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What is a battery electric car (BEV) and how do electric cars work?

What makes electric cars – properly referred to as battery electric vehicles (BEVs) different from petrol and diesel vehicles? And how do electric cars work? Here are the answers

In February 2021, while car sales in the UK fell by a third overall, sales of electric cars – also known as 'battery electric vehicles', or BEVs – nearly doubled compared to the previous year. Plus, with the UK government set to ban the sale of new petrol and diesel cars by 2030, carmakers are responding by investing billions in new electric cars. So it's likely that making the big switch to electric will be a consideration for many UK car buyers. Here, we explain what an electric car is and how they work.

How do electric cars work?

The biggest difference between an electric car and a normal diesel or petrol-engined one is that, in an electric car, the internal-combustion engine has been replaced with either one or multiple electric motors, fed by a large lithium-ion battery pack instead of a fuel tank.

An electric car is driven by the electric motor(s), and in the same way a regular engine uses diesel or petrol from the fuel tank, an electric motor consumes electricity stored in a battery pack. Lithium-ion batteries are by far the most common type used in electric cars: these store electricity obtained from the grid by charging through a cable. Much like charging a mobile phone, an electric car is plugged into the grid, through either a home wallbox or a public charging unit.

The power from the battery is delivered to the electric motor through a controller, which in turn is connected to the throttle. The amount of throttle movement determines how much power the controller sends to the motor, which then determines how fast the car moves. Most electric cars also come with regenerative braking technology. With this, lifting off the throttle forces the electric motors to effectively run in reverse, recovering energy that's then converted into electricity and transmitted back into the car’s battery.

This has the effect of slowing an electric car down, and on some cars – such as the Nissan Leaf – it's strong enough to bring the car to a complete stop. Nissan calls its version the 'e-Pedal': the blanket term is 'single-pedal' driving, and cars that offer it can be driven almost without using the brake pedal at all.

Unlike normal cars, electric cars do not feature a gearbox with multiple gears. This is because an electric motor delivers its maximum torque immediately and doesn’t need to be revved. Electric cars also have a much larger working range than those with internal-combustion engines, so they don’t need gears to optimise performance and economy.

Advantages of electric cars

Electric cars have many advantages. The two biggest ones are much lower running costs than internal-combustion cars and zero tailpipe emissions. The first of these comes from the fact that electric vehicles don’t rely on diesel or petrol as their fuel, but on electricity, which is much cheaper. While a litre of petrol or diesel costs on average £1.30, electricity costs just over 14p per kilowatt-hour. And although litres and kilowatt-hours aren’t directly comparable, you can compare the cost per mile to see just how efficient an electric vehicle is.

A full charge of a Kia e-Niro – which has a 64kWh battery – should cost around £9: with a range of 282 miles on paper, this works out at three pence per mile. In contrast, an equivalent petrol or diesel car would cost some 12p per mile, which means you could save £27 for every 300 miles of driving. Over the course of a year, that really adds up. According to the Government’s Go Ultra Low campaign, owners reported annual savings of over £3,000 in running costs and tax receipts.

The second advantage is a lack of tailpipe emissions. While normal cars emit carbon dioxide, nitrogen dioxide and other harmful pollutants, the tailpipe emissions from electric vehicles is zero. Not only does this improve air quality in busy city centres, but it also means owners of electric vehicles don't pay any vehicle excise duty (VED), or road tax.

Electric vehicles are also exempt from other taxes such as the London Congestion Charge (until 2025) and the Ultra Low Emissions Zone payment. And in the 2021/22 financial year, company-car Benefit-in-Kind tax on electric cars is 1%, potentially saving thousands.

Disadvantages of electric cars

One of the big concerns for any potential electric-vehicle owner is how far they can drive – the car's range. Early models had less than 100 miles of real-world range, often inducing a condition known as ‘range anxiety’ in drivers. But more modern electric vehicles such as the 62kWh Nissan Leaf e+ come with a lab-tested range of nearly 240 miles, which translates into around 210 miles in real-world driving. Yet that's still less than what conventional diesel and petrol cars can achieve.

More expensive models like the Jaguar I-Pace and Tesla Model S come with 250 or 300-mile-plus ranges, but these cost significantly more than a more affordable electric car such as a Renault ZOE. Check out our list of the longest-range electric cars here. Another disadvantage is charging time. A full charge of a standard 40kWh Nissan Leaf takes over 13 hours using a normal, three-pin plug. Even a 50kW fast charger takes over half an hour to charge the car. Conversely, a petrol or a diesel car is far quicker to fill up.

Pros and cons

Whether an electric car is right for you is ultimately for you to decide. But it’s worth considering the following points. What kind or size of a car do you need? Do you do a lot of driving daily? Is your commute something that could feasibly be covered by an electric vehicle?

Also consider whether or not you have the facilities and space to charge an electric vehicle at home. After all, current estimates show that 90% of all electric vehicles are charged at home. Do you have a garage or a driveway where you can plug in an electric vehicle? Could you install a home wallbox charging unit? These will help speed up the charging.

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