Car Battery Hissing – What Should I Do To Fix It In 2024

Experiencing hissing sounds from my car battery was perplexing and raised concerns. Determining the source of the hissing and finding a solution became a priority. I researched possible causes and learned effective steps to address the issue, ensuring my vehicle’s optimal performance and safety.

Car battery making hissing noise? (Short Answer)

When a car battery has been overcharged, and too much air has built up inside, it will hiss. This can happen if the battery charger is too big or the generator isn’t working correctly. A car battery will die if nothing is done to stop the hissing.

This article does a great job of educating drivers about what causes why is my battery hiss and how to stop it.

What Are The Causes Behind Car Battery Hissing?

That hissing is hydrogen gas leaking out. One spark and you will have an explosion. It’s probably caused by grossly overcharging the battery.

Causes Behind Car Battery Hissing

Experiencing hissing sounds from a car battery can be disconcerting, and when I faced this issue, I delved into understanding the potential causes. Here are some reasons behind car battery hissing:

1. Overcharging:

Why is my car hissing? A car battery hissing while charging can signal that the battery is overcharging. Overcharging occurs when the battery receives too much charge from the alternator or charger. It can cause the acid inside the battery to degrade, resulting in hydrogen gas leaking and making a hissing sound.

Why is my battery overcharging? The main reasons for overcharging are:

  • Using a charger that is too big
  • Not using a smart charger or leaving a charger on your battery for too long.
  • One or more bad cells in the battery
  • If the car’s charger (or any other part of the charging system) doesn’t work, the battery won’t charge.
Source: center.meineke

Generally, it would be best to use a charger whose amps are 10% or less of your battery’s total amp hour value—the chance of overcharging your battery increases when you go over that voltage.

Also Read: What RPM To Charge Car Battery

2. Over-sized Chargers:

As I said before, using a too-big charger for your battery will overcharge. Keep the amps of your battery charger at 10% or less of your car battery’s total capacity.

For instance, if you have a 70 amp hour battery, you shouldn’t use more than 6 to 8 amps. Since 10 amp Chargers are so popular at big box stores, I know many people have them.

If you have one of these, just be extra careful when using it on a battery that doesn’t quite hit 100 amp-hours. If the battery hisses, bubbles too much, or smells like rotten eggs, unplug it and choose a smaller one.

Source: machinemart

Also Read: Car Battery Doesn’t Fit In Tray

3. Leaving a Charger Hooked up for Too Long:

Your battery may also hiss if a charger is connected for an excessively extended period. This won’t be a problem if you use a contemporary, microprocessor-driven smart charger that switches to “float” or “maintenance” mode.

Source: shrinkthatfootprint

The battery will hiss and experience higher pressure buildup if your old-school charger is just 10 amps and the battery is charged to 100%. These 10 amps will continue going through the electrolysis process we discussed earlier.

4. Air Circulation:

Another reason for a hissing sound from a car battery can be the release of hydrogen gas through the ventilation system. When a battery produces more hydrogen gas than it can hold, it can leak through the vents designed to relieve internal pressure.

Air Circulation:

5. Overheating:

An overheating battery can also cause a hissing sound. Overheating happens when the battery produces more heat than it can handle, causing the casing to expand and hiss.

Overheating car battery

Many factors, including temperature, overcharging or discharging, or an issue with the battery’s charging system, can cause a battery to overheat.

Also Read: Car Dies When Removing Positive Battery Cable

6. Destruction:

In some cases, a hissing sound from a car battery can result from the internal parts degrading over time. The electrolytic water, which is the fluid that provides the conducting atmosphere for the battery’s chemical processes, might start to leak as the battery ages due to the internal portions of the battery beginning to degrade.

7. Malfunction Car’s Alternator (or Charging System)

Finally, you should have your alternator and the rest of the vehicle’s charging system inspected by a qualified mechanic if you hear the hissing when the battery is connected under the hood.

Generally, your alternator’s charging voltage will be about 14.1 or 14.2, but it may rise to 14.8 or even higher in colder temperatures.

The Dangers Of Car Battery Hissing:

Are batteries still good? Hissing and leaking out: While a hissing car battery is not always a cause for alarm, Understanding the risks that could result from the issue is still crucial:

dange of car battery hissing

1. Fire Hazard:

Is a hissing car battery dangerous? One of the most serious dangers of a hissing car battery is fire. It can occur if the battery produces less power, resulting in shorter battery life.

2. Acid Leakage:

Another danger of a hissing car battery is acid leakage. It can occur if the casing is damaged or the battery produces more acid than it can contain.

Acid Leakage:

3. Reduced Battery Performance:

A hissing car battery can also lead to reduced battery performance. It can occur if the battery produces less power, resulting in shorter battery life.

Also Read: How Far Can A Car Drive On Battery Only

What You Should do if your Battery is Hissing?

Put on some safety glasses before approaching the charging source and turning it off or unplugging it if your battery is hissing while charging. Just lock the door and turn the key. Remove the charger from the wall if it is one.

While the charger is plugged in, do not disconnect the cords from the battery! The last thing we want is a spark when you disconnect the charging connections since many of the gases the battery is leaking out and hissing are combustible.

Source: repairsmith

Most smart chargers will claim that they won’t spark on a battery terminal, but why run the risk of getting skin burns, going blind, or even worse? After charging, give the battery 30 to 60 minutes to stabilize.

How to Avoid Car Battery Hissing?

1. Avoid Overcharging:

Car battery hissing when charging? Another effective method of preventing a hissing car battery is to avoid overcharging the battery. Avoiding overcharging can be accomplished by utilizing an excellent battery charger.

Avoid Overcharging:

Also Read: Car Making Noise After Battery Change

2. Keep The Battery Cool:

Keeping the battery cold is critical because it can hiss if it overheats. It can be done by ensuring the battery is in proper air circulation and keeping the car’s electrical system clean.

3. Replace The Battery:

  • Take action if the car battery is showing signs of destruction.
  • Additionally, replacement may be necessary if it is releasing a hissing sound.
  • To prevent further problems, replace the battery immediately.
  • Ensure the safety and performance of your car by addressing any battery issues.
  • Furthermore, a replacement may be the best solution for a hissing car battery.
Replace The Battery:

Also Read: How Long Does It Take To Change A Car Battery

battery charger makes hissing noise:

Encountering a hissing noise from a battery charger can be concerning. When I faced this issue, I quickly investigated possible causes.

Hissing may result from a damaged transformer, loose components, or excessive electrical current. It’s crucial to identify and address the source promptly to ensure the safe operation of the charger and prevent potential hazards.

How Do You Find Your Car Battery’s Amp-Hours (AH) to Size Your Charger Properly?

Most car batteries are measured in cold cranking amps (CCA) or reserve capacity (RC), not amp hours. If that’s the case with your battery, I have some easy-to-use tools right below this where you can type in the numbers from the sticker on your battery to find out how many amp hours that is.

Source: carsguide

If you know the cold cranking amps, you can type them into the first calculator and immediately see the answer.

Use the second calculator if your reserve capacity is set at 25 amps or if the amps are not listed after the reserve capacity time. Use the third calculator if your battery has a spare capacity time and an amperage of 25.

Also Read: The Car Battery Has Voltage But No Amps

1. Is A Hissing Sound From A Car Battery A Serious Issue?

Take notice if you hear a hissing sound from your car battery. Although it may not always indicate a dangerous problem, it’s still important to address it immediately. The hydrogen gas released from the battery is highly flammable.

2. Can A Hissing Sound From A Car Battery Cause Damage To My Car?

A car battery that hisses can become damaged and have a shorter lifespan. The highly flammable hydrogen gas generated from the battery might pose a safety risk if left unchecked.

3. Can A Hissing Car Battery Explode?

A hissing car battery can release hydrogen gas, which is flammable and explosive. However, the likelihood of an explosion is low as long as the battery is undamaged and well-ventilated.

4. How Long Does A Hissing Car Battery Last?

The lifespan of a hissing car battery can change depending on the cause of the hissing sound. Sometimes, a hissing car battery may function for a few days or weeks but also fail in other situations.

5. Why is the Lithium Battery Making Noise While Charging?

Lithium battery hissing? No, a lithium battery does not make a hissing sound. If they do, they are likely about to detonate, catch fire, or experience some sudden failure. You could still remove the battery from a gadget if it is inside. Get the car outside as soon as possible if the battery is hot or you can’t remove it.

6. What To Do When Battery Hissing And Leaking?

The hissing sound is hydrogen gas escaping. An explosion can be started by just one spark. Very likely a result of seriously overcharging the battery. Get a new battery to avoid further loss.

7. Can I continue using a car battery that occasionally hisses?

It’s not advisable. Any abnormal hissing indicates a potential issue, and continued use may lead to battery damage or safety hazards. Consult a professional to determine the cause and necessary steps for resolution.

8. Can a hissing car battery damage other vehicle components?

Yes, a hissing car battery can damage surrounding components due to overcharging or venting issues. The corrosive nature of the released gases may impact nearby electrical and metal parts.

9. Can a car battery hiss after jump-starting?

Yes, it’s possible. After jump-starting, the charging process might cause a temporary hissing sound. However, further investigation is needed if the hissing persists or is accompanied by other issues.

10. Can a car battery hiss even if it’s relatively new?

Yes, though uncommon, new batteries may develop issues. If a new battery exhibits hissing, it could be a manufacturing defect or a result of improper charging. Warranty coverage should be checked, and professional assessment is advisable.


In my experience, addressing a hissing sound from the car battery requires swift action. Confirm if the battery is overcharging by checking the voltage and replacing the regulator if needed. Overcharging poses risks, including damage to the battery and the release of flammable hydrogen gas. Prioritize immediate resolution for the safety of your vehicle and its passengers.

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