Can A Car Run With Bad Alternator? [Ultimate Guide]

 An Alternator plays a vital role in your vehicle and driving experience. A car is comprised of three major components: an alternator, a battery and a voltage regulator. 

The alternator functions along with the battery to generate power for the electrical parts of your car, like the instrumental panel, lights, and so on. Found typically near the front part of your engine, a car without a properly functioning electric motor is almost useless.

Which is why making sure that you have a good alternator is important. Heres how you can check, test and make sure your alternator is working perfectly, to ensure a smooth drive.

What Are The Symptoms of A Bad Alternator?

Some ways that you can determine whether or not your alternator is bad are:

  • Weak/Dead Battery: As the battery of your car plays an important role in the functioning in your car, a battery health goes hand in hand with your alternators. Which is why if your battery seems to be weak or had died, its highly likey that your alternator has gone bad as well. Although an alternator can recharge the battery in your car, it wont keep it going forever. This is why it is important for you to distinguish if you have a bad alternator or a weak/dead battery. I’ll guide you more about this later in the article.
  • Flicking Headlights: The flickering of your headlights is one of the first signs your car will show when its alternator is starting to go bad. If you see your headlights going dim, weakening or flickering, this is a clear indication that your alternator is going bad.
  • Difficulty Starting Your Car: If it takes you more than one try to start your car before finally starting up, it also may be due to a bad alternator. Although your cars warning light will turn on in case of a bad alternator but if you dont have that sign, the above points should help you check if your alternator is bad.

How To Check If Its Failing?

Okay so now youve got it down that your alternator has in fact gone bad. So how do you test if your alternator is in order or not? Here are some ways that you can test out it through a screwdriver, by a bench test or by simply disconnecting.


First off, put your car keys into the ignition switch but do not start the engine. Open your car hood to gain access to the test alternators current. After you’ve reached the alternator’s current, test its magnetism by putting the metal screwdriver near the bolt of the motors pully.

Now have someone turn the car (without starting it). With this you will be able to turn the voltage regulator, put the metal side of the screwdriver to the near the nut on the alternator pulley. Now you will be able to see a high magnetism which will attract the screwdriver.

In case this event takes place, your alternator is working perfectly. But if it didnt then it means it is indeed bad.

By Disconnecting:

Start off by putting your car into an open space like a driveway and open the hood. Turn your car on by starting it, if your alternator has indeed gone bad you may face some problems whilst starting it up.

During your car running, leave your drivers seat and under the hood, check for the battery of your car and disconnect it. Now you must check if the car is running like it was before or not, if it does then great! Its working just fine, but if not then your it may be bad.

Bench Test

Position your alternator into the clamps on the bench test equipment. Then proceed to connect the belt, test leads and then use its electric motor to spin the it.

The great thing about testing your alternator with a bench test is that you wont only test if the alternator is good or bad, but also test parts related to it. Like wires, tension, belt and more.

How Much Does It Cost?

The average price of a brand new electric motor is range up to $130-$250 dollars. With the lower end of the price offers a professionally remanufactured alternator and the higher end is for high-quality new alternators for modern cars.

Can You Still Drive It?

You must understand, as mentioned before, that an alternator plays a quite critical role in the functioning of your car. The alternator almost ties your entire car together, connecting to your vehicle as an electric generator. Its connected to your headlights, GPS, battery recharge, fuel injection and so on.

By the time you start to see the above-mentioned signs of flickering headlights, or weak/dying battery, its pretty evident that it has given up. And is already near the failure point of breaking down. So it would be important to replace it to avoid getting stranded as you wouldn’t have a lot of time left.

Driving with a failing alternator would be highly risky for your life, and your vehicle as well. With an alternator of this condition, your car wouldn’t last too long before dying. It would, give or take, get 50-100 miles before it finally wears down.

Jump-Starting A Car with Bad Alternator:

Now you’re stranded in the middle of nowhere and need to jump start your car, so how exactly do you do that? Here’s how:

  1. Make sure you have another car with a good battery to jump start your own car. And that your car is not running
  2. Connect the positive and negative wires to their respective terminals
  3. Start your engine with the good battery and run it for about 3-4 minutes. Give it more time if you feel like your current one is too bad.
  4. Once your car has started, remove the cables and seek your nearest mechanic for a new one and replace your bad one. It doesn’t take to

Bad Battery Vs Bad Alternator:

As your vehicles battery and alternator go hand in hand, its important to figure out which one is going bad.

So you are able to get to the root of the problem and fix it accordingly.

A bad battery would cause your engine to crack sluggishly. It would prove to be difficult to start during a cold morning, or there’s no sound or lights when you try to start your car. A poor battery would have visible corrosion on itself that shows it may be damaged.

If your jump start works, it would also mean that your battery is indeed the root of the problem here.

However, if you have a bad alternator your car wouldn’t be able to start at all or would have trouble starting. The headlights would be flickering, or dimming, interior lights would face difficulty to turn on, or stereo system wouldn’t be working.


With the following you now have gained the perfect knowledge of whether or not you would be able to run your car with a failing Alternator.

 So now that you have all the knowledge you need, what are you waiting for? Get your hands dirty and lets get those engines ready to roll! 

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