Electric vehicles (EVs) are a growing industry. While they still represent only about 2% of the new vehicle market in the United States, sales in Europe and China are rising steadily. Given current rates of growth combined with government policies, the global number of electric vehicles on the road is projected to expand from 8 million in 2019 to 50 million by 2025 and close to 140 million by 2030. Many (but not all) major automotive manufacturers have been aggressively attempting to adapt to this all-electric trend.
Maybe not so shockingly (pun intended), many drivers don’t know how an electric car actually works. For many, the knowledge spans as far as plugging it in, letting charge, and driving it off. It’s not really as simple as that, even though an electric motor is comprised of far fewer moving parts than a traditional internal combustion engine. A video from “Learn Engineering” looks to explain what’s actually going on underneath all the clockwork and introduce the masses to a world of electric propulsion. The video presentation tears down a standard Tesla Model S, no doubt the world’s most well-known electric car, and provides a slightly awkward voiceover to deliver the knowledge. Get past the odd narration and the information is pretty valuable, however.
Components such as the induction motor, inverter, transmission, differential, battery pack, synchronized vehicle mechanism, and regenerative braking system are all awarded a deep dive in the name of electric vehicle education. We learn that the motor is efficient over a wide range of operating conditions and that the inverter can vary the frequency and amplitude of the AC power it feeds to the motor, thus controlling how much power the car receives. The upshot? An electric motor needs only a single-speed transmission. Additionally, the video looks at how Tesla, in particular, builds its batteries. Tesla uses thousands of small cylindrical lithium-ion cells, passes liquid glycol through tubes between the cells to cool them, and mounts the battery pack beneath the cabin floor. Some automakers opt for large, rectangular cells.
Key Components of an Electric Vehicle
Electric vehicle developers have worked hard to replicate the look and feel of gas-powered cars. Some models even have imitation grills on the front of the car, even though they are completely nonfunctional. There are some three-wheeled or futuristic-looking electric vehicles on the market, but most of what typical drivers immediately see both inside and outside an electric car will look familiar — body upon a chassis, four wheels, windows, seats, steering wheel, glove box — unless they look more closely.
Under the Hood
Open up the hood, and the differences are obvious. There is no engine, no radiator, no carburetor, no spark plugs. Depending on the model, electric vehicles can have as few as 30-40 moving parts, while a gas-powered car can have 2,000 or more, greatly decreasing the repair costs for an EV. Where an engine normally would be, some EVs have a front trunk suitable for a couple of bags of groceries. All that empty space adds safety to an electric vehicle, giving it a larger crumple zone better able to absorb the force of a head-on collision.
Underneath the Car
Look underneath the rear of the car, and you’ll see no tail pipe. Since there is no combustion engine, there is no need for an exhaust system, or for a muffler to reduce the rumble of the engine. New EV drivers are surprised at how little vibration or noise their vehicle gives off; when the vehicle is stopped at an intersection, only the lights on the control panels let you know it is still on.
With zero tailpipe emissions, electric vehicles help reduce one of the leading causes of climate change: greenhouse gases from the transportation sector, which accounted for 28% of total U.S. greenhouse gas emissions in 2018. In many parts of the world, coal is still a leading source of electricity production, so depending on the source of electricity, EVs might not be completely emission-free. Yet even if the electricity in an EV battery was created by burning coal, EVs still produce far fewer emissions than gas-powered vehicles. And as the electricity grid relies more and more on low- or zero-emissions sources, that difference will only grow wider.
What you will notice underneath the car is a large electric battery, which stores the energy necessary to run the vehicle. The battery is actually a pack of many smaller lithium-ion battery modules, themselves made of individual battery cells (about the size of a AAA battery), and linked together in electrical circuits that are managed electronically to deliver the maximum power in the most efficient way possible. Battery technology is advancing rapidly, with new chemistries and different manufacturing processes, all geared toward increasing the battery’s energy density while lowering the cost of the most expensive part of the vehicle.
One of the dangers of all lithium-ion batteries is “thermal runaway” leading to explosive fires, so the battery pack is cooled with a thermal management system and a protective casing. Electric vehicle fires attract media attention because of anxieties about new technologies; meanwhile, there are approximately 166 gasoline car fires a day in the United States. Battery-driven cars are far less likely to catch fire than cars that are by definition based on the combustion of flammable liquids.
A motor in an electric vehicle follows the same principle in use since the 19th century: convert electricity into mechanical energy. It does so when electricity is sent from the battery to a stationary part of the motor (the stator) that creates a magnetic field that turns a rotating part (the rotor). The spinning rotor is what creates the mechanical energy that spins the car’s wheels using a single gear. The more electricity, the faster the rotor turns, and since there is no shifting between gears in electric vehicles, and acceleration and deceleration involve smooth transitions between speeds.
While a gas-powered car can only have one combustion engine, an electric vehicle can have multiple motors, which can act independently. A dual-motor vehicle has one motor dedicated to city driving and another motor (often called an induction motor) dedicated to higher speeds. Four-wheel drive is common in electric vehicles because each wheel can have its own motor, increasing maneuverability and traction, and can even allow the tires to rotate in different directions.
Electric vs. Gas Cars
If most of the physical differences between electric and gas-powered cars are under the hood or out of sight, so too are the differences in which the different types of vehicles are driven, fueled, and maintained.
Driving an electric vehicle is nearly the same as driving a gas-powered vehicle, with a few differences that drivers will notice immediately and adapt to relatively quickly. Electric vehicles are known for their quick-off-the-blocks acceleration, and instant forward propulsion is perhaps the first thing that new drivers recognize in an electric vehicle. Torque is the force that produces rotation — in this case, of a car’s motor, expressed as rotations per minute (RPMs). Because gasoline engines start at low RPMs and increase through incremental gear shifts, there is a lag in reaching maximum torque.
In an electric vehicle, however, maximum torque is reached immediately upon pressing on the accelerator (not the “gas pedal”), thrusting the car forward and the driver back against their seat. Some electric vehicles have the highest 0-60 acceleration in their vehicle class, which is especially useful in entering highways, passing slower vehicles, and avoiding accidents.
In a gas-powered car, an alternator takes energy from the rotating wheels to charge the car’s relatively smaller battery. When a driver begins braking in an electric vehicle, “regenerative braking” draws energy from the vehicle’s momentum to generate electricity and send it back into the battery, extending the range of the vehicle. Driving in regenerative braking mode means every time you take your foot off the accelerator, the vehicle slows down more rapidly than in a gas car. While the car won’t come to a complete stop, regenerative braking allows for “one-pedal driving,” where the brake pedal is less frequently engaged, saving wear-and-tear on the brakes.
With a large, heavy battery running along most of its base, an EV has a lower center of gravity than most gas cars, which improves handling around corners and in slippery road conditions. This also makes rollovers less frequent, improving the car’s safety.
The most fundamental difference between an electric vehicle and a gas-powered one is, of course, the energy source. Instead of a gas tank, somewhere on an electric vehicle will be its charging port (or ports, since there are multiple ways to charge an EV). Even the fastest-charging electric vehicles take longer to charge than it takes to fill up a tank of gas. However, 80% of EV charging is done at home, overnight, in the same way one would charge a phone, so charging speeds are more relevant for long-distance trips and for people who cannot charge at home. By contrast, assuming a typical consumer fills up their gas tank three times a month and spends five minutes at the gas station each time, they spend a total of three hours a year in all types of weather pumping gas — none of which can be done while they are sleeping. An EV driver usually spends no more than a few seconds plugging in and going inside.
Electricity can easily flow in and out of an electric vehicle, unlike gasoline, and one emerging technology is vehicle-to-grid (V2G) or vehicle-to-home (V2H) capability. In theory, EV batteries could be used to power a household during a power outage, or supply electricity to the grid to improve its efficiency and stability and earn the EV owner money. Not all EVs are equipped with this ability, however, and some EV manufacturers prohibit it and will void an EV owner’s warranty if it is used, since frequent discharging of a lithium-ion battery will decrease its life expectancy.
Tune-Ups and Repairs
Since the primary function of an electric vehicle is moving electrons around, it is more like a computer on wheels rather than a mechanical device (an engine) on wheels. Like digital device manufacturers, some EV manufacturers send over-the-air software updates to improve the efficiency of or add new features to their vehicles. This not only extends the life of the vehicle and decreases its operating expenses; it can also increase the resale value to the car over time. With an EV with few moving parts, “e-Tune-ups” may be more frequent than visits to the repair shop. According to research by Consumer Reports, “EV and plug-in hybrid drivers pay half as much to repair and maintain their vehicles. Consumers who purchase an electric car can expect to save an average of $4,600 in repair and maintenance costs over the life of the vehicle compared with a gasoline-powered car.”
Electric vehicles may not be for everyone, and much skepticism abounds about them. Much the same was said about motor vehicles in the early twentieth century when gasoline and the Model T revolutionized transportation: “I do not believe the introduction of motor-cars will ever affect the riding of horses,” said British Member of Parliament Scott Montague in 1903.10 Electric vehicles are already disrupting the automotive industry. The next decade will determine whether or not gas-powered vehicles go the way of the horse.
With the market’s demand for electric cars only expected to grow, it’s not a bad idea to brush up on life sans gasoline-powered engines. This video makes the bold prediction that electric motors are expected to make their internal combustion counterparts obsolete by 2025. That may be too soon, but this video is worth a look anyway. Watch it and when our electric overlords come, you will know how they work.