Difference Between Alternator And Generator

Difference between alternator and generator is given here which explains how they are different from each other with respect to structure, output, efficiency, etc. These alternator generator differences can help to clear any doubt regarding this topic. Here, the main alternator and generator differences in tabular form are given for easy understanding.

Difference Between Alternator And Generator

Before starting with the differences, it is important to know what a generator is and how does it work. In simple words, generators and alternators are both mechanical devices that convert mechanical energy to electrical energy. To learn more about them, visit the following articles.

Difference Between Alternator And Generator

Sl. No.

Differentiating Property





An alternator is a device that converts mechanical energy into AC electrical energy.

A generator is a mechanical device which converts mechanical energy to either AC or DC electrical energy.


Output Current

An alternator always induces an alternating current.

A generator can generate either alternating or direct current.


Energy Efficiency

Alternators are very efficient.

Generators are considered less efficient.



Alternators have higher output than generators.

Generators have a lower output when compared with an alternator.


Energy Conservation

Alternators use only the required amount of energy and thus, it conserves more energy.

Generators use all the energy that is produced and so, they conserve less energy.


Polarization After Installation

Polarization is not required in case of alternators.

Generators need to be polarized after installation.


Magnetic Field

The magnetic field is rotating inside the stator of an alternator.

In case of a generator, the magnetic field is stationary or fixed where the armature winding spins.


Armature Movement

The armature of an alternator is stationary.

The armature of a generator is rotating.


Input Supply

The alternator takes input supply from the stator.

The generator takes input supply from the rotor.


RPM (Rotation Per Minute) Range

Alternators have a wide range of RPM.

Generators have a low range of RPM.


Voltage Generation

Alternators produce voltage only when needed.

Generators produce voltage at all times.



Alternators are generally smaller in size.

Generators are larger and require more space to fit in.


Brush Efficiency

The brushes of alternators last longer.

The brushes of generators last lesser when compared to an alternator.


Charging of a Dead Battery

Alternators will never charge a dead battery

A generator can be used for charging a dead battery.



Alternators are mainly used in the automobile industry as a charging system for the battery.

Generators are widely used to produce large-scale electricity.

These were the main differences between alternators and generators. These alternators and generator differences are a bit in-depth to help the students get a complete idea about them. These detailed and advanced comparisons can help the students to get completely thorough with these respective topics.

This comparison can also help the engineering aspirants to get acquainted with these concepts. To get more such detailed comparisons and differences, keep visiting BYJU’S.

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