Do Alternator Whine?

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Getting into my car to drive down the road to my favorite restaurant for my weekend ritual- sipping a cup of iced chamomile tea and typing away on my laptop.

On starting the engine, I hear this piercing squealing sound coming from the engine. I was quite taken aback and had to cancel my plans for that weekend instead, booking an appointment with the mechanic.

After the routine investigation, it was diagnosed that the squealing sound was in fact, due to a faulty alternator. I had to get it changed to avoid compounding problems.

Back to the question raised by this article, ‘Do alternators whine?’ the answer is Yes, they do. The sounds made by an alternator varies and can arise from a myriad of causes which we would be discussing as well as what an alternator is, its types, applications, and signs that indicate a faulty alternator.

Table Of Contents

What Causes An Alternator To Whine?

As we have understood that the alternator plays a very significant role in maintaining and powering the electrical system of the automobile, it is of no surprise that a faulty alternator could lead to a variety of inconveniences, the uncomfortable whining sound included.

It is necessary to properly investigate and identify the cause of the sound to properly solve the shortcomings and prevent further compounding problems.

Over time, constant wear and tear that comes with the usage of mechanical tools take its toll on the engine and alternator. The following are some faults that develop and can cause an alternator to make squeaking, whining sounds:

Worn out alternator belts: Due to the friction created as the belt passes through the pulley system, the belt becomes worn over time and possibly snap. As one tries to start the engine, more work is done by the alternator to create sufficient current needed to keep the car functioning properly. This is a downward progression that would ultimately produce the whining sound that is commonly heard.
Worn out alternator bearings: Alternator bearings refer to the components built on the rotor that allows the rotor to rotate thereby, producing electrical energy. Over time, due to friction generated with, excessive heat generation and accumulation of debris, the efficiency of the alternator bearings is decreased. This would ultimately reduce the voltage output and electrical charge produced.
Loosened bolts: While driving, the car experiences different movements and shaking, some of which can be very violent and rough. It is of no surprise that the alternator bolts holding the various parts of the alternator in place can come loose. This would result in the parts of the alternator knocking against other parts of the engine, creating a characteristic ‘knocking’ sound and decreased efficiency of the alternator.

Signs That Indicate A Faulty Alternator

Before a piece of equipment or an appliance packs up, there are telltale signs observed beforehand. The alternator is no exception. One needs to be observant and able to identify these signs to take the necessary actions required. Some of these signs include:

Difficulty in getting your car started: This is a common and important sign one should not ignore. Having to start your car a couple of times before the engine comes on is a clear indicator that the alternator should be changed. This is of course, after ruling out the possibility of a faulty battery.

One way to test if the fault is from the battery or the alternator is to kickstart your car, if it goes off immediately, then the issue is a faulty alternator as there is not enough voltage to power the car to keep it running. However, if your car stays on, then you should consider replacing the battery.

Uncharacteristic sounds: When trying to start your car and you notice unusual sounds such as a knocking or whining sound coming from the engine, kindly do not take this for granted as it is usually an indicator of a faulty alternator.
Malfunctioning of other parts of the car: Since the alternator is significantly responsible for maintaining the smooth running of the car, a fault is likely to manifest as abnormal behaviors of other parts such as the headlights appearing too dull or flickering when turned on.
Foul, burning smell: One of the telltale signs of a faulty alternator is the emission of an unpleasant burning smell- the smell of burnt rubber. This is commonly due to overheating of the alternator, excessive friction, or even the alternator belts getting burnt as a result of the excessive heat generated.

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What Does A Faulty Alternator Sound like?

As described above, when a car with a faulty alternator is powered, a variety of sounds can be produced depending on the aspect of the alternator at fault. These sounds include:

Whining sound: This is the most common sound produced when an alternator is faulty. As the car is accelerated, the sensors signal the alternator to produce extra electrical charge to make up for decreased voltage output.
Knocking sound: This is often described as a ‘thump sound’- caused by 2 or more objects coming in contact. It gets louder when the car is accelerated and usually as a result of a torn belt, loosened bolts, or alternator parts coming in contact with other parts of the engine.
Grinding sound: These scratchy sounds are produced by ‘hard, rough surfaces rubbing on each other’. It may result from wear on the rotor shaft of the pulley system.

what To Do If An Alternator Begins To Whine?

While it is said that a car with a faulty alternator may still function (albeit with a few hiccups), it is safer to get to the root of the problem and take the necessary actions. Depending on the severity and part of the alternator affected, the following corrective steps can be taken:

Check and secure the alternator (or serpentine) belt tightly around the pulley wheel.
Check the alternator bearings. Most of the time, it is advisable to replace them entirely.

Check and fasten the alternator bolts

Check and repair other fractured parts of the alternator such as the rotor, rectifier e.t.c.
In more severe cases, the entire alternator might be replaced completely.

In conclusion, an alternator is a crucial part of most engines responsible for the conversion of mechanical energy to electrical energy. In automobiles, it is estimated that the alternator can serve throughout the lifespan of the vehicle however, it is not always the case.

In the advent of unusual sounds from one’s engine or alternator such as whining, grinding, knocking e.t.c, it is very important to investigate and identify the cause as well as take the necessary action to avoid ultimately draining your car battery.

Frequently asked questions(FAQ)

What is an alternator?

An alternator is a crucial part of any combustion engine electrical system, be it a car, boat, radio e.t.c. The alternator is a piece of equipment in modern technology that is responsible for converting the mechanical engine into electrical energy- an alternating current which in turn, starts the engine of your car.

The alternator is attached to the engine via a belt and pulley system thus when the engine is ignited, the belts begin to spin on the rotor shafts.

This generates alternating currents which are then transmitted to the rectifier. The rectifier is responsible for the conversion of alternating current to the direct current that powers the car.

The alternator is often mistaken for the battery as its function is conditioned by the other, however, the battery and the alternator are different as the battery generates a large amount of energy to start the car while the alternator provides the subsequent energy to keep the car functioning as well as recharges the battery.

The alternator was invented in the early 19th century by Lord Kelvin and Sebastian Ferranti but they rose to popularity in the late 19th century.

Alternators are divided into different types based on the following criteria: their uses, mode of excitation, type of rotation, cooling method, and several phases. Some examples include:

Permanent magnet alternators.
Brushless alternators.
Single-phase generator
Polyphase coil.

What are the parts of an alternator?

The alternator is broadly divided into 2 compartments: the inner and outer compartments. These compartments contain the following:

Outer Compartment

Pulley wheel: this wheel has depressions engraved in it that help to hold the belt in place and allow the belt to provide the mechanical force required.
Pulley shaft: The pulley wheel is joined to the pulley shaft and this shaft spans the entire length of the alternator.

Inner Compartment

Stator: It does not rotate like the pulley wheel. Coiled around the stator are three sets of copper wires arranged in a particular pattern to produce three different phases of alternating current which are then transmitted to the rectifier.
Rotor: This is an inner cylindrical core of the alternator usually made of steel that is connected to the shaft. It has a coil of wire wound around it.
Brushes: These are a set of carbon blocks that protrude to touch the rotor, producing electricity. As the electricity passes through the coil of wire on the rotor, an electromagnetic field is produced. When the engine turns the shaft, it also rotates this rotor along with the coils of the stator and this is responsible for the phases of alternating current created by the stator.
Rectifier and diode: The rectifier is a semiconductor, commonly made from copper, iron e.t.c that converts the generated alternating current to the direct current used to power the car. The voltage output of the alternator differs from the speed of the car. Thus, the faster the car moves, the higher the voltage output and vice versa.
Regulator: This is an integrated circuit that is mounted at the end of the alternator that monitors the voltage output of the alternator.

Application Of Alternator

Alternators have been employed in various areas of modern technology to generate electric energy. Some of these include such as:

In automotive technology: In this aspect of technology, automotive alternators are employed and they are usually found within the engine chamber of the automobile. These alternators are used to charge the car battery and power automobiles throughout use. They work based on the principle of the belt-pulley system explained earlier in the article.

Marine alternators: These are used for powerboats, yachts and are similar to automotive alternators. They have been specially adapted the salt-water environments.

Radio alternators: Alternators have also been employed in the communication sector, particularly in radio frequency transmission.

Diesel-electric locomotive alternators