Can you start a car with a bad alternator? [Replied 2022] (2023)

As a car owner, you know how crucial the alternator is in keeping your vehicle's battery charged. As a result, all the components in your car can draw the power they need to function properly.

Have you ever wondered if you can start your car if the alternator breaks? Obviously, I would try to resolve the boot issue as soon as possible. However, if you can't fix your faulty alternator right now, can you still start your car?

We explain whether or not you can start your vehicle with a faulty alternator in this article.

Can you start a car with a bad alternator?

Yes, it is possible to use a faulty alternator to start your car. That way, your vehicle would keep running for some time. You can start the vehicle if the battery is good, no matter how bad the alternator is.

The reason is that the battery would fully support the power requirements of the car if the alternator does not provide the required voltage.

Although a faulty alternator can help you start your car, experts advise against doing so. Only if he decides to drive a short distance can this become a necessity. He must start a car for the discharged battery to start working. So when he starts his car, the battery may already be very low.

Now, the alternator would not give any kind of assistance to the battery. This battery will drain much faster than when you charged it properly. Also, if you have a high electrical load in your car, such as charging a phone, the battery will drain even faster.

So when you remove the jumper cables, the motor doesn't stop immediately. The car would run for so long that the battery voltage wouldn't drop too much. Ultimately, when that happened, the electrical systems would not be working.

How to start a car with a bad alternator?

Even if you have a bad alternator, the process of starting your car would be the same as starting a properly working alternator. However, you have to know the exact process which involves some tricks.

In these situations, it is necessary to keep the cables connected for at least three minutes. Now if you need to drive after starting your car, make sure you charge it for at least 15 minutes.

If not, you have to wait for the battery to drain faster. Since the faulty alternator is no longer supplying the proper voltage to the car, you may be facing some driving hazards.

What to do before starting a vehicle

  • You would need another car's battery to start your vehicle. So be careful that there is no contact between the two cars.
  • Take the keys out of the ignition.
  • On the battery, locate the negative and positive cables.
  • Make sure the staples do not come into contact during this process.

fasten clamps

  • Make a connection between the discharged battery and the positive clamp.
  • Attach the good battery to the other positive clamp.
  • Now place the good battery in the black clamp.
  • Make a connection with the other negative clamp and the head of a bolt, nut, or lime stud.

start your engine

  • Now use the good battery to start the engine.
  • At 2K RPM, start the car for 3 minutes
  • If you want to use the faulty alternator while driving the car, run it for 15 minutes at the same RPM.
  • You may need to run the engine longer if it's cold outside.
  • Try using the faulty alternator to start your car
  • Try a few more minutes if the car won't start

Get rid of the staples

  • First, remove the black clip you attached to the dead battery.
  • Now remove the red claim for the same battery
  • So put aside the positive complaint about the good battery.
  • Lastly, you need to remove the negative clamp that is attached to the good battery.

When you try to start the car with a faulty alternator, be sure to remove all the accessories. This includes air conditioning, heating, CD players, radio, phone charger, GPS, and other components that can rob your battery of power. You would like to retain maximum power so that you can easily start your car with a bad alternator.

Try to do this process when it is dry outside during the day. This ensures that you won't need windshield wipers or headlights, which would help you save battery power. Once you manage to start your car with a bad alternator, try to visit the mechanic as soon as possible and have the alternator fixed.

How do I charge my car battery with a faulty alternator?

If you have a bad alternator, you can charge your car battery by following the steps below.

Paso 1

First of all, you need to start the car. If the battery is discharged, use jumper cables to temporarily charge the battery. Now connect the cables to the vehicle with the engine running and then to the car battery.

The cables must remain connected for a long time (several minutes). During this time, the driver needs to park the vehicle and step on the accelerator. As a result, the battery would have a spike in electricity. Now disconnect the cables as soon as you start the car.

paso 2

Get a portable battery charger for your car and connect it to the battery. Fully charge the charger and make a connection between the positive battery terminal and the red clip.

Connect the negative terminal to the black clip. The strength of your charger largely determines how long it would take for your battery to receive a full charge.

So if you have a 10 amp charger, you can expect the battery to be fully charged in 45 minutes. To get an idea of ​​the specific time, you should consult your charger's manual.

stage 3

Establish a connection between a wall charger and your car battery. This would work if you don't have a portable charger. If it's dry outside, you can also get an extension cord to charge the battery while you're in the car.

You can also remove the battery. Now remove the battery and take it to the charger. Make sure there is a flat surface when charging.

Make a connection between the negative terminal and the black clamp, while the positive terminal remains connected to the red clamp. You will notice that the LED light on the charger turns green when it fully charges the battery.

How long will a car run with a bad alternator?

This largely depends on a number of factors, including the condition of the car's battery, the condition of the alternator, the vehicle's overall electrical load, speed, and the age of the car.

So when you try to drive your car with a bad alternator, it will go 13-15 miles. Approximately, you can ride for 20 minutes after starting the car. However, you can extend this distance if you can keep the RPM low and avoid overspeeding.

In the event that you start your car with a bad alternator while you have a low battery, you should expect it to travel 7-10 miles. This should be equivalent to 10 minutes of driving time.

Disadvantages of starting a car with a bad alternator

With the proper process, neither the donor's nor the recipient's car would be damaged. The process would be safe, but mechanics do not recommend this method for starting a car. When you drive a new car with a faulty alternator, you can't ignore the risk.

The alternator supplies power to all the electrical components in your car.

Therefore, when you start the engine of your car, the battery must receive a full charge to ensure the proper functioning of all these components. So manufacturers design most alternators to put out around 14.5 volts if you have a 12 volt system.

The operation of most components in your car is highly dependent on the alternator. Newer cars, in particular, remain susceptible to the danger of component failure, since they do not prefer low voltages. So the potential dangers of starting your car with a bad alternator include the following.

1. Problems with electric water pumps

Electric water pumps effectively pump water from the car's radiator. This water helps the car run smoothly as it moves through the engine. If the car continues to run even after the water pump fails, you may encounter overheating issues that lead to permanent engine damage.

2. Problems with the power steering

In some vehicles, the power steering is powered by electricity. Without adequate power from the steering pump, you may find it problematic to steer the vehicle. This ends up exposing the car to accident risks, since you would not be able to maneuver the vehicle correctly.

3. Fuel pump problems:

The function of the fuel pump is to supply power to the engine of your car. Even older vehicles have fuel pumps that are powered by electricity. So when the lack of power prevents the fuel pump from supplying adequate fuel to your car engine, it simply stops working.


Starting your car can result in a weird scenario as the vehicle can shut down even if it doesn't sustain any actual damage. So it would be wiser to have your car towed to the mechanic rather than trying to start it with a faulty alternator.

So technically you can start the car even if the alternator is not working. However, it would be wise not to, as you could end up with some sort of component failure in your vehicle.



Will my car still start if the alternator is bad? ›

If your alternator is dead, the car might start but will be running solely on the battery. Can you jumpstart a car with a bad alternator? It is possible in some cases to jumpstart a vehicle that has a faulty alternator, as long as the battery has enough of a charge to keep running.

How do I start my car with a bad alternator? ›

How To Jumpstart A Car With A Bad Alternator
  1. Find Someone with a Good Battery. You can't jumpstart a dead battery without a fully-charged option at your fingertips. ...
  2. Let It Run. Before the jumpstart begins, you'll want to run the other engine for 3 to 4 minutes. ...
  3. Turn Accessories Off. ...
  4. Get Thee to a Mechanic. ...
  5. Use a Jumper Pack.

Will new battery work with bad alternator? ›

If you take your vehicle to an auto parts store they may give you a new battery for a few hundred dollars, without running any tests. Don't make this mistake! A faulty alternator could ruin a perfectly healthy battery, which would put you further back from a solution than where you started.

What happens if alternator fails while driving? ›

What happens when alternator stops working while driving? The car tends to slowly lose power if the alternator has gone bad while the car is being driven. You'll notice the headlights start to dim shortly before the car loses power and dies.

Why won't my car start but I have power? ›

Bad Spark Plugs

If the engine holds compression well, and the fuel system is working correctly, but it still won't start, that tells us that your car's spark plugs may not be working. The spark plugs ignite the air/fuel mixture inside the engine's cylinders. It's the resulting explosion that actually powers your car.

How do you tell if it's a dead battery or alternator? ›

Jumpstart your car. If you can turn the engine on, but it dies shortly thereafter, your car alternator likely isn't able to charge the battery. On the other hand, if you jumpstart the car and later on it fails to start on its own, it's likely a dead battery.

Will your car charge or start with a bad alternator? ›

If the alternator begins to fail, the battery will no longer recharge while the engine is running. Here's how to tell if your alternator is bad. One of the most obvious signs is if the car dies after a jump start. The alternator should provide enough current to keep the vehicle running even with a bad battery.

Can I start without alternator? ›

Yes it can be functional, until it receives the required current for ignition of fuel. It can continue to function until battery drains out or it is getting current from some other alternative source. Can a battery keep up with an alternator?

How far can you drive with bad alternator? ›

This is especially true in newer vehicle models. This is because there is more electricity involved compared to an older model. If your alternator is close to the end of its life, you may only make it a few miles down the street before the battery dies or the vehicle begins to exhibit other electrical issues.


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