Alternator vs Generator: What Is The Difference?

You probably already know that motor vehicles use alternators to charge their batteries. You also know that people use generators as power backup systems in residential and commercial properties.

However, you could be wondering, what’s the difference between these devices as they both generate electricity.

An alternator is actually a type of generator. While these devices serve the same purpose, they are different in terms of operation. An alternator converts mechanical energy into AC (alternating current) electrical energy.

A generator, on the other hand, converts mechanical energy into either DC (direct current) or AC electrical energy. If you supply them with electrical energy instead of mechanical energy, both devices can work as electric motors.

 

Alternators use only the required amount of energy, so they conserve more energy. Conversely, generators use all the energy produced, so they conserve less energy. What’s more, alternators are usually smaller in size than generators.

Keep on reading to learn more about alternators vs generators.

 

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What Is An Alternator?

An alternator is a device that generates electric power in a vehicle. It’s an integral component of the vehicle’s charging system.

Every car with an internal combustion engine, except for some hybrid vehicles, has an alternator. When the engine is running, the alternator not only charges the battery but also supplies electric power to the vehicle’s electrical components.

The engine drives the alternator using a serpentine belt. Alternators are maintenance-free and can last for at least 10 years without any repairs. If this device malfunctions, your car may still run for a short while on battery power.

The engine will shut down once you deplete the battery power. Also worthy of note is that an alternator cannot charge a dead battery.

How Does It Work?

An alternator consists of a stationary armature, inside which a rotor revolves. Mounted on the rotor is an electromagnetic field system.

A small amount of DC power activates this electromagnetic field through copper or carbon brushes (contacts) that touch two rotating metal slip rings on a shaft. This results in a stronger magnetic field.

A prime mover helps to rotate the rotor, and the activation of the electromagnetic field produces a rotating magnetic field. The rotation, in turn, produces much more electricity.

This electricity is alternating current (AC), which can be collected and used to power other devices like the vehicle’s electrical components. Hydro, thermal, and nuclear power stations also use large alternators for bulk power generation.

 

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What Is A Generator

A generator is a device that can generate energy. It can convert any type of energy, such as chemical or mechanical, into electrical energy.

Besides producing backup power for commercial or domestic use during an outage, generators can also generate the electrical power required for trains, aircraft, and ships.

Electricity companies use large-scale power generators to produce electricity for transmission over power lines to residential and commercial customers.

Types of Generator

There are three major types of generators – standby, portable, and inverter. Let’s take a detailed look at each:

Portable Generators

As the name suggests, a portable generator isn’t designed for permanent installation. This is a diesel or gas-powered device that provides temporary electrical power.

Portable generators normally have a run time of up to 12 hours, with a power output of 500 watts to 17.5 kilowatts. Common uses of portable generators may include:

• Powering small domestic appliances like lights, TV, computer, and refrigerator
• Camping and garden use
• Building and construction sites
• Onboard electrical power for boats
• Prolonged power outages

Inverter Generators

An inverter generator utilizes an engine connected to an alternator to generate AC power. Unlike other generators, it also uses a rectifier to convert the AC power to DC power.

These generators are more energy-efficient since the engine speed adjusts automatically according to the amount of power you require. They also produce lower emissions, are more portable, and are generally very quiet.

 

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Standby Generators

Often referred to as a backup generator or emergency power system, a standby generator ensures your power doesn’t go off during an outage. It’s installed outside the building and switches itself on automatically.

A few seconds after an outage, the standby generator activates, supplying power to your outlets and light sockets. The major types of standby generators are diesel, gas, and bi-fuel standby generators.

You can also categorize generators based on the type of fuel they use, namely:

• Diesel generators
• Natural gas generators
• Gasoline generators
• Solar generators

 

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How Do They Work?

A generator consists of a rotor made of coiled wires, known as the armature. When these wires rotate, they cause electricity to build up while the magnetic field housing the armature remains stationary.

The rotation of the coils within the stationary magnet creates a magnetic field that produces the energy required to rotate the armature.

As the armature rotates, it cuts the magnetic field, which results in AC power. This power is harvested through the brush and slip ring. If you need DC power, a commutator will help you convert the AC power to DC power.

Alternator vs Generator: Summing Up

Both generators and alternators generate electric power, but they are different in several ways. The alternator produces AC power from mechanical energy while the generator can produce both DC and AC power.

While an alternator has a rotating magnetic field, a generator uses a stationary magnetic field. An alternator receives energy from the stator, while a generator gets its energy from the rotor.

You can’t charge a completely dead battery with an alternator, but you can do it with a generator. An alternator generally has a higher output than a generator. However, alternators are usually smaller in size compared to generators.

There are several types of generators, including standby generators, inverter generators, and portable generators. You can choose a generator based on your specific needs, whether commercial or domestic. Alternators are mainly used in vehicles, but they can also help in bulk power generation at power stations.