How often have you had conversations with friends about electric vehicles where you talked about their engines? Here's a fun fact. EVs do not have engines. They have motors or, to be more specific, electric motors. It's not a question about terminology; engines and motors are completely different, in the way they are built, and the way they work.
Fewer moving parts mean less wear and tear, making electric motors more reliable as well as cheaper to maintain, compared to internal combustion, or IC engines. They age well, too. In fact, a high-mileage electric car is basically as efficient as a brand new one. Electric motors have other advantages over engines, such as the ability to deliver instant torque and emit zero tailpipe emissions, which make them beneficial for the environment.
At a fundamental level, an engine converts chemical energy into mechanical energy. It involves a combustion/burning process where heat and pressure are generated, which offers the driving mechanical force. This combustion can be achieved by different kinds of fuels like gasoline, diesel, and hydrogen. A motor requires only electricity to run.
A motor, unlike an engine, converts electrical energy into mechanical energy. The primary source of energy here is electricity, which is sourced through batteries or generators. Unlike engines, which use combustion to generate power, motors use magnetic fields to spin a rotor. In many ways, electric motors in cars are similar to the ones you see in ceiling fans and washing machines. Or they are like Koenigsegg's tiny 63 pounds electric motor that's an absolute monster with 335 horsepower and 443 lb-ft of torque on tap.
When we break it down, a typical Internal combustion engine has fixed and moving parts. Fixed parts include a cylinder and a spark plug in the case of a gasoline engine. Moving parts include valves, a piston, a connecting rod, and a crankshaft. In an IC engine, the chemical properties of a fuel, like their flammability, flash point, and auto ignition temperatures, and a spark in the case of gasoline engines, cause combustion inside a cylinder. This combustion or explosion generates heat and pressure, which moves the piston inside the cylinder downward. The piston is connected to the crankshaft via the connecting rod and converts the up and down (reciprocating) motion of the piston into rotary movement for the final drive.
An electric motor's workings are comparatively simpler, with far fewer moving parts. It contains two primary components, a stator (fixed part) and a rotor (moving part). Then, of course, comes the fuel, which, in this case, is electricity supplied from a battery pack. Think of the stator as a hollow iron or steel tube (core) with copper wires (coil) wound inside it. These wires are connected to the car battery. The rotor, on the other hand, sits inside the hollow tube (stator). It is a solid metal tube with permanent magnets attached to its circumference. When electricity is supplied to the stator coils, a revolving electromagnetic field is created, which produces a pulling force on the magnets on the rotor, causing it to spin. This spinning motor offers movement to the final drive. The speed of the motor is controlled by the current supplied to it.
Electric motors offer a distinct advantage over ICE engines. Fewer moving parts equate to better efficiency. In fact, an electric motor can convert 90% of the electrical energy supplied to it into mechanical energy. In comparison, modern combustion engines can offer a maximum efficiency between 25% to 35%. This is because IC engines lose most of their chemical energy due to the heat produced and the friction between moving parts. In fact, most modern EVs come with regenerative braking, which converts the kinetic energy recovered during braking into electrical energy, using it to recharge the battery and making electric motors quite efficient. That said, regenerative braking could make your kid fail their driving test.