Why Can’t Electric Cars Charge Themselves While Driving?


If you think it would be wonderful for your electric vehicle to charge itself as you were driving around town, you are not alone. Many people would love to see this feature on their vehicles, as it would make the problem of where and when to charge an electric car go away. However, is it even possible?

Technology does not currently exist to allow an electric car to charge itself while it is being driven. Doing so would require perpetual motion to be a reality, but this would violate the law of physics. It is simply not possible to recover enough energy while driving to charge an electric car battery. 

There are so many benefits associated with owning an electric vehicle. Adding to that the ability to charge the battery as the car is being driven would be icing on the cake for many people. While this is not currently possible, it is important to understand why. Please continue reading to learn why electric cars cannot currently charge themselves while driving. 

Can a Generator Be Added to the Wheels of an Electric Vehicle?

It is theoretically possible to install a generator on the wheels or axles of an electric car. Some designers have proposed that a traction motor can be attached to one set of wheels to drive it. The generator can then be attached to the other axle. That would possibly allow that other wheels to generate the electricity necessary to charge an electric car battery. 

Another option would be actually to build a generator directly into the wheels themselves. Then, no matter how the generator ends up being attached to the wheels on a car, it can effectively convert the inertia generated from the vehicle’s momentum into actual electricity. 

Why Might This Help?

The idea of attaching a generator to the wheels is similar to the notion of regenerative braking. This has also proven to be an effective way of converting inertia into electricity. Remember that inertia is a way of measuring the resistance to a change in velocity. Momentum ends up being the combination of mass and velocity. 

As an electric car accelerates, its momentum increases. This will end up converting the energy that it has stored up and turning it into momentum. The opposite effect happens when the brakes are applied as the momentum decreases. This give and take could provide just the amount of electricity that is needed. 

How Would an Electric Generator Work?

If an electric generator were to be installed in an electric car, it would work by taking a wire and rotating it through a magnetic field. This would cause a current to flow through the wire. That current can be captured into a battery rather easily. This should provide enough energy to recharge the battery. 

The reason that this idea has been proposed about electric cars is that it would work in theory. The battery would be charged. It is the exact same concept as regenerative braking. 

What is Regenerative Braking?

Regenerative braking is already used in some models of electric cars. It allows the car to stop without there being any mechanical brakes installed on the vehicle. This would allow you to drive 20 miles down a mountain and effectively gain four miles of range on your electric car battery. 

For a generator to turn fast enough so that electricity is induced, momentum has to be first removed from the vehicle. When that momentum is removed, the car will slow down. This must be a continual process if you hope to have enough electricity generated for the battery to gradually recharge. 

Regenerative braking does work to charge a car battery, but it requires specific situations in order to work. You cannot depend on it to generate enough electricity to power a generator and then sufficiently charge the battery on each and every drive. It just is not useful for that purpose. While you can get a few miles of range in some cases, that is not enough. 

Would a Wind Turbine Do the Trick?

Another possibility proposed to charge the battery in an electric car while driving is to add a wind turbine to its design. A wind turbine is essentially a generator that has a propeller attached to it. 

Instead of trying to attach the generator to the wheels, the idea is to directly place the generator and the propeller in the air stream. If this were to be successful, then the air that flowed over the propeller blades would turn the generator. When the generator turns, inertia would be removed from the wheels. This is not the effect you are looking for. 

Why Won’t a Wind Turbine Work?

When it comes to electric cars, incorporating a wind turbine into its design would actually degrade the vehicle’s aerodynamics. A wind turbine is meant to be stuck into the airflow. This is necessary to make the generator turn enough that electricity is created. 

This would have the opposite effect than what was intended when trying to discover a way to charge electric car batteries while driving. Using a wind turbine would mean that the vehicle would require more energy to keep the car going, and this would drain the battery more than its current design already does. 

Why Aren’t Solar Panels Used to Charge Electric Cars?

This is another idea that has been tossed around before. However, there would need to be enough surface on the top of an electric vehicle to generate enough power. This would have to be done while driving at highway speed, which would be virtually impossible. 

Just getting the panels to be positioned such that the sun directly hits them when the car is parked would be difficult. It would be a monumental feat to do this while driving. It would simply not be able to capture the type of energy that an electric vehicle would need to run, much less to charge the battery while driving. 

What If There Was Enough Surface Area?

Let’s imagine for a moment an electric vehicle that is designed with an ample amount of surface area on top of the roof. As soon as you were to place solar panels up there, the aerodynamics of the car would suffer a similar fate as what would happen if a wind turbine were used. 

This would end up meaning that the car would have to expend even more power than it otherwise would have to. That would, of course, be defeating the purpose. As such, most people cannot foresee a way to use solar panels to allow an electric car to generate anywhere near the type of energy needed to be successful. 

An Interesting Note About Solar Panels and Cars

You might have heard of this idea of using solar panels to provide power to cars floated around before. That is because some solar-electric cars have been manufactured. However, they are only designed for solar races. They are not practical to use as passenger vehicles, so we are back to the drawing board yet again. 

Wrap-Up 

This explains why an electric car battery simply cannot be charged while you are driving around town. That is not to say that some new technology won’t come along in the future that makes this possible, but for now, we must revert to charging at home or via a station. Once you get used to that, the benefits of elective vehicle ownership are too many to count. 

Sources: 

https://easyelectriclife.groupe.renault.com/en/outlook/technology/self-charging-while-driving-electric-car/

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