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Can You Drive A Car Without A Battery? (Answered)

Can You Drive A Car Without A Battery? (Answered)

Navigating the mechanics of a car can often seem like decoding a foreign language. There are so many questions to ask, like what happens if the rear differential goes out while driving, or is it safe to drive without power steering?

One crucial component that often sparks questions is the car battery. We understand that many drivers wonder about its function, necessity, and potential complications.

You might also wonder whether you can drive a car without a battery

A car might run without a battery, relying on the alternator for power, if the alternator is big enough to carry the vehicle’s electrical needs. However, this is risky and impractical, especially for modern vehicles requiring stable power for their computer systems. You shouldn’t drive without a battery due to potential system failure or damage.

We will address this question in more depth and delve into the crucial role a battery plays in the car’s ecosystem, examining the chemistry, the potential consequences of its absence, and its relationship with the alternator.

In addition, we’ll explore symptoms of a failing battery, how long you can push your car without an alternator, and preventive steps to avoid premature wear of your alternator.

So, fasten your seat belts and gear up for an insightful ride through the world of automobile batteries.

What Is A Battery And What Does It Do?

A vehicle’s battery is a device found in the engine bay and helps start the vehicle.

It provides the electricity needed for the car’s components to work and gets everything roaring to life. The battery also helps in the conversion of chemical energy to electrical energy. In turn, it powers the vehicle and delivers enough energy for you to use in starting the car.

Most battery are comprised of cells.  The cells here are what carry the real energy. For car batteries, they depend on the lead-acid response to start moving things.

These batteries are categorized as SLIs -Starting, Lighting, and Ignition. These battery types deliver a tiny amount of energy to power the car’s light, accessories, and engine.

The minute the battery pushes the engine to life, the alternator generates electricity to replenish the battery once the engine starts and helps power the vehicle’s electrical systems.

How Does A Battery Work

A standard SLI battery consists of six cells, with each cell containing a series of positive and negative plates. One plate is built with lead, while the other is made of lead dioxide. Now each cell can produce, say, 2 volts of energy. Since most car batteries have about six batteries, the battery can deliver 12 volts of power.

These plates are soaked with sulphuric acid, triggering a reaction between them. This sulphuric acid triggers a reaction on the lead dioxide plates and causes the plate to produce two elements. They include ions and lead sulfate. The ions produced react to the other plate to generate hydrogen and lead sulfate.

The aftermath is a chemical reaction that generates electrons. In turn, the electrons move around the plates to generate electricity.  After which electricity leaves the battery airports to turn on the engine, headlights, and radio.

The chemical response is reversible. This is why jump-starting your car is possible, yet the battery can continue charging all through its life. So long you apply the proper current voltage to the battery, lead dioxide, and lead will form on the plates. Hence, you can make use of the battery many times.

Is It Safe To Drive Without A Battery?

Nothing will affect you or put you in danger. But driving without a battery could damage many car electronics and car parts. Running without a battery stresses the alternator and forces it to work more than it’s supposed to.

Please note that the alternator is not designed to power the entire electric system of the car. Instead, its function is to charge your battery.

So even if the alternator can supply the electricity in the absence of the battery, it’s not strong enough the function that way. You might end up blowing up your electronics.

Is It Illegal To Drive Without A Battery?

Most states in the US do not have regulations as regards the use of batteries to drive.

What Can The Alternator Power In A  Car?

The alternator is meant to charge the battery. But if the battery is not present, it does the work of the battery to an extent.

The alternator can supply 14 volts of electricity, so it’s strong enough to carry basic things. Recall that a car’s battery has 12 volts.

Remember, it’s not just about the voltage. The consistent supply and stability of power are crucial, and the alternator doesn’t provide this as reliably as the battery does, especially at idle or low RPMs.

The alternator powers the ignition system and supplies enough electricity to run the radio, headlight, etc. The additional volts of the alternator supply ensure that the battery is fully charged as it’s been used.

So, if there’s no battery, the alternator supplies power to the electrical parts that need it. But this can’t be done for long.

Plus, the risk of running a vehicle’s battery these days is high. That’s because most cars now are built with more electronics than they were before, so you may end up burning a number of car devices and then spend money replacing them.

Should You Drive Without A Battery?

I will be straight here. The fact that everyone does a thing doesn’t mean you should do it.

Yes, you can drive without a battery. But should you do it? The answer is no.

When the battery is out, it forces the alternator to work more than its usual capacity. Most times, When the alternator work to an extent, it gets tired.

It’s either the alternator gets damaged, or it supplies 14 volts directly to the electronics. The engine can handle this voltage, but the electronics may not. This is why most electrical components get blown in the absence of the battery.

The alternator is not designed to power the car’s electrical system but to charge the battery. Using a car part for what is not intended for is dangerous. It’s definitely likely to damage other parts of the vehicle.

Some may even argue that they’ve tried it a couple of times and didn’t experience any surge. See, it takes just one time to get your entire electric system blown out.

As they get burnt, what will you do? You spend money on replacing them. Do you really want that?

Can you Start A Car With An Alternator Instead Of a Battery?

You cannot start a car without a battery and can’t start it with the alternator. But first, note that starting a car and running a car are two different things.

So why can’t you start a car without a battery? The reason is, only the battery stores the right energy to power the engine.

So, if the alternator can power the car and its electrical component as the vehicle runs, why can’t it start the car?

The answer to that question goes back to how the alternator works and its purpose.

The alternator’s job is to convert mechanical energy from the engine to electricity. It just converts but doesn’t store power – the reason why the battery is there.

The work of the batteries is to store enough power the car can use when it’s not running. So that is the only source of power that can help the car start.

So you see, that is why you can’t start an engine without a battery or with a dead battery.

Why Are You Driving Without A Battery?

If you are driving without a battery, it could be that your battery has failed or suddenly died. So what could cause battery failure?

Causes Of Battery Failure

There are several reasons battery dies, and they can be traced to,

Cold Weather

A battery does not have to wait for freezing weather before it dies. Weather at 32° can weaken a battery by 35%. And if the temperature drops to zero degrees, it even drains the battery by 60%

When it’s this weak, even the car’s interior light will be difficult to stay on. And what about starting your engine? Forget it.

One reason most people attribute failing batteries to cold weather is that it’s during this time that a weak battery dies totally.

It is difficult to fix this because you can’t obviously change the weather. What you can do is monitor when the battery is likely to die and make preparation before time.


A battery is made to last for a particular period. When it passes that time, internal materials begin to wear off; most car parts are like that.

Again, the way you use the battery over time can cause it to get weaken and die. The less you drive a car, the higher chances that your battery will wear out quickly. This is because the battery charges with the help of the alternator. And the alternator can only work when the car is running.

However, if you do not drive your cars for long, you can opt for battery tenders. They help keep your battery charged even without moving your vehicle.

You can’t control time, but you can observe how the battery works. This will help you plan.


The battery comes with corrosive acid, yes! But that might not be the problem. A bigger problem will be if there is corrosion at their connections. If the connections are grungy, it may not effectively charge the battery.

Green or blue growth on your battery’s terminal might be an indication that your battery is being damaged by corrosion. Corrosion might also appear like a tiny white substance like dandruff.

While this process might seem natural, it doesn’t help but destroy the battery.

If the corrosion is not much, wipe with a clean, dry rag. If the rag doesn’t help, carefully clean with a hard wire brush. After this, your connections become smooth again, and your battery can charge easily.

Human Errors

One error that you can make us forget to turn off some car parts. Even your headlight can weaken your batteries if you fail to turn it off.

This is coupled with many other things the battery does. The battery supplies electricity to all electrical components in your car. From the radio to headlights and charge your digital devices like phones, tablets, and mobile entertainers on the go. These are good reasons we say your battery overworks itself.

Can you fix this? Maybe, but challenging. Say you remember to turn off your headlights, your anti-theft system and clock still work with the battery.

The battery has a lot of work already, so forgetting to turn off some electronics may be easy to damage the battery.

Electrical Parasite

While this might not be very common, the alternator can be a source of parasitic drain. Your battery depends on the alternator to get charged. If the alternator isn’t working as it’s supposed to, it weakens the battery even in good weather.

A faulty fuse is capable of draining the battery even with your car idle. When it comes to an electrical fault, please reach out to a mechanic.

While the battery’s voltage may not kill you, it may damage your car parts or injure you.

Symptoms Of Battery Failure

You may want to know when your battery is losing its steam

  • Dimming headlights while the car is inactive
  • Ticking or clicking sounds when starting the engine.
  • Engine backfires
  • Engine starts slowly
  • The engine refused to start without you pressing the gas pedal

When you see those signs, it means your battery is on the verge of dying. You can act fast before your car stops abruptly, leaving you stranded.

You might also want to check this informative video that can help you diagnose whether your alternator or battery is failing:

Car Battery Replacement Cost

Battery replacement cost ranges from $45 – $250. But this depends on the battery’s voltage,  size, and quality.

How Long Does A Car Battery Last?

A car battery can last between 3 – 5 years, which also depends on how you use it.

Will My Car Die If I disconnect The Battery?

There are two things you should put in mind when disconnecting the battery. First, is the alternator supplying enough power to charge the battery? Is the alternator good?

If the alternator is intact or can supply enough power to the battery, your car should not die after disconnecting the battery. However, it is hazardous because this action could blow up your car’s electronics. How?

Aside from providing electrical current, the battery helps to control voltage fluctuations. Disconnecting the battery while driving will cause a spike in the alternator’s voltage. This sends a 14 volts current directly to the electronics and causes damage to them.

So, it’s not advisable as it can lead to serious damage!

Can A Car Run Without An Alternator?

The answer is yes, your car will run without an alternator. They are built to run off the smooth 12 volts from the battery. 

Its task is to ensure the battery is charged. So, as long as the battery is charged, the car will run. But ensure you put back the alternator before the engine’s power wears off.

How Long Can You Run A Car Without An Alternator?

Once the alternator is out, the car’s battery will stop receiving the power supply. The battery will run by itself for some time before it runs out of power.

So how long a car runs without an alternator depends on the battery’s capacity. If the battery is not fully charged, it may run within 5 – 30 minutes. However, if it’s fully charged, it can last longer.

Will Your Car Run With A Bad Alternator?

Your car can run with a bad alternator, but there is a catch. The car will run for a short time, plus the power stored in the engine will drain quickly.

How To Detect That Your Alternator Is About To Die

Your car might not run for long without the alternator since the power supplied to the battery will seize.

So you must know when is about to die. Knowing it will save you from getting stranded in a dead car.

The following signs tell if your alternator will die soon. Look out for them.

  • The headlights unexpectedly get dim at night
  •  Alternator suddenly stops working when you use it to charge different electronics at the same time
  • You get to perceive smells of burnt electronics
  • Alternator’s light and other lights turn on
  • The radio and other electronics stop working
  • You may start hearing strange engine noise

How To Prevent Your Alternator From Wearing Off Prematurely

  • Avoid starting your car wrongly. Ensure everything is in place before you start the car
  • Ensure you don’t overload your car with additional electronics. It can damage the alternator
  • Ensure the alternator’s belt is right and the fluid isn’t leaking. Both can damage the alternative direction


While you can drive without your battery, it can cost you a lot.

Driving without a battery stresses your alternator. This is because your alternator isn’t built to power your car electronics. Its job is to ensure your battery remains charged.

The alternator may get damaged if you use it for what it’s not intended for. In other cases, it sends too many volts to the electronics. The spike in voltage can blow up your electronics.

Even if you’ve been running a car without a battery and have experienced no surges, please stop. It only takes one time to get all your electronics destroyed.

The more your electronics get damaged, the more money you spend and it can also lead to some unexpected issues like a hot car key.

Lastly, ensure you look out for bad engine and alternator signs. Both work side-by-side, so even if the alternator is bad, it could affect the battery. Do this so you don’t find yourself stranded on the road because your car suddenly stopped.

If you’ve got more questions then consider checking our articles on whether you can drive a car without a title, or if it’s legal to drive a car without brakes, and many more!

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