What makes car batteries explode? 9 Causes and preventions

By Arif

Testing a car battery

Have you been at the receiving end of a car battery explosion? Do you want to know what makes car batteries explode? If yes, then this is the post to read!

In this post, I will tell you the causes of car battery explosions and the precautions one must practice to avoid long-term damage to the battery and vehicle.

What makes car batteries explode?

A car battery can explode for various reasons and factors prone to human errors and technical faults in the vehicle’s electrical system.

Overcharging and extreme temperatures are the main contributors to car battery explosions.

Some of the other causes include but not limited to are short circuits, loose or dirty battery terminals, clogged vent holes or plugs, bad regulators, physical damages, car crashes, etc.

The causes are too many but to prevent a car battery from exploding it takes simple monitoring and maintenance steps which we will cover below.


Automobile batteries are a combination of water and sulfuric acid which is technically called an electrolyte. This electrolysis process generates hydrogen gases inside car batteries.

When the battery reaches a stage of overcharging the electrolysis process can cause water to break down its elements i.e. hydrogen and oxygen leading to an increased amount of hydrogen gases.

Overcharging sign

A car battery is surrounded by various igniting sources and elements that can raise sparks which may turn into flames when they come in contact with hydrogen gases.

In addition to the hydrogen gas, overcharging can also cause the lead plates of a battery to warp, buckle, or melt thereby damaging its overall structure.

If the battery is left charging for too long at a higher speed, the chances of flames can cause sudden explosions that could be violent and harmful.

The reason behind overcharging can be a human error. Since the process of charging takes long people tend to leave their vehicles on charge for the full night or just forget to disconnect the charger.

Overcharging is often blamed on chargers as well. Incorrect voltage levels and amperage ratings of a charger can lead to wrong anticipations resulting in excessive charging.

Moreover, the charger itself could be the main culprit for overcharging due to its faulty elements and poor charging functionalities.

On the other hand, the wrong connection of the jumper cable could also cause short circuits leading to battery explosion.

It is important to invest in good-quality chargers/jumper cables, plan the charging schedule, monitor the proceedings, and more importantly follow the manufacturer’s instructions for charging a car battery to avoid the risk of overcharging and explosions.

Extremely cold weather conditions

Weather conditions cannot be avoided in car battery explosions. As a matter of fact, extreme heat and freezing cold temperatures have been at the forefront of damaging car batteries.

Coming back to the electrolysis process, when the climate is extremely cold the mixture of sulfuric acid and water freezes. The thickening of these fluids makes it harder for the battery to produce electricity. Freezing is quite common in older batteries especially if they have crossed their age limit.

Secondly, extremely cold temperatures cause the chemical reactions of a car battery to slow down making it lose charge quickly. The hardening of fluids and the impact of chemical reactions could damage the internal components of a car battery.

In such a situation it would be difficult for a car to start and if someone attempts to start it there could be visible sparks due to hydrogen gases released by the battery.

These sparks or flames could ignite an explosion if it comes in contact with another flammable component like cigarette smoke.

Eventually, if the frozen battery is connected to a charger it can potentially explode due to the level of hydrogen buildup inside the battery casing.

To avoid the impacts of cold temperatures it is important to keep a car battery fully charged. Make the effort to park your car in a garage or a sheltered area so that it remains protected from the cold weather.

Leave the car engine running for a while before you begin your journey. Moreover, keep charging equipment’s such as a battery charger/jumper cable in your car to handle dead battery situations.

Significantly hot temperatures

Extreme heat is another instance of car battery failure or explosion. When car batteries are exposed to high temperatures the chemical reaction can accelerate causing the electrolyte fluids to evaporate faster.

The evaporation process leads to corrosion instrumental in damaging or cracking the battery casing and components.

Battery sign on car dashboard

Hot weather can also lead to overheating of battery components. The temperature itself is a major cause of concern that builds up internal pressure inside the battery. This can again rupture the casing and other elements of a battery causing fire and explosion.

It is therefore important to cover your vehicle as much as possible by parking it under the shade in hot weather. Essentially, ensure regular inspection and timely maintenance of the car battery to ensure its holding potential of charging and enhanced lifespan.

Dirty posts and cables

Dirty posts and cables are a result of improper maintenance. Batteries are bound to catch corrosion and rust on the terminals and surrounding cables if no maintenance is performed for a long time or simply because the battery has gone too old.

Corroded battery terminals

The dirt and corrosion are responsible factors for improper connection with the electrical flow which eventually leads to arcing. A similar situation can occur if battery terminals are loosened or arced causing increased levels of hydrogen gases.

Both scenarios carry the risk of sparks and explosions if hydrogen gas is exposed to flammable substances. Moreover, when batteries with dirty posts are charged it can cause severe damage to the internal components due to available hydrogen gases impacting its performance.

As a precautionary measure, always monitor the condition of battery posts and cables. Ensure to perform regular cleaning and substantiate the ventilation of hydrogen gases to avoid an explosion.

Clogged vent holes or plugs

Clogging or blockage in vent holes and plugs raises ventilation issues that can lead to car battery explosion.

If the battery vents or plugs are clogged due to dirt, dust, and debris the hydrogen gases may not be able to escape.

With continuous buildup and increase in hydrogen gas levels, a battery case may rupture or explode causing severe damage to the surrounding electrical components and the vehicle.

The solution to clogged vent holes or plugs is again attributed to timely maintenance. Ensure to monitor and clean the vents and plugs regularly for optimal performance and longevity of a car battery.

Short circuit due to high discharge rate

A car battery is a vital part of every vehicle that provides steady electrical current flow to its electrical system. All the accessories and components of a vehicle depend on this electrical power from a car battery to operate their functions.

A short circuit in the electrical system could accelerate the flow of current to the extent which could be beyond a battery’s capacity. The overflow of current is one of the major concerns for heating the battery components significantly. This excessive heat could ignite the hydrogen gases resulting in an explosion.

It is therefore necessary to use the electrical accessories with caution and maintain the electrical flow to recommended levels. Monitor the faulty and damaged electrical components and perform immediate repairs to avoid short circuits and battery explosion scenarios.

The bad or old regulator

It is a known fact that car batteries take power from an alternator to charge themselves. The alternator has a voltage component called the regulator that actually regulates the charging power.

If the regulator is in bad shape or too old to control the voltage power it can lead to overcharging scenarios. As mentioned earlier, overcharging is responsible for electrolyte liquid boiling resulting in the release of hydrogen gases.

Old car alternator

The combination of overcharging and hydrogen gas is enough to create a potentially explosive environment.

While you can rely on an alternator to take care of your vehicle’s battery power it is important on your part to take care of the alternator.

Checking the alternator and identifying a bad regulator should be part of your routine maintenance monitoring. If you find the regulator is not working up to its potential get it repaired or replaced immediately to prevent battery explosions.

Car crash/accident

A car crash/accident is more than just bothering about the battery however it remains one of the crucial parts between minor and significant damage to you and your vehicle.

During the crash, if the metal parts of a car such as an engine block or other electrical components come in contact with the battery it can create a spark or a short circuit.

The situation could turn explosive if these sparks clash with already heating parts of a vehicle due to a crash.

While you can’t do much except panic nonetheless keeping the car battery properly maintained and securely mounted could reduce or limit the impact during a crash.

Always check the tightness of poles/terminals, and vents, and ensure the battery is correctly positioned. To be on the safer side, keep the battery under cover to protect its flammable liquids from spilling and catching fire.

The age factor

It is important to keep a tab on the age factor of your car battery. Keeping the external causes aside, if the battery has crossed its recommended age limit there is no doubt it can fail to function and may start leaking its liquid.

As the battery ages, it can start to develop internal cracks and defects leading the flammable hydrogen gases to buildup. If the battery is not repaired or replaced on time the hydrogen gases can spill out through the cracks and mix up with other ignitable parts of a vehicle to catch fire.

Make sure to invest your time in inspecting the condition of your car battery regularly and if there are signs of leakages or cracks because of aging get it replaced immediately.

Can a car battery randomly explode?

Car batteries don’t randomly explode on their own unless prompted by various technical factors and human errors.

It is a rare scenario but cannot be eliminated because of the elements and components a car battery is made of.

Lead acid batteries which are quite common in many old and new vehicles are prone to an explosion due to improper maintenance, wrong handling, manufacturing defects, and aging.

Many modern companies equip their vehicles with sealed gel batteries that are protected from explosions caused by chemical reactions. There is no availability of hydrogen gases in such batteries so there is hardly any risk of explosion.

Can a battery explode while driving?

In general, the car battery exploding while driving is low but in rare scenarios, it can happen. Poor maintenance can lead to corrosion and rust on battery terminals which can limit the current flow.

Lack of current flow increases the pressure on the battery to perform beyond its limit causing a buildup of hydrogen gases. Hydrogen gases can transform into explosions if they come in contact with other heated parts of a car while driving.

Similarly, if the battery has signs of cracks or damage that are ignored for a long time it may release unwanted liquid to other parts of the vehicle causing sparks and explosions while driving.

Extreme weather conditions and poor ventilation are some of the other causes that can impact the performance of a car battery regardless of its standing or driving situation.

What to do when your car battery explodes?

When you actually face a car battery explosion here are the things to do:

First of all, do not panic. Stay calm and composed.

Next, take your car to the side of the road or to a safe location away from the moving traffic or residential areas. This also depends on the condition of your vehicle after the explosion. If the car is movable proceed with this step otherwise leave it as it is and cover the vehicle with hazard signboards to protect others.

Ensure to turn off the engine. It is the hood that will be under fire and keeping the car and other electrical components ‘on’ could exaggerate the fire.

If you are confident enough open the hood to check the condition inside. Make sure to wear protective glasses and gloves before touching anything as you may have to deal with lots of liquids and chemicals that could be harmful.

If you find the situation favorable, attempt to disconnect the battery cables. This is not recommended if you are not familiar with the process. Leave the connection as it is and try to clean the surrounding area with a cloth. Make use of baking soda and water if available.

Leave the car windows open if you find gases or fumes inside the vehicle. Lastly, call for vehicle assistance and follow the guidelines from the team to remain protected till they arrive.

How do you prevent car battery explosions?

Battery explosions can be prevented primarily with proper maintenance. Regularly maintaining the car battery helps avoid corrosion and keeps them clean and tight.

This will also avoid the risk of loose connections and arcing. Cleaning the battery periodically helps improve the ventilation required for proper functioning.

Secondly, with a timely inspection, you will be able to spot the signs of any damage, cracks, or leaks in the battery case which can be taken care of during maintenance.

Take utmost care while charging the battery. Use a battery charger of high-quality that is compatible and has fast charging functionality. Monitor the charging process to avoid an overcharging situation that could eventually lead to explosions.

While jump starting, ensure proper connection of cables on both car batteries. Use a jumper cable of good quality and perform the jump-starting process with caution following jump-starting guidelines to avoid sparks and battery explosion.

Final thoughts

A car battery explosion is a serious issue that many motorists avoid due to negligence or overconfidence.

There are various signs and warnings of a car battery that is vulnerable to an explosion. It is important to remain alert and identify them for timely action.

A majority of car batteries explode due to overcharging and poor maintenance. Both issues are manageable with proper caution and pro-activeness.

We have seen the causes in detail and also the precautions and remedies one can take to avoid car battery explosions.

Keep your vehicle always maintained, give special attention to a car battery, and ensure to carry useful accessories such as a battery charger/jumper cable to handle and counter any battery issues on the way.

Rest assured I am sure you will remain safe and protected by reading and following the information in this post on car batteries.

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I am the founder of TheCarPlus. As a passionate car owner and enthusiast, I offer practical solutions and insights from my own personal experiences combined with extensive online research.

The purpose of creating this website is to empower fellow car owners and motorcyclists like 'YOU' with knowledge and practical solutions to enhance your vehicle's performance and aesthetics.

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