How do electric cars work? A basic introduction

Electric vehicles are more prevalent now than ever as sales continue to increase. But how do they work? In this guide, we explain what happens under the hood (and under the seats) of an all-electric car.

Credit: Chesky with Getty Images

The electric drivetrain

There are certain parts that electric vehicles can't do without: the giant battery and motor, for starters. The battery, known as a traction battery pack, is not like the 12-volt lead-acid starting, lighting and ignition (SLI) battery in a gasoline-powered car. The traction battery is much larger, forcing EV manufacturers to hide it under the seats. SLI batteries supply short-term electricity to the starter motor of a gasoline vehicle, igniting the spark plugs and therefore the engine. In contrast, traction batteries provide constant electrical currents for several hours.

Most traction battery packs are made up of several modules, each containing hundreds of individual cells. Each cell contains an anode (a negative electrode), which passes ions through the cell's liquid electrolyte to a cathode (a positive electrode). The electrons produced by this process travel through an external circuit, powering whatever device the pack is connected to. When the traction battery pack is connected to an external charging source (such as an electric vehicle charger), the opposite occurs: the cathode sends electrons back to the anode.

Lithium-ion batteries, the most common battery in electric vehicles, can only accept direct current (DC) power. But the most reliable electric vehicle motors can only draw power from alternating current (AC). This means that today's electric vehicles require an inverter, which converts the DC from the battery pack to AC. The inverter does this by passing DC through the primary coils of its transformer. An electronic switch powered by a semiconductor The transistor array reverses the direction of DC flow back and forth, creating AC in the secondary coils of the transformer. The inverter then sends the AC to the vehicle's electric traction motor. (The inverter also has another important function, but we'll get to that in a moment.)

When AC reaches the motor, its electrons create a magnetic field. Because the current is alternating, the north and south poles of the magnetic field exchange back and forth, creating a rotation that stimulates a free-floating rotor in the motor's stator. The rotor rotates, moving an axle that causes the vehicle's wheels to rotate. The speed at which the wheels rotate is controlled by the inverter, which is responsible for managing the frequency of the electric current. The higher the frequency, the faster the rotor spins, resulting in faster rotation of the wheel.

Credit: Bram Van Oost/Unsplash

Peripheral components

So what about all the other things in an electric vehicle? Today's electric cars mean little without their infotainment interfaces, climate control systems and other amenities, which also need power. Instead of drawing electricity from a small SLI battery (like in a gasoline vehicle), these systems draw power from the aforementioned electric powertrain. They don't do much to reduce the range of an electric vehicle, although heat and air conditioning may have a slightly greater effect.

Range is generally referred to in terms of distance per charge. If an electric vehicle has a range of 300 miles, a fully charged traction battery can keep the vehicle running for up to 300 miles before running out of power. A few things can affect the range of an electric vehicle, from carrying heavy material to driving in cold weather. This doesn't mean drivers living in cold climates can't use an electric vehicle for work or pleasure; it just means they may have to pay more attention to their routes and the locations of the nearest chargers.

Credit: Robert Linder/Unsplash

Charging

Speaking of chargers, electric vehicles can't do much without them. Some are connected to the mains, while others connect through a standard household outlet or a 240-volt circuit. (Your electric stove or clothes dryer probably uses the latter.) We've already discussed the way electrons flow through the cathodes of battery cells and onto the anodes when an electric vehicle is charging, but even that process is variable and gets slower or faster depending on the vehicle. type of charger used. This is because different chargers are capable of generating different energy outputs.

Level 1 The chargers, which plug into a typical 120-volt household outlet, offer power of about 1 to 2 kilowatts (kW). This means that the average electric vehicle battery pack will take between 30 and 50 hours to reach 80% of its capacity for current vehicles, which is too slow for most purposes.

Level 2 Chargers, which can be hard-wired or plugged into a 240-volt circuit, offer a much more impressive 7 to 19 kW of power. This will boost the average EV battery up to 80% in 4 to 10 hours, making it the ideal charger for shopping malls and residential garages.

Level 3 Chargers, known as DC fast chargers, such as the Tesla Supercharger, bring the average electric vehicle battery to 80% of its capacity in less than an hour, thanks to their power of 50 to 350 kW.

Tesla Superchargers require a proprietary connector (NACS), but the company has pushed to make it the new standard. Starting in 2024, Ford, GM, Mercedes, Rivian and Volvo vehicles will work with these chargers via an adapter for your existing CCS ports. These same brands commit to incorporating the connectors directly into their vehicles starting in 2025.

Beyond gaining a deeper understanding of a rapidly expanding market, learning how an electric vehicle works can help you determine if you will one day want one. If you are still undecided, we recommend looking at electric cars. Impact on the environment compared to gasoline cars.