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Last Updated on January 21, 2022
It’s confusing to understand the difference between alternator and generator. They’re both used to generate electricity, but the way they do it is what makes them different.
When most people talk about a generator, their mind roams towards a portable generator you would use as a home backup or for a recreational vehicle.
Then, when we think about an alternator, we think of the device used to provide power to our car battery.
Those comparisons are accurate, but it’s essential to understand the technical differences of how these devices generate electricity and provide power to our homes and vehicles.
The simplified difference is an alternator is a device that converts mechanical energy into alternating current (AC) electrical energy. A generator is a mechanical device that converts mechanical energy into either alternating current (AC) or direct current (DC) electrical energy. Alternators produce more power than generators.
In this article, we’re here to teach you everything you need to know about the difference between Alternator and Generator.
What is an Alternator?
First, what is an alternator? It’s a type of generator that turns mechanical energy into electrical energy as an alternating current or AC.
These are common in the auto industry because they convert the mechanical energy under the hood into electricity that then charges your battery.
This mechanical process rotates a magnet, and that turning creates a current to distribute energy without converting it to Direct Current.
Alternators are efficient because they only provide energy when it’s needed. The alternator can come on and off as the battery needs to recharge. Because of this, your car doesn’t die when it’s running for a long time.
One way to tell if an alternator is bad is if your car battery dies when it’s still running. This issue would mean that the alternator is not providing a charge to the battery.
Overall, alternators are an enhanced version of a generator that can minimize the amount of power required, so there is less wasted energy.
The main thing to know about an alternator is that it cannot charge a completely drained battery. This can cause fires and further damage.
What is a Generator?
On the other side of the fence, we have a generator. This device converts mechanical energy into electrical energy as well.
The process is somewhat the same as the alternator, but a generator can provide an alternating current or a direct current (AC or DC).
Inside the generator, there is a rotor made of coiled wires. The rotating of these wires causes electricity to build up while the magnetic field housing it stays stationary.
When you have the rotation of the coils with the stationary magnet, it creates a magnetic field, which creates the amount of energy needed to spin the armature.
Hence, the magnetic field of an alternator is always rotating inside the stator, whereas, the magnetic field for a generator is fixed.
- Also read: 7 Best Quiet Generators In 2022
The armature is the rotating coil or series of coils in an electric motor. When the armature is stationary it becomes easy to produce voltage(low voltage) excitation to the rotor through the slip rings.
You would choose a generator when more electricity is needed because they produce voltage throughout the entire device without stopping. You can use a generator to charge a battery when it’s completely drained as well.
For this reason, we see generators as the best possible option as a power backup for homes and RVs.
These are cut out for the big jobs because the output current is constant, and it generates both Alternating current and Direct Current.
Understanding AC vs. DC
If you don’t understand the difference between AC and DC, it’s simple.
Your battery comes with a positive and negative terminal. Charged electrons move through the conductor, and they go from one terminal to the other.
As this happens, alternating currents reverse the flow of electrons, which creates an electron pulse.
This process creates energy currents that do not supply a constant stream of energy, which is more useful for conserving power.
Direct currents offer a constant flow of electrons in one single direction. When a specific frequency is required, alternating currents require more regulating devices to control the amount of energy generated to the source.
Alternator vs. Generator: The Differences
We’ve talked about it a bit, but let’s take a more in-depth look into what is the difference between an alternator vs generator.
- The alternator converts mechanical energy into electrical energy into AC electrical energy, while a generator converts it into both AC and DC.
- Alternators have a rotating magnetic field, and a generator has a stationary magnetic field which is fixed where the armature winding spins.
- Alternators receive input supply from the stator, and generators receive that input supply from the rotor.
- Alternators have RPM (rotations per minute) ranges, and a generator offers a slight variation in the RPM range.
- Alternators cannot charge a completely dead battery, whereas generators can charge a dead battery.
- Alternators have a higher output current than generators.
- An alternator is much smaller in size than a generator. (depending on the size of your generator)
- An alternator is to used to produce small-scale electricity or used as a charging system for automobiles, and generators are used to produce large-scale electricity.
- The brush efficiency of an alternator can last longer, whereas generators use brushes that do not last long when compared to an alternator.
Features to Look For in a Generator
If you’re looking for a portable generator to have for emergencies or recreation, there are many options out there, so you’ll want to choose carefully.
It’s challenging to understand the pros and cons of a generator if you don’t understand what they are.
In this section, let’s cover some of the things you’ll want to look for when you’re shopping for a portable generator.
1. Quick start
Newer generators come with a push-button start as opposed to the traditional pull-start that we all know and love.
We would always recommend choosing a portable generator with wheels. You never know where life will take you, and having to carry the generator requires a lot more effort.
3. Low-oil shutoff
The best generator will shut off when the oil falls below a specific level to protect you and the generator. Make sure your choice has this feature.
4. Plenty of outlets
You’ll want to spread the power out across many outlets instead of piling everything into one plug. It helps preserve the life of the generator, and it’s the safest way to get the power you need.
5. Alternate fuel
It’s nice to have options, and some portable generators provide propane or natural gas as their fuel source. Depending on your needs, you might even be able to convert the generator using a kit.
By now, you should understand the difference between these two. Both generators and alternators create power in the form of electricity.
The way both generators and alternators do it is a bit different, and they each have their pros and cons. Thanks for reading!
What are U trying to say . . . alternator/generator “receives” energy from (itself)?
Michael Sanders says
Hi Stef, I didn’t understand your question. Can you point to which statement in the article you’re referring? The article states that mechanical energy in both cases provides the means for both an alternator and a standard generator to provide electrical charge to downstream devices. In the case of an automobile alternator, it’s typically a belt that runs as part of the overall engine (which is powered by fuel). In the case of a standard generator, its fuel source directly runs the mechanism that generates electricity within the device and makes it available for downstream devices. I hope that clarifies. If not, please elaborate further and I’m happy to edit the article accordingly.
THOMAS CHRISTIAN says
I think the statement he’s referring to is this:
“When you have the rotation of the coils with the stationary magnet, it creates a magnetic field, which creates the energy needed to spin the armature.”
I thought the same thing as Stef.
Michael Sanders says
Thanks for the feedback, Thomas. How would you phrase it better so it’s more understandable or accurate?