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HomeWhatCar Alternator Light: What It Indicates And Possible Solutions

Car Alternator Light: What It Indicates And Possible Solutions

About Car Alternator Light, your car’s dashboard has many indicator lights and symbols.

Each has importance in the car and indicates a specific component’s correct functioning or malfunction.

However, one of the most important ones is the car alternator light.

When the red car alternator LED light flashes, it often spells trouble for drivers. At that point, you are unsure of what to do next.

But, not to worry, we have covered everything about car alternator lights flashing on and what it means.

We have also revealed the steps to take when your car alternator encounters a fault. 

Table of Contents

What is the alternator light?

This light indicates whether or not the car battery is charging.

While driving, the alternator light does not indicate unless there is a fault.

In that case, the car uses the battery energy without charging. Hence, it leads to complete drainage of the battery.

Connection Between Alternator And Battery

The battery and alternator are very crucial parts of an automobile running. The battery first powers up the vehicle giving it that initial energy.

On the other hand, the alternator or generator is responsible for keeping the battery running by generating the required voltage. 

Therefore, to operate a vehicle’s engine, there must be a link between the alternator and the battery.

The battery needs the alternator to charge, and the alternator needs the battery to start up in the first place.

A new car alternator

(A new car alternator)

Possible Reasons Your Battery Indicator Is On, But There is No Charge from the Alternator

  • An Explanation of the Alternator Warning Lights
  • Some reasons exist for keeping your battery indicator while not receiving a charge from the alternator. 

1. Alternator

A broken or damaged alternator belt is the most common cause of an alternator fault. Often, old age and weather conditions are the primary reasons.

As a result, the alternator belt becomes less flexible, dry, and worn out.

The battery indicators begin to flicker when these cracks develop from the stress and tension of usage.

In other cases, the problem extends to the ignition and headlight systems.

The wear and tear eventually cause the alternator belt to slack from the pulley.

You will detect this symptom by a high squealing sound from the engine.

In extreme cases, the alternator belt breaks. At this point, the car ignition system fails as well.

The engine may develop a severe fault if the car is in motion.

damaged alternator belt

(damaged alternator belt)

2. Battery

The battery issues primarily associated with the abovementioned fault include;

Dirty Battery Terminals

When the battery terminals collect dirt or other forms of debris, such as carbon, it restricts the flow of charges.

In such a case, the battery does not receive sufficient power from the alternator leading to a low voltage indication. 

Poor connection

Among the numerous cables that make up the recharging system of an automobile, there is the possibility of a loose connection somewhere.

Sometimes, it results from wearing and tearing, affecting the current passage between the alternator and battery. 

Battery terminal corrosion

It is normal for the terminals of a battery to rust over time. Corrosion is also a result of overcharging and excess heat. 

In any case, the battery temperature may rise and cause its electrolyte content to bubble and spill out.

This greenish-white electrolyte residue then deposits on the battery terminals, causing insulation.

As a result, the battery light on the car dashboard begins to blink.

Loose Battery Clamps

By default, these battery clamps hold the cables tightly to the battery terminals and ensure consistent transfer of electric charges.

However, the electrical conductivity fluctuates whenever the clamps at the battery terminals are loose.

Dead Battery

Finally, if the car battery is dead, it will indicate a red light on the vehicle dashboard.

These batteries last between four and six years on average. Mode of usage and maintenance further determine how much longer they last.

In most cases, the battery charge levels drop after the first year. The battery light, at this point, begins to display periodically.

The car then gets difficult to start. When ignored for too long, the charge levels drop to zero, becoming a dead or expired battery. 

A car battery with red and black cables

(A car battery with red and black cables).

3. Faulty Voltage Regulator

When the voltage regulator built-in for the recharging system goes bad, it affects the whole system.

The alternator misplaces the requirements of the battery by delivering excess charge to it.

Therefore, it leads to battery damage in the cases of corrosion and overcharging.

Automobile voltage regulator

(Automobile voltage regulator)

Actions to take if the battery light indicates

  1. The first point of action to take in such situations is to turn off all electrical systems. These include the car audio player, heater, AC, phone chargers, etc. Otherwise, turn off the ignition immediately if it affects the power steering or causes overheating. Afterward, take the following steps:
  2. Look carefully at the battery for corrosion or dirt. Ensure that the terminals are clean and that the clamps are tightly placed. 
  3. Inspect the alternator for missing electrical components and ensure the connections are intact.
  4. Also, the alternator belt should be in perfect condition. Check for cracks or loose ends if you experience overheating or losing power steering. 
  5. Examine the fuses even though they are not directly responsible for battery charging faults. However, any blown fuses always need replacing. 
  6. Ensure the battery is back in working condition by restarting your car engine. The light indicator will go off at this time if you have solved the issue. But, If the problem persists, your alternator is faulty. 
A healthy battery

(A healthy battery).

How much does an alternator replacement cost?

Alternator replacements range between 100 dollars and 400 dollars on average.

However, it depends on whether any other alternator parts need replacing.

If the serpentine belt wears out and needs replacing, an additional 30 to 50 dollars settles it.

Frequently Asked Questions

  1. Does the battery light indicate if there is an excess charge from the alternator?

Yes. In the case of overcharging from the alternator, the battery light turns on.

A simple test with a multimeter helps rectify this problem, though.

  1. Does a bad alternator turn the Battery Light?

Also yes. The battery light will come on when the alternator is bad. However, the issue is mainly from the voltage regulator or the battery whenever the red light comes on. 

  1. Does a flashing alternator light mean you can still drive your car? 

Yes. A flashing alternator light indicates that your battery is no longer charging even though little power is left to drive for a short distance. 

  1. What are the signs of a bad alternator on a car?

Some signs to look out for are difficulty starting the engine, stereo output problems, and faint lights.

Also, a prominent sign of a bad alternator is when your car halts while you are in motion.

  1. What is the lifespan of an alternator?

On average, alternators last up to seven years and serve from 80,000 to 150,000 miles.

Testing a battery with a multimeter

(Testing a battery with a multimeter)


The alternator and battery must function together for the car to operate well.

Therefore, a red light indicates on the car dashboard when there is a fault with the alternator or battery.

Observing any loose electrical connections or missing internal parts in your vehicle is proper. Read our other blog posts here for additional tips on maintaining your car. 

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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