yes, it definitely is! When it’s not acid, it can be an overflow of distilled water caused by overfilling.

What to Do If Your Car Battery Leaks?

The first thing is to refrain from touching the components of the leaking battery and put a plan in motion to change it soonest possible. If your car is having trouble starting, don’t be quick to jump-start it with jumper cables while there’s a leak. Sparks can ignite the volatile gases coming from the battery and induce an explosion.

So what is an easy fix to your problem?

Keeping a bad battery in the car is dangerous for the vehicle, and it also poses a potential hazard to your health. Replacing that battery as soon as possible is the safest option. Ask a professional mechanic to come where you are instead of driving with a bad car battery. 


A battery’s performance should guide you as to when you replace one, but after four or five years, you’re driving with a very unreliable engine part. It can cause problems at any moment and leaking is one of them.

I hope this post has helped you to recognise and avoid potentially dangerous leaks from the top of your car’s battery

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Car Battery Leaking From Top? Here's What You Should Know
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21 thoughts on “Car Battery Leaking From Top? Here’s What You Should Know”

  1. Had to get my car jumped this morning battery was leaking out top post started sparking hope I didn’t ruin anything else in the car help needed

    • Mine went dead and wouldn’t charge. 1st cell was dry. Pulled it out and took it where I bought it. It was only 32 months old
      The guy said it leaked all the fluid out around the post and got a new pro-rated battery. Still costed $108.80 but that was better than $168.00 for a new one without warranty.

  2. If 5 year old car battery is getting corrosion on the positive terminal, should I think about replacing the battery? I am worried about getting stranded.

  3. Yust went took battery off charger noticed it was leaking a little bit not much at all though does this mean its no good an i sbouldd not use

    • Was it a lead acid battery? the ones with removable caps? If so, you need to take the caps off when you charge the battery. If the caps weren’t removable maybe you charged it for too long

  4. I hit my bumper on a medium and it came loose. The day after the repair shop showed me my Exide battery was leaking acid into interior car parts resulting in my car being totaled. Can the accident have caused the battery to leak acid?

    • Hard to tell, If I had a picture of the crash outcome maybe, but there’s a chance if the crash was big enough that some metal piece punctured the battery (but lemme tell you that’s really friggin hard). Then that’d make sense. Otherwise a moderate crash shouldn’t affect the battery at all and there’s a chance the battery had been leaking for a long time already. It just happened to be unveiled after the crash but no correlation.

  5. My battery is only about 5 or 6 mo. old and has been working fine until now. I sometimes only drive once a week with no problems. I just changed the harmonic ballancer, water pump, and belts on my ’90 Corolla then a few days later the battery was dead. It seems I now have a short somewhere. After charging & leaving the bat disconnected over night it holds a charge fine, but when I plugged in the bat & started it up, it was charging at 16.68v and the water was spilling over.
    Any idea what happened?
    Does the alt. need replacing now?

    • It depends on where your voltage regulator is, some are built into or on the side of the alt. Some are separate. Your charging system definitely has a problem. If at your BATTERY. You are reading over 16vdc. It really depends on your vehicle but 99% of the time all secondary systems powered by the alt. Will be 14vdc or lower. If your reading the alt. In a “no load” state it may also appear to be higher vdc than what it delivers to the battery. There may be a shunt or some other device used for knocking down your charging voltage. Take the vehicle to the parts store and let them test the alt. And battery.

  6. I bought a new battery but when i was going hme it failed down and crecked on top near positive terminal, is it necessary to use it or to replace it

  7. They just make things to last about as long as the warranty, if it last that long consider yoself luck because I ha both mine replaced in warranty before and guess the one I just took in was under warranty and messed up again. The manufacturers could care less the could make them better,more dependable and last a lot longer but they choose not to to create problems thinking most people will take the vehicle in to get it checked out and believe me they will try very hard to blame it on other things just to sell and charge a repair charge. They will try to blame the alternator,regulatoror something else. The will really prey on women so be careful!!#

  8. Never expect auto parts especially batteries to last as long they are suppose to. The manufacturer knows exactly how to make things to last just long enough to meet the warranty. You can also bet they could build them better to last longer but that takes money out of their pocket through buying and or charges in repairs. A bad battery can make your alternator work extra hard causing it to go out. Guess what then they get to sell you an alternator plus mechanic fees which are OUTRAGEOUS.

  9. I have an RV with 2 batteries. I noticed One will leak from the vent in the cap .
    While charging it is putting 13.4 volts in to the battery .
    Is that too much voltage ? Is it overcharging the battery?

  10. This just happened to me. About quarter cup leaked out . Wilk the battery still be usable after its cleaned up

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