Can You Jumpstart a Car With a Bad Alternator?

Your car won’t start if the battery is dead or the alternator is bad. It’s easy to recharge a dead battery, but replacing a bad alternator is very expensive. If you don’t have the money, can you jumpstart a car with a bad alternator?

You can jumpstart your car even if the alternator has gone bad. If the battery is still good, you can keep your car running for some time. Your car will run purely from the power of the battery. However, this won’t be for long because the battery will soon run out of its juices.

How can you tell if the alternator has failed and not the battery? If you can start the engine but die soon after, the alternator cannot keep the battery charged. It is the one that has gone bad and not the battery. If it’s the battery’s fault, you won’t be able to start the engine in the first place.

Read on to learn more about why you can jumpstart your car even if its alternator has gone bad and how you can do it.

Can You Jumpstart a Car With a Bad Alternator?

can you jumpstart a car with a bad alternator

Yes, it is possible to jumpstart your car even if the alternator has completely failed. You can keep your car running no matter what happens to the alternator. When this happens, your car will be running entirely from the electricity supplied by the battery.

You can tell if the alternator has failed and not the battery. If you can start your car when you click the ignition, but the engine dies immediately, then the battery is good, but the alternator is bad.

The primary job of the alternator is to keep the battery charged. So, if your car starts but dies off soon after, the alternator cannot charge the battery.

And since the battery is the only one supplying power to run the engine, the engine dies soon after it starts because it has already run out of juices. If the battery is the problem, you won’t be able to crank the engine in the first place.

So, you can start your car even if its alternator has gone bad. But it will eventually die since your battery has a limited capacity. If your battery is not fully charged, you can expect your car to be able to run only for about 5 to 30 minutes.

Can You Keep Driving a Car with a Bad Alternator?

Not Recommended

Can you drive a car with a bad alternator? Running a car with a bad alternator is not recommended. However, if it happens suddenly while you are on a trip, you can still drive your car.

It should only be for a short drive that will take you to the nearest car repair shop so you can have it examined by a mechanic.

Jumpstart the Car

You can jumpstart your car if the alternator is not working. Can you jumpstart a car with a bad starter? Yes, you also can. But when you drive your car, the battery will not be getting the charging that it normally gets from the alternator.

So, jumpstarting your car will only help the battery for some time. The battery cannot sustain the power needed to reach your intended destination.

Depends on the Battery’s Charge Level

But it doesn’t mean that if the alternator has failed, you won’t be able to start your engine. It depends on the charge level of your battery. As long as it is fully charged, you can run the engine for some time, but not for long.

Your car has many electrical components that make it run. All of these components use electricity to make your car safe to drive. It is the alternator that helps the battery to supply the electricity requirements of all these components.

So, if the alternator has completely failed, it won’t be able to keep the battery fully charged. And when all the electricity requirements are supplied by the battery, with no help from the alternator, your car will stop, simply because the battery has already lost all its juices.

Replace the Alternator

If you have encountered this problem, the best solution is to replace the bad alternator with a brand new one. You can’t continue driving your car with a bad alternator unless you want this problem to crop up, again and again.

What Happens When Alternator Goes Bad While Driving?

Jumpstarting a car with a bad alternator carries with it some risks. It won’t necessarily destroy your car, but there are some dangers that you need to be aware of. Driving with a bad alternator poses some danger.

It is the alternator that powers all electrical devices your car uses, including:

  • Lights,
  • Air conditioning,
  • Radio,
  • Power steering, and many more.

And when you turn on the ignition, the alternator also generates around 14.5 volts that your car’s 12-volt electrical system needs.

So, you can’t imagine how important the role of an alternator is in the perfect running of your vehicle, especially if it’s the latest model. If the alternator has gone bad, it won’t be able to fulfill its most important duties in running your car smoothly.

The following things can happen if you drive a car with a completely failed alternator:

1. Fuel Pump Will Not Work

The fuel pump is the device that delivers fuel to the engine. Most modern cars it is run by electricity. If it doesn’t receive any electricity from the supply source (which is the alternator), it can’t do its work, and the engine will not be able to run.

2. Power Steering Won’t Work

Most modern cars have power steering, in which the power is supplied by electricity. They are called electric power steering, as opposed to the older hydraulic power steering, which is fluid-driven.

Steering the wheels is made lighter and easier with the modern electric power steering. You don’t have to spend too much effort turning the wheels to the left or right. With power steering, you can even turn the wheels with just one finger.

However, when the electric power steering loses power, there is no way you can move your wheels, even if you’re a big muscleman. That’s dangerous if you are on the road. You won’t be able to steer your wheels to safety.

3. Electric Water Pump Will Not Work

The water pump distributes water from the radiator to the cooling channels of the engine, so your engine can run at its optimal working temperature. If this water pump does not receive any electricity, it won’t work and won’t be able to cool down the engine.

That’s dangerous because the engine can overheat. If it overheats, the pistons inside the cylinders could seize up. When that happens, your engine will stop. What happens afterward is a very pricey engine repair job.

4. All Car Lights Will Not Work

Your safety on the road is very dependent on your car lights. The headlights, signal lights, brake lights, and hazard lights are the only ways you can communicate with other drivers while on the road.

They won’t work if your alternator has gone bad. So, how can you ensure your safety if your car lights are not working?

How Far Can You Drive with a Bad Alternator

can u jump start a car with a bad alternator

There’s no clear-cut answer to this question because the answer depends on several things:

  • The current condition of the alternator
  • The current state of the battery
  • The age of the car
  • The current speed of the car
  • The amount of electrical load such as headlights, air conditioning, and so forth

But a rough estimate will be 13 to 15 miles or about 20 minutes of driving if you are after a number. You can extend this distance if you keep your engine RPM on the low side.

But if you have jumpstarted the engine, you would be lucky if you could travel longer than 7 to 10 miles or about 10 minutes.

Again, can you jumpstart a car with a bad alternator? You can jumpstart a car with a bad alternator if you have a good battery. And the car will continue running with the battery as the only voltage source.

Signs of a Bad Alternator

It’s stressful to be faced with an alternator that is not working suddenly. There are so many risks involved in this situation. So, how can you tell if the alternator in your car is already going bad so you can avoid this unexpected experience?

You need to be aware of some signs of a malfunctioning alternator:

1. Dim Interior Lights

If you notice that your cabin lights are no longer as bright as before, have a mechanic examine the condition of your alternator. For instance, if the lights on your dashboard gradually dimmed, your alternator might no longer be functioning 100 percent.

2. Strange Noise

When you started the engine, did you hear a strange noise coming from the engine bay? That noise can occur before the alternator completely fails.

3. Overly Bright or Dimming Headlights

Suppose you notice that your headlights are getting brighter as you accelerate and dimmer as you stop; these signs that the alternator is going bad. It could mean the alternator can’t keep the battery fully charged.

If you observe these three signs in your car, it’s time to take it to your trusted car mechanic. They are signs that your alternator is malfunctioning. Don’t wait until it completely fails because you don’t know what situation you will be in when that happens.

Average Lifespan of Alternators

How to Jumpstart a Car with a Bad Alternator

If you think you have a bad alternator and there’s nothing you can do but jumpstart the engine, here is the way. You can use the same procedure as jumpstarting a dead battery with slight differences.

If you need to drive your car to the car repair shop, you should at least give 15 minutes to charge the battery since it could drain very fast without the help of the alternator. Don’t skimp on the time if you don’t want to exacerbate your problems:

1. Preparation

  • You should have another car with a full working alternator and a fully charged battery. A friend’s car will be helpful for this purpose.
  • Ensure that the bodies of both cars are not touching each other.
  • Ensure that you know the positive (red) terminals and the negative (black) terminals of the two batteries.
  • Don’t let battery clamps touch each other.
  • Do not turn on any light or run any electrical device while your car is being jumpstarted.
  • Follow the steps below.

2. Attach Battery Clamps

  • Attach one end of the red clamp to the red terminal of the battery with the bad alternator.
  • Attach the other end of the red clamp to the other car’s battery.
  • Attach one end of the black clamp to the black terminal of the battery with the bad alternator.
  • Attach the other end of the black terminal to the ground. You can attach the clamp to any bare metal such as the bolt head, stud nut, or unpainted frame of the car.

3. Start the Engine

  • Start the engine of the car with a good battery and good alternator.
  • Run it for a minimum of 3 minutes at 2,000 RPM.
  • If you have to drive your car with a bad alternator, you must do this for at least 15 minutes at 2,000 RPM.
  • If your engine is cold, you may have to run jumpstart it longer than 15 minutes.
  • Once the time is reached, try to start your car.
  • If it doesn’t start still, give it another 3 minutes of jumpstarting.

4. Remove Clamps

  • If the engine with the bad alternator can crank and start, you are successful in jumpstarting it. Now, remove the clamps in an orderly manner.
  • Remove the black clamp attached to your formerly dead battery.
  • Remove the red clamp attached to your previously dead battery.
  • Remove the red clamp from the good battery.
  • Remove the black clamp from the good battery.

5. Fix Your Alternator

Now that you have a fully charged battery, you can run your car with it but only for a short distance. You must bring your car to your trusted mechanic and have the alternator fixed or replaced. Don’t drive your car on long trips until you have fixed this issue.

Frequently Asked Questions

will a car with a bad alternator start with a jump

You may still have some questions about this topic that you want to be answered. Here are the answers to the most often asked questions about this topic. The answer to your question may be one of them:

Can I Jumpstart My Car If the Alternator Is Already Bad?

Yes, you definitely can. No matter how bad your alternator is, there is a way you can jumpstart your car. But be aware that you can only travel so far, maybe around 10 miles, when the engine starts.

You see, when the alternator is not working, all the electrical needs of your car are supplied by the battery. So your battery must be fully charged to do this.

Even then, it can only go so far, and its juices will be completely spent since there is no alternator helping it to carry the electrical load.

How Can I Tell If the Alternator Is Bad and Not the Battery?

If you can start your engine, your battery is working fine. However, if the engine starts and dies soon after, your alternator is not working. You see, the battery’s primary purpose is to crank your engine.

Once your engine cranks, the alternator takes over the part of supplying the power to the electrical devices of your car. In other words, the battery is no longer required to supply electricity to the car. It is now the responsibility of the alternator.

Aside from being the power source for the car’s electrical devices, the alternator also charges the battery while the car runs. This is the importance of the alternator.

Without it, the battery will be forced to shoulder all the electrical chores. If its juices are all spent up, your car will die if the alternator isn’t doing its job.

What Are the Signs of a Failing Alternator?

There are several signs of a malfunctioning alternator. They include:

  • Overly bright headlights when accelerating and dimming headlights when the car stops.
  • Dimming cabin lights
  • Strange noise when you start the engine

In Closing: Is It Possible to Jumpstart a Car With a Bad Alternator?

You can jumpstart your car even if the alternator has already failed. If your battery is still working, it will be able to start and run your engine. In that case, you will be running your car purely from the battery’s power.

However, it will not be long before the engine stops again. The battery will be discharged pretty soon because it provides your car’s power to run. And since the alternator is not working, it won’t be able to charge the battery. That’s how vital an alternator is in your car.