Can An Alternator Be Used As Generator(What’s the difference)?

It is not easy to comprehend the difference between alternators and generators. Both of these follow the working principle of the Faraday law of electromagnetic induction. Both generate electricity and have a significant market demand.

Can an alternator be used as a generator? Yes, you can use an alternator as a generator in the following ways:

  • Initially, you need to run an alternator with a motor. It maintains charge in the battery
  • Use inverter to provide AC current
  • Use charge controller to stop the motor when the battery gets fully charged. You will need to use a voltage-sensitive relay.
  • Optimize the cost by running the motor at low speed with a wide-open throttle

You can check out this video to know more in detail!

When we think of a generator, what comes to our mind is an alternative domestic power supplier. And when we talk about an alternator, the first thing that comes to mind is a device charging an automobile battery. While these differences are true, it is crucial to understand Alternator, Generator, A.C, D.C, and the working principle.

What Is an Alternator?

An alternator is a type of generator that converts mechanical energy into electrical energy and produces alternating current (AC).

It is commonly used in automobiles to provide enough charge to the battery to keep your car running.

An alternator is an efficient device that consumes and wastes less energy.

What Is a Generator?

A generator also converts mechanical energy into electrical energy, but the output is direct current (DC) or alternating current (AC). Thus, the process is almost similar, but it produces electricity in the form of AC as well as DC.

However, initially, generators produce an alternating current, which is converted to direct current through a commutator.

A generator is commonly used as an alternative power supply when you need more voltage. It works without stopping, and so offers constant power output.

Difference Between AC and DC

Before we move to the differences between alternators and generators, it is important to clarify the difference between alternating current (AC) and direct current (DC). It will help understand the working mechanism of both.

It’s quite easy to understand how AC and DC work. Every battery comes with a positive and negative terminal. Charged electrons move from one terminal to the other.

Alternating current reverses the process, and so, electrons move in both directions (from negative to positive and positive to negative). This does not allow constant energy stream. Thus, it helps conserve power.

On the other hand, direct current allows a constant flow of electrons in one direction. Thus, it produces constant electricity. However, it takes more mechanical energy.

Differences Between Alternators and Generators

Now, even though the working principle is the same, there are some significant differences in the working and mechanisms of alternators and generators. Here is a detailed comparison to help you understand better:

Magnetic Field

An alternator features a rotating magnetic field while a generator has a fixed or static magnetic field. That’s why the alternator has a variable output EMF, and a generator has a constant output EMF.

Energy Supply

An alternator gathers energy supply from the stator, whereas a generator receives its energy supply from the rotor.


Alternators offer higher output compared to generators.

Energy Conservation

As an alternator produces electricity only when requires, it consumes lesser mechanical power and conserves more energy. On the other hand, a generator wastes more energy as it delivers a constant power supply.

Rotation per Minute (RPM) Range

Alternators have a wider RMP range, while generators have a lower RPM range.

Size and Weight

Alternators come in a smaller size and are lighter as they need to be fitted inside vehicles. Generators are bigger and heavier and require more space.

Charging a Dead Battery

You cannot use an alternator to charge a dead battery; however, generators can efficiently charge a dead battery.

Need for Polarization

Alternators do not require polarization after you install them. In the case of generators, they need to be polarized to function.

Advantages of an Alternator Over a Generator

While several advantages of alternators are clear from the above comparison, here is a detailed discussion of how alternators are a better option than generators.

Energy Efficiency

Alternators are highly energy-efficient not only in terms of consumption but output as well. They take in lesser energy and produce a higher output as compared to generators. Thus, they conserve energy while generating a high amount of power.

Effective Alternators Help Reduce Fleets

Brush Efficiency

The brushes of alternators are better than those of generators. They deliver better performance and last longer. Thus, you need not worry about high maintenance and repairs.

Higher Output

The parts of alternators are more active and efficient than a DC generator. This enables them to rotate quicker with a low risk of damage. This higher rotation speed means that an alternator can generate higher power in lesser time.

This also shows that an alternator can generate power even when running at a low speed. This lets the battery charge even when you are driving your car.

Compact and Lightweight

The best thing about alternators is its compact size and lightweight.

Alternators are significantly lighter than generators. The lesser the weight of your car, the higher the fuel economy. This means you need not spend a lot on fuel refills.

Secondly, the small size makes it easier to fit an alternator in the engine, which is already crowded with other parts and compartments. This also helps in easy maintenance and repair as there’s enough space to work in.

Lower Maintenance Needs

Both DC generators and alternators have almost the same build. You will find rings, brushes, and wires in each; however, the design is different.

While generators include split rings, alternators come with solid rings. Brushes run against these rings, respectively.

When it comes to wear and tear, brushes of a DC generator quickly wear as they constantly rub against split rings. On the other hand, alternator features smooth brushes, and so they do not wear off quickly. Thus, alternators require lesser maintenance.


While both alternators and generators can deliver the power output and energy supply you require, an alternator seems to be a more plausible option given its energy conservation, cost efficiency, and higher output. Also, it weighs less and takes up lesser space.

However, make sure you make the right decision depending on the environment and your energy requirements.


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