EV 101: How Do Electric Cars Work?

Posted on October 24th, 2022.

Eyeing a more environmentally friendly alternative to your gas-powered car? Electric vehicles are growing in popularity; here's how they get you from point A to B.

As manufacturing costs decline(Opens in a new window) and the charging infrastructure improves, electric vehicles (EVs) have become a more appealing purchase for US drivers looking to avoid sky-high gas prices or mitigate the environmental impact of gas-powered vehicles. But how do they actually work?

The Basics of Electric Cars

Unlike a typical internal combustion engine (ICE) vehicle that runs on gas, EVs don’t require explosive combustion via burned fuel to generate the energy needed to move. Instead, they use electrical energy stored in their battery packs to turn the electric motor (or motors) connected to the wheels and drive the car forward. As such, EVs have fewer moving parts than a gas vehicle, and generally require less maintenance, though they currently have a higher up-front cost.

There are several different types of vehicles that could qualify as EVs, a spectrum of cars from plug-in hybrids with small supplemental batteries to entirely electric, battery-powered vehicles, and even hydrogen fuel cell-powered cars. 

Most EVs you’ll see on the road today are either hybrids like the Toyota Prius or all-electric vehicles like the Tesla Model 3. We’ll focus specifically on how all-electric vehicles work here.

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The Science Behind the Battery

Every EV has a battery pack made up of groups of lithium-ion batteries, or cells, that supply the power needed for everything from moving the car to running the air conditioning. You’ll also hear this called a traction battery, and it's usually located at the bottom of the vehicle.

An electric car’s battery charges in much the same way the lithium-ion battery in your cell phone does, just on a much larger scale. You connect it to the grid via an outlet or charging station, and it draws energy until it’s charged. How much energy an EV's battery can hold will depend on its capacity, measured in kilowatt-hours (kWh). The higher the number, the higher the capacity, and the farther you can drive that EV on a single charge. 

Not all EVs have the same battery. Smart EQ(Opens in a new window) models from Mercedes-Benz, for example, have battery capacities of 16.7kWh, giving them about 60 miles(Opens in a new window) of range on a single charge. The Tesla Model S Long Range(Opens in a new window), on the other hand, has a 95kWh battery and an estimated 350-mile range. EV battery technology is constantly evolving, so we could see vehicles with longer range and shorter recharge times hit the market in the next few years.

Unlike the electricity coming from a typical wall outlet, batteries put out direct current (DC) power. In order to generate rotational force, that power needs to be converted to alternating current (AC). That’s where the design of an EV's motor comes in.

The Design of the Motor

An EV's electric motor doesn’t have to pressurize and ignite gasoline to move the car’s wheels. Instead, it uses electromagnets inside the motor that are powered by the battery to generate rotational force.

Inside the motor are two sets of magnets. One set is attached to the shaft that spins the car’s wheels, and the other is inside the housing surrounding that shaft. Both sets of magnets are charged so that their polarity is the same, and they repel one another. The force of the magnets pushing away from one another turns the shaft, spins the wheels, and moves the car forward. 

In order to maintain a constant state of repulsion between the magnets, their polarity has to constantly change as the shaft turns. Otherwise, they’d eventually rotate back to a point where they would attract instead of repel one another and lock themselves in place. AC power does this automatically, constantly alternating between positive and negative. But since the power from an EV’s battery is DC, a device called an inverter is needed to keep flipping the polarity of the magnets.

An EV's inverter flips polarity quickly, around 60 times per second, to keep the rotational force going. A separate DC converter(Opens in a new window) is used to direct power to other vehicle systems (heating, infotainment, and lighting) that don’t require alternating current. The frequency of the current sent to the motor can be changed by the driver, and the higher the frequency the more frequently the polarity flips. This generates more rotational force, or torque, and spins the wheels faster. 

The Art of Charging

With gas-powered cars, you fill up the tank and head out. With EVs, there are three different levels of charging stations in the US, from slowest (level 1) to fastest (level 3).

• Level 1 chargers are typical, 120-volt wall plugs, and are most useful in private homes where you can juice up overnight. It's slow: An 8-hour charge adds(Opens in a new window) about 40 miles of range; a full charge can take 20 hours or more.
• Level 2 stations step up to 240 volts and output anywhere from 10-25kW for a full charge in about eight hours. This makes them the common solution for overnight charging at home or at locations like hotels. Tesla Level 2 stations are known as Destination Chargers(Opens in a new window) (versus Superchargers). If you don't have the appropriate plug, a 240-volt outlet or home charging station would need to be installed to recharge an EV at your house.
• Level 3 DC fast charging (DCFC) stations deliver the most power; they can charge an EV battery to around 80% in about 30 minutes. They offer 50kW on average, though there are ones that funnel even more power into the battery, such as Tesla's Superchargers.

There's some debate(Opens in a new window) over whether using level 3 fast-charging stations all the time can have a deleterious effect on your EV's battery. The jury's still out(Opens in a new window) on that one; for now, you should probably just use what makes the most sense for you based on where you live and what you can afford.

Most EVs come with a power cord that can plug into level 1 and level 2 charging stations, the two most common charging levels you’ll find. Teslas also come with an adapter that can be used at non-Tesla stations (mobile chargers are no longer bundled). Most public charging stations will have a group of connection ports that deliver level 2 and 3 power. 

Rather than depleting the battery and filling it up all at once, many EV drivers will top up the battery while the vehicle is parked throughout the day—at work, running errands, or at the gym. This prevents the battery from losing too much charge throughout the day and means less time charging the vehicle or sitting at a charging station.

EVs also come with a regenerative braking system that harnesses kinetic energy from stopping the car and channels some of it back to the battery pack to be stored as electrical energy. This won’t totally recharge your EV but can make it much more efficient in the right circumstances.

How Far Can an EV Get on a Charge?

The most common EV concern is range anxiety. Will an EV will get the same mileage on a charge as a gas car gets on a full tank? The answer is: It depends.

The average EV range at the time of this writing is 200-250 miles(Opens in a new window) on a single charge, according to data aggregated by Electric Vehicle Database. But the upper and lower ends of the spectrum vary widely, from 50 miles to over 300 (the Lucid Air promises(Opens in a new window) 500+ miles). Multiple variables can affect that range, both in the moment and over the lifetime of the vehicle.

The size of an EV’s battery is one of the most consequential factors when it comes to range. But whatever its capacity, an EV’s range can be reduced by continuous highway driving, frequent quick accelerations, overuse of fast charging, extreme weather, and natural aging over time. 

Modern electric cars are fairly competitive with gas vehicles, and are getting more so every year. Their range is already comparable to a gas car on average, and charging infrastructure is plentiful enough in many areas that EVs are becoming a viable option for drivers looking for low-emission vehicles. EVs have some kinks to work out, and won’t save us from climate change by themselves, but they can be part of a larger comprehensive movement to rethink transportation and build greener alternatives.

Text and image source: PCMag.