How do electric cars work?

It is much easier to take it for granted that a modern car moves us around than it is to understand how it works.

For almost 150 years now, the internal combustion engine has been the default choice for propulsion despite its massively complex arrangement of moving parts.

We all know that a car requires filling it with highly-flammable fuel that explodes somewhere in the engine in order to spin things which make the wheels turn.

Other than that, it may require a degree in science, physics or engineering – or years of training as a mechanic – to fully comprehend how two tonnes of metal, plastic, glass and rubber manages to get you to work and back every day.

Electric vehicles, which are increasing in both popularity and prevalence, might seem to be more complicated machines because they are so new and because car-makers are filling their websites with jargon and using a different set of numbers for performance parameters.

But the fact is that battery-powered vehicles are far simpler than combustion-engined cars in their mechanical make-up.

At its core, an EV applies the same basic principle as any other vehicle. It uses a source of stored energy to create motion by feeding a motor which produces enough torque to turn a driveshaft that is connected to rotating wheels. Simple.

In either case, the driver dictates how much energy is provided to the motor by pressing the accelerator pedal – just like the flow of water when opening a tap – in order to produce more, or less, power as required.

However, while the principle, the action and the results are the same, the parts and the process are entirely different.

So how does an electric car work?

For starters, an EV replaces gasoline for electrons as the energy source which is stored in a battery pack instead of a petrol tank.

Almost exclusively, electric vehicle battery packs are made from a collection of lithium-ion cells, which are highly effective at dispersing power (a good flow rate) and being rechargeable (meaning they can be ‘refuelled’) over extended time periods.

They also have high energy density (the amount of electricity they can store in the space they take up) and a low static discharge rate (they don’t leak power when not in use).

Like a petrol tank, the amount of electricity that can be stored is dependent on the size of the battery, but the capacity is measured in kilowatt-hours (kWh) rather than volume (litres).

The battery obviously depletes when energy is drawn from it to power the electric motor and it can be replenished when plugging it into a power source, either at home via a household power point, through a higher-voltage wallbox or via a growing network of high-speed public charging stations.

A significant advantage of driving an electric car is the ability to capture kinetic energy while the vehicle is decelerating and feed that power back to the battery, essentially producing free fuel – an impossibility with a petrol-engined car.

It can do this by reversing the rotation of electric motor when slowing down, which produces – instead of consumes – power and is then transferred back to the battery.

An electric vehicle is powered – obviously – by an electric motor. But just as it is with combustion engines, there’s a number of a different types, each with their own unique characteristics that suit different applications.

Electric motors (or traction motors) can be designed to operate on either DC (direct current) or AC (alternating current) power sources, with the latter being the most common application in electric cars due to their regenerative braking ability while also being more reliable and requiring less maintenance.

The traction motor is provided power by the battery via an inverter (which converts the current from DC to AC), which then spins an output shaft that delivers torque to the transmission.

Due to the fact that electric motors are physically smaller than combustion engines – and require no auxiliary cooling systems and radiators – they can be positioned at either the front or rear of the vehicle, or in a twin-motor configuration.

On top of that, and because they deliver maximum torque from zero revs with instant response, the power delivery can be precisely controlled for maximum traction and stability.

More than anything, electric motors do not directly produce any emissions.

The final cog (pun intended) in the machine is the ability to transfer the rotational energy from the electric motor to the wheels, which requires a transmission.

However, unlike a combustion engine which only produces maximum power across a relatively small rev range and is limited in its speed, thereby requiring a transmission with a series of gear ratios in order to travel efficiently across different speeds, an electric motor can rev freely up to 20,000rpm while producing the same amount of power.

Consequently, most EVs simply feature a single-speed gearbox and an open differential with drive shafts to the wheels.

Some newer high-performance models, such as the Porsche Taycan, have a two-speed gearbox for better performance.

So, there you go, a basic understanding of how an electric car works – the same principle, but a totally different process.