7 signs of bad or faulty alternator

Mechanical and electrical energy is used in today’s automobiles. Through combustion, your engine generates mechanical power, which is used to move your wheels. Meanwhile, your battery provides electrical power to a variety of other devices, including your headlights and radio.

The alternator, which turns mechanical energy into electrical energy and keeps the battery charged, connects the two systems. When an alternator fails to function properly, it can result in a range of issues. However, you’ll almost certainly notice one or more of these seven indicators of a damaged alternator before that happens.

symptoms of bad alternator

In this article, you’ll learn the common bad sign and symptoms of a faulty alternator. Some FAQs on the faulty alternator are explained. which includes:

  • How do I know if I have a bad alternator?
  • How much do alternator repairs cost?
  • Can a car run with a bad alternator?
  • How do I know if it’s the battery or alternator?
  • What sound does a bad alternator make?


Read more: Understanding alternator


Signs of a Bad Alternator

The followings are the common signs you experience when your car alternator is faulty or bad:

  • Dim Or Overly Bright Lights
  • Dead Battery
  • Electrical Issues
  • Engine Stalling
  • Growling Or Whining Noises
  • Smell Of Burning Rubber or Wires
  • Battery Warning Light on Dash

Dim Or Overly Bright Lights

It’s possible that your headlights will dim or brighten unevenly, or even flicker. This could indicate that the alternator in the car is having problems delivering constant power. Revving the engine is one technique to check. If your headlights shine at a greater RPM yet fade as you let go of the accelerator, your automobile alternator is most likely broken.

Dead Battery

A car that won’t start almost invariably has a dead battery. If you jump-start the automobile and it starts and runs normally, the issue is most likely with the battery. If you forget to turn off your lights, for example, the battery may have simply gone exhausted. In such circumstances, jump-starting the automobile and letting it run for a few minutes will solve the problem.

If your car starts after being jumped but won’t turn over the next time you attempt, you may need a new battery. You know the alternator is still capable of performing its function because the automobile continues to run after it is started. Instead, the battery does not appear to be capable of maintaining a charge when the engine is turned off.

If your engine dies again after jumping the battery for a few seconds or minutes, the problem is most likely with your alternator. In fact, your alternator could be completely dead. Installing a new battery may temporarily solve the problem. However, once the replacement battery’s power has been depleted, you’ll be stuck with a car that won’t start.


Read more: Understanding Car Dashboard Lights and Indicators


Smell Of Burning Rubber or Wires

A burning rubber or wire stench could signal that your alternator’s parts are beginning to wear out. Because the alternator’s drive belt is constantly under tension and friction, and because it is so close to the hot engine, it may wear out and emit an unpleasant burning rubber odor over time.

Likewise, if your alternator is overworked or has frayed or damaged wires, you may detect a burning stench similar to that of an electrical fire.

An overworked alternator tries to pump too much current down its wires, which causes them to overheat and become dangerously hot. Damaged wires also generate resistance to electricity flow, causing the wires to heat up and emit an unpleasant odor.

Battery Warning Light on Dash

When the battery warning light illuminates on the dashboard, it’s often misinterpreted as a problem with the battery. The battery warning light, on the other hand, warns that there may be a problem with your car’s larger electrical system, which includes the alternator.

Alternators are made to operate at a specified voltage, usually between 13 and 14.5 volts. The voltage of your alternator may drop below capacity if it fails, causing the battery warning light to illuminate on your dashboard. Similarly, depending on how much stress the alternator is under, the battery light will appear if it exceeds its voltage limit.

The battery warning light may flicker on and off depending on the electrical load from your car’s accessories (headlights, wipers, radio, etc.) when the alternator varies in and out of its intended voltage capacity. While this may seem like a little inconvenience, it’s preferable to get your car checked for an alternator than to be stranded on the side of the road.

If you experience any of these symptoms, you should get medical help as soon as possible. Even if your automobile keeps running, the alternator may eventually fail.

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Electrical Issues

A failing alternator can cause plenty of additional electrical problems. In general, such difficulties manifest as an inability to perform at full capacity. You might notice, for example, that your headlights are dimmer than usual, or that their brightness swings strangely.

Dash and dome lights that flicker or appear dim are other warning indications. It’s possible that automatic windows will open and close significantly more slowly than usual. Alternatively, your radio and/or entertainment centers may shut down on their own from time to time.


Read more: Understanding Engine Starter Motor


Engine Stalling

A car that won’t start nearly always has a dead alternator. However, before things get to that point, you can run across a slew of other issues. An alternator that is defective or failing may only work in fits and starts. As a result, even if your engine is running, the alternator may not be able to keep your battery fully charged.

As a result, your car may stall out at inconvenient moments. The fuel injectors, which require electricity to function, are frequently the immediate cause of stalling. The fuel injectors may not fire if your alternator fails to keep your battery constantly charged, causing your engine to stall.

Growling Or Whining Noises

Cars emit a variety of strange noises, some of which are harmless and others that can signify major mechanical issues. You may have alternator difficulties if you hear growling or whining noises coming from under the hood, which should be looked up by a professional as soon as possible.

When the belt that turns the alternator’s pulley becomes misaligned or rubs against the side of the pulley, it makes a growling or whining sound. This sound can also be heard if the bearings that rotate the rotor shaft are worn out.


How much do alternator repairs cost?

It depends on whether or not a repair is possible. If not, you’ll have to replace it, which can cost anywhere from $500 to $1,000. (Including parts and labor). Otherwise, expect to pay between $100 and $150 for something as basic as replacing an alternator belt (not including diagnosis).

Can a car run with a bad alternator?

With a failed alternator, a car can only run for a brief time. When the engine is running, the alternator charges the battery, and once the battery is empty, the car will die and not restart.

How do I know if it’s the battery or alternator?

If the engine starts but then dies, your alternator is most likely failing to keep your battery charged. If a jump-start keeps your car running but it won’t start again on its own power, the problem is most likely a dead battery.

What sound does a bad alternator make?

Extremely high-pitched whining noise is a common sound created by failed alternators when the engine is operating. As the RMPs grow, such as when you accelerate, the noise will become louder and more obnoxious as the pulley spins faster.


Read more: Understanding the working of Battery ignition system



A bad or faulty alternative is a serious issue a car owner can experience as it results in other problems. I hope this article has guided you on how to go about signs of bad alternators and some important questions are being answered.

I hope you learn a lot from the reading, if so, kindly share with other students. Thanks for reading, see you around!