Why Can’t an Alternator Charge an Electric Car?


Since the primary concern when owning an electric car is how to charge it, you might be wondering if an alternator can do the trick for you. After all, alternators have a tremendous amount of charging power in traditional gasoline powered vehicles. The question becomes if they can do the same thing in an electric car. 

An alternator cannot charge an electric car because the power source in such a vehicle is already generated from electricity. As such, it would not make any sense to first convert it one way, only to then revert to electricity. This would result in a net loss in terms of energy, which defeats the purpose. 

As technology continues to evolve, it is more important than ever to look for alternative ways to charge an electric car. If an alternator could do it, then car manufacturers would already be looking for ways of using this to their advantage. As it is, that simply cannot happen. Please continue reading to learn why that is and what it means to the electric vehicle industry. 

Why is an Alternator Not Necessary in an Electric Car?

You can think of an alternator as a type of generator. Its reason for being in a car is to use the electricity that is generated while it is running to charge the battery. Every vehicle that has a combustible engine will have an alternator. This component is usually located near the engine. You will recognize it because it has a belt running around it. 

In a regular vehicle, the alternator is meant to provide the car with most of the electricity that it needs to keep running. It also recharges the battery as you drive, which is why you can continue to start the car time after time. To accomplish this objective, the alternator has to take mechanical energy and turn it into electricity. 

When it comes to an electric car, this renders an alternator useless. To continue the discussion, it is helpful to know how an alternator ends up producing electricity in the first place. 

This is How an Alternator Generates Electricity

It all starts with the engine. Again, this is something that an electric vehicle does not have. Most vehicles produced today will have an alternator that becomes activated when the crankshaft from the engine is put into action as you start the car. The belt will start to move. This causes the rotor attached to the alternator to spin rapidly. 

As that rotor spins, electricity is created. Some magnets are strategically placed around the rotor. These create a magnetic field as they pass directly over some of the copper wiring that is there in the stator. 

Continuing the process, the magnetic field ends up producing a good amount of voltage that is then captured by the stator. Once that energy reaches a voltage regulator, it can then be sent back to the vehicle as electricity that the battery can then use to charge itself. Again, this works great in a gas powered vehicle, but not in one that is already powered by electric. 

Alternators Cannot Charge Electric Car

The easy answer to the question of why an alternator cannot charge an electric car is because such vehicles do not have one in the first place. However, there is more to the story than that. We must understand why electric vehicles do not use an alternator. 

The reason that an alternator exists is to keep the battery charged in a vehicle. We are talking about a 12-volt battery. As we have discussed, that purpose works well in a traditional vehicle, but not in one that runs on all electricity. In such a car, the 12-volt battery is separately charged via a DC-DC converter. 

What is a DC-DC Converter?

These types of converters are not unique to electric vehicles. They are found in many different types of technological gadgets that we use every day. As its name implies, the converter takes the DC voltage from one area and simply converts it to another. It does this continually. 

A DC-DC converter can be used for virtually any type of voltage combination that you can throw at it. It also works with various types of power sources. For it to work in electric cars, it is used to convert energy from the battery back, which is usually rated at 400 volts. This is then converted to the amount of voltage that is needed for a 12-volt battery. 

The function of the DC-DC converter is enough to charge a 12-volt battery rather easily. It is much easier to implement than an alternator, and manufacturers have found it to be much more reliable as well. This is why you will not find an alternator in an electric car. The DC-DC converter is a much better alternative. 

A Lesson in Physics

For an alternator to charge an all electric car, it would need to be attached to the wheels. Remember that an alternator is traditionally attached to the engine in a gas-powered, but no such options exist in an electric vehicle. 

For the energy from the wheels to provide the alternator with the power it needs to charge the battery, perpetual motion would have to be generated. Such machines are impossible. They do not exist. So, this idea is a non-starter. There is simply no way to use an alternator effectively in an all-electric car to charge the battery.

Is it Possible for an Alternator to Power a Hybrid Car?

Many people still wonder if it would be possible to use an alternator to provide a certain amount of power to an all-electric car. Simple physics make this a virtually impossible feat. However, alternators can be used in a hybrid car. 

In a hybrid vehicle, there is a small battery pack built into the design of the car. This contains just enough electricity to give the car the power it needs to drive a few miles. An example of this is what happens at a stoplight. The combustible engine shuts down. When the accelerator is pressed, electricity drives the car for a short distance before the engine turns back on. 

This is meant to increase the fuel efficiency of the car. This is also why many people ask why the same principle does not apply to an all-electric car. The reason is that there is no engine attached to switch back over to once the minimal amount of electricity charged while stopped at the light is used up. 

Even a plug-in hybrid vehicle can make use of an alternator is certain situations. It contains a larger battery back that will allow the vehicle to travel between 20 and 80 miles purely on electricity before having to switch back to gasoline. This battery pack can be charged two different ways:

  • From the traditional electrical grid
  • From a combustible gas engine

It is this second way that makes use of an alternator. So, again the question becomes why an alternator cannot provide a sufficient charge to the battery in order to eliminate the need to charge it at home altogether. 

Wrap-Up 

While alternators have proven to be one of the most useful parts of a gas-powered engine, they have no practical use in an electric vehicle. The best way to provide the necessary charge to an electric car remains to plug it in. Who knows what the future holds in terms of charging the battery, but for now, an alternator remains out of the picture. 

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