What is regenerative braking and how does it work?

If you’re thinking of buying an electric car but haven’t driven one before, you might have heard or read the term 'regenerative braking' and wondered what it means.

Well, regenerative braking is one of several factors that make electric cars quite different to petrols and diesels to drive, and it's arguably the most significant. (The others include the lack of engine noise, the instant power delivery and the fact that there’s usually just one forward gear.)

That's because, if you choose to use it, regenerative braking can affect the way you drive. So, here we explain what it is, how it works and how it can benefit you and your car.

What is regenerative braking?

Commonly referred to as ‘regen’ braking, it's a process an electric car uses to regain kinetic energy that would otherwise be lost during braking. The energy is returned to the car's main battery as electricity so it can be used to drive the wheels.

Some plug-in hybrid and hybrid cars have regenerative braking too. While the system is essentially the same as you’ll find in an electric car, they use it to help reduce the amount of fuel the engine needs to burn.

How does regenerative braking work?

The beauty of an electric motor is that it can run either forwards or backwards (or, strictly speaking, clockwise or anti-clockwise). In normal driving, the motor is rotating in the same direction as the wheel or wheels it drives, but under braking, it can spin in the opposite direction, generating energy. 

In a car with a combustion engine, when you press down on the brake pedal, hydraulic pressure pushes the brake pads on to the discs, creating friction and slowing down the vehicle. During the process, energy is wasted (although some new petrol or diesel cars now have a limited form of 'regen').

Most electric cars, hybrids and plug-in hybrids have a hydraulic system and regenerative braking. One benefit of having two braking systems is that it reduces the wear on parts, which can save you money and lower maintenance costs.

What does regenerative braking feel like?

Regenerative braking feels like someone is gently applying the brakes as soon as you take your foot off the accelerator pedal. It can feel rather odd to start with, but after a few miles it becomes second nature to many drivers.

Many systems allow you to alter how aggressively the regenerative brakes are applied. In the gentler settings it delivers a feeling akin to lifting off the accelerator as you’re driving uphill. That sensation is more pronounced as you choose fiercer settings, and can be similar to the feel of engine braking.

Do I need to drive any differently?

You only need to drive differently if you want to. Keep the braking force off, or at its lowest setting, and you’ll be able to drive as you would in any other car. Turn up the effectiveness and you’ll find yourself using the brake pedal less and less. It requires a bit of mental recalibration, and a bit more thinking ahead, but you should quickly find a setting that works for you.

The only other thing to bear in mind is how to cycle through the various settings. On many cars this is done through buttons or paddles mounted on or behind the steering wheel.

Are all systems the same?

All regenerative braking systems do a similar job, but the methods you'll use to vary the braking force varies.

In the Kia EV6 for example, you have five settings of regenerative braking, and you can switch between them using paddles behind the steering wheel. The lowest setting – called ‘0’ – switches the system off so you can use the hydraulic brakes as you would in a petrol or diesel car. There’s also ‘1’, ‘2’, ‘3’ or the maximum, ‘i-Pedal’. The i-Pedal setting is so strong that you hardly need to touch the brake pedal at all.

In the MG ZS EV there are only three settings, and you can select them using a switch on the centre console. In this instance, you have ‘Light’, ‘Moderate’ and ‘Heavy’.

What is one-pedal driving?

One-pedal driving is a more extreme form of regenerative braking which can stop the car relatively quickly and bring it to a complete stop if necessary without you needing to press the brake pedal.

With a little more anticipation, it can be perfectly possible to drive around town without touching the brakes at all. Of course, if you need to stop suddenly you can do as you would with any other vehicle.

Which is the best setting for regenerative braking?

The best regen setting really depends on your driving style and the kind of roads you’re driving on. Some find more aggressive settings a little too intrusive – if you do, try turning down the assistance. In this regard, it’s really a matter of personal preference.

Traffic conditions play an important role in the mode you should select. If you’re driving around town, then using the strongest regen settings can allow you to make relaxed progress – and increase your range – without the need to continually press the brake pedal. On a motorway, it might be better to use one of the weaker settings to allow the car to coast a little more.

Do all electrified cars come with regenerative braking?

Most new electric and hybrid cars come with some form of regenerative braking to help conserve energy. However, you can’t always adjust the strength of it.

So, if you’re looking to buy an electric car, it’s important to check what kind of regen system the car has before you drive it.

Can it improve my range?

Regenerative braking is an effective way of reducing a car’s energy consumption. So, if you’re looking to maximise the range of an electric car, using the strongest setting can help conserve more energy.

Will my brake lights come in when using regenerative braking?

Whether your brake lights will come on depends on how much you’re slowing. If you gently reduce the pressure on the brake pedal, it’s unlikely the lights will come on. But if you remove your foot from the accelerator pedal completely, which will start the active braking forces, then the lights will illuminate.

It’s worth remembering this, to avoid unnecessarily flashing your brake lights to those behind.

Pros and cons of regenerative braking

Pros:

• Reduces the need to press the brake pedal, and can make driving in congested traffic more relaxed

• Limits wear and tear on the braking system

• Can help to increase the car’s range without the need to plug in

Cons:

• Can reduce the communication between your foot and the brakes when you press the brake pedal

• Can take a little getting used to

• Not all systems have a wide range of adjustment in braking force

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