How does regenerative braking boost efficiency?

One of the most advantageous attributes of both electric and hybrid vehicles is their regenerative braking systems. When a driver hits the brakes in a conventional vehicle, it produces excess kinetic energy which simply dissipates as heat. In the regenerative system, however, that energy is harnessed and sent to the car's battery.

HEVs rely on this stored energy for power, allowing them to run without needing periodic recharges. EVs use it to supplement the supply they receive from recharging. Although regenerative brakes don't benefit all drivers, the potential advantages are remarkable: Some owners of electric vehicles report driving twice the distance before their brakes need standard maintenance work.

How does it work?

Regenerative braking systems are exclusively used in EVs and HEVs. Although they still utilize conventional hydraulic brakes, electric motors are actually at the center of the braking process in these vehicles, working by putting the engine in reverse once the brakes have been hit. This process produces kinetic energy which is then captured and stored in the car battery as electricity. This helps to supplement the electricity reserves in the batteries of EVs, while providing HEVs with enough energy to forego lengthy recharging entirely.

This system differs from its traditional counterpart in fundamental ways. Instead of reversing the motor, conventional braking systems rely on a complex system of pads and rotors to physically bring the vehicle to a stop after the driver steps on the brake. Like regenerative brakes, this action creates friction which generates kinetic energy but, without a mechanical system in place to capture that energy, it is usually lost as heat.

A man drives a vehicle.Regenerative systems extend the lifetime of brakes.

What are the advantages?

The efficiency of regenerative braking depends heavily on the type of vehicle and each individual owners' style of driving. Naturally, vehicles that produce more kinetic energy will maximize the amount of electricity that can be stored. This includes larger vehicles whose braking systems must exert more energy to stop the sheer momentum they create, as well as smaller vehicles that are more frequently in stop-and-go traffic due to the repetitive brake use.

Additionally, vehicles that engage in more downhill driving will experience the benefits of regenerative braking more than those that do not. Figures provided by Eletrek show that regenerative brakes are around 60-70% efficient.

More than that, because regenerative braking systems rely on the motor itself more than they do separate components, the brakes are far more durable and require less frequent maintenance. In a survey conducted by TorqueNews, 60% of Prius owners said their cars notched 100,000 miles before requiring standard brake maintenance, while 20% said the same parts didn't need replacing until after 200,000 miles. For comparison, traditional brakes typically need to be changed after 50,000 miles, demonstrating an enormous boost in longevity.

What about the disadvantages?

Because the efficiency of regenerative brakes is dependent on every drivers' own behavior, they don't always have the same advantages. Driving long distances at steady speeds — like that typical of highway driving — causes an electric motor to expend energy without receiving recycled energy in return from the regenerative braking system, creating an energy demand that cannot be met internally.

Similarly, drivers that stop abruptly while driving at high speeds instead of gradually coming to a steady stop force the vehicle to use their faster-acting conventional brakes. The results are the same: Bypassing the regenerative system means the vehicle is unable to capture the kinetic energy produced by the brakes, substantially reducing their efficiency.

Technology for better-performing vehicles

Still, regenerative braking is an incredibly effective feature of EVs and HEVs. By capturing energy created by the vehicle itself, they maximize efficiency and reduce the need both for wasteful hydraulic brakes as well as frequent charging sessions. More than that, they reduce the pressure that frequent stopping can place on hydraulic braking systems and massively increase the strength and resilience of EVs and HEVs.

High-performing braking systems are indispensable to a vehicle's effectiveness and longevity. Greening Testing Laboratories is a fully certified brake testing lab that provides a variety of brake testing services worldwide. Contact Greening for a complimentary consultation.