You may think your car battery is powering all things electrical in your car, be it your windshield wipers, headlights or radio. In reality, it’s the car alternator that produces the majority of your vehicle’s electricity — your battery is mainly just used to start your vehicle and provide power when the engine isn’t running.
The alternator is a critical component of a car’s charging system, so it’s helpful to understand how it operates in case you have to deal with your car not starting.
What is an alternator?
An alternator is a type of electric generator used in modern car to charge the battery and to power the electrical system when its engine is running.
A car alternator, along with the battery and voltage regulator, is one of three main parts of a vehicle’s electric charging system. What an alternator does is supply electricity to be stored in a vehicle’s battery.
The alternator works by turning mechanical energy into electrical energy. When your engine is on, it powers a drive belt that rests on a pulley attached to the alternator. The pulley turns the alternator’s rotor shaft, which spins a set of magnets inside a coil.
These spinning magnets generate alternating current (AC) in the stator, which is then channelled to the alternator’s rectifier. The rectifier converts that AC energy into DC energy, which activates your car’s electrical systems.
What Does An Alternator Do?
An alternator, as an integral part of every combustion engine vehicle, its main responsibility is to convert chemical energy to electrical energy so that you can charge and replenish the battery in your engine and other electrical components in a car.
As the engine provides only mechanical energy, it does not generate electricity. So we need a power source which produces electricity to power all the electrical accessories in your car. And that’s where the alternator comes in. The vehicle’s charging system consists of a car battery, voltage regulator, and alternator.
Your alternator converts mechanical energy to electrical energy with an alternating current. The stator and rotor inside the alternator work as magnets and rotate to generate the alternating current. Then the alternating current(AC) is transformed into a direct current(DC) that charges the battery.
Both overcharging and undercharging your battery can be a serious issue. The voltage regulator sends the power from the alternator to the battery, controls the amount of energy to provide a steady flow of power to the battery.
Alternator Parts
As you can imagine there are differences in alternator construction and therefore there are different numbers of components depending on the supplier.
Alternators consist of three main components: rotor, stator, and rectifier. There are more components and we will come back to them throughout our discussion.
- Regulator. The voltage regulator controls the amount of power distributed from the alternator to the battery in order to control the charging process. Regulators are designed with different functions and work depending on their specifications.
- Rectifier. The rectifier is used to convert current from alternating current (AC) to direct current (DC) during the charging process.
- Rotor. The rotor is the spinning mass inside the alternator that rotates via the pulley and drive belt system. The rotor acts as a spinning electromagnet.
- Slip Rings. The Slip rings are used as a means of providing direct current and power to the rotor.
- Slip Ring End Bearing. The bearings are designed to support the rotation of the rotor shaft.
- Stator. The stator consists of several coils of wire wound through an iron ring. The stator sits outside the rotor, when a magnetic field is created the electrical current is made.
- Drive End Bearing. The bearings are designed to support the rotation of the rotor shaft.
- Pulley. The pulley is connected to the rotor shaft and the drive belt system. Rotation created by the engine the drive belt system turns the pulley beginning the charging process.
How does an alternator work?
As we know, the alternator provides your car with the bulk of its electricity and helps to recharge the battery. But to do all of that, the alternator must first turn mechanical energy into electricity.
How does The Alternator Produce Electricity?
The process of generating electricity begins with the engine. On most modern vehicles, alternators are driven from the engine’s crankshaft via a serpentine belt, although older vehicles may have a separate pulley leading from the crankshaft to the alternator.
The movement of the belt – the mechanical energy – spins the alternator rotor at high speed in the stator.
Electricity is generated when the rotor turns. The magnets surrounding the rotor are intentionally placed so that when they pass the copper wires in the stator, a magnetic field is created.
This magnetic field, in turn, produces a voltage that is captured by the stator. This power then reaches the voltage regulator, which distributes power to the vehicle and manages the amount of voltage the battery receives.
How Does The Alternator Charge The Battery?
Before the battery can use the energy coming from the alternator, it must be converted into a format that the battery can use. That’s because electricity can flow in different currents or directions.
Car batteries operate on one-way direct current (DC), while alternators produce alternating current (AC), which occasionally flows in reverse.
Before the current for the battery goes to the voltage regulator, it goes through a diode rectifier to convert it to DC. After the conversion, the battery can use the electricity for recharge. You can’t recharge your battery with a faulty alternator, look at these 7 warning signs of a bad alternator.
Warning Signs Of A Bad Alternator
Without a working alternator, your car won’t start in the near future or stay on for more than a few minutes. Yet the typical signs of a bad alternator are often mistaken for problems with the battery or other car parts that display similar symptoms. In other words, if you’re experiencing only one of the issues below, it may be a sign of a bad alternator:
- Dim or overly bright lights
- Your battery is dead
- Slow or malfunctioning accessories
- Trouble starting or frequent stalling
- Growling or whining noises
- Smelling burning rubber or wires
- Lit up battery warning light on dash
While these can be helpful indicators, any of these warning signs can also point to potential issues overall with your vehicle’s electrical system.
How Long Does An Alternator Last?
You may also be wondering about the alternator lifespan. The average lifespan for most alternators ranges from 80,000 and 150,000 miles. Usually, an alternator lasts about seven years. There are a few factors that can affect your alternator lifespan on the roads of Blasdell.
- Alternator quality
- Driving conditions
- Power drain on the alternator
How much does it cost to replace an alternator? Different alternators are required for different vehicles. So, the price depends on the make/year and model. But before replacing your alternator, you need to check if it is working or not. If you don’t know how to do this, read our guide How to test an alternator?