What is Regenerative Braking in Electric Vehicles
10/24/2023 / Gail Alfar
Engineers and technologists are improving the automotive industry with electric vehicles that are increasingly efficient. One of the key technologies contributing to their energy efficiency and range optimization is regenerative braking. In this blog post, we will look at regenerative braking, how it works, and its role in enhancing the performance of popular EVs like Tesla, Ford Mach E, Rivian, Polestar, and almost all electric cars. Additionally, all 5000 Amazon Rivian electric delivery vehicles on the road and all Tesla Semi have regenerative braking.
Understanding Regenerative Braking
Regenerative braking is referred to by insiders as “one-pedal driving” because the vehicle slows down, or “brakes” when the accelerator pedal is released. In addition, this technology allows EVs to recover and store energy during the braking process. In conventional internal combustion engine cars, braking dissipates kinetic energy as heat through friction. In contrast, regenerative braking converts this energy into electrical energy. This process helps recharge the EV's battery and contributes to its efficiency.
How Regenerative Braking Works
When you slow an EV, the electric motor operates in reverse, effectively becoming a generator. The kinetic energy of the vehicle is converted into electrical energy. This electricity is then directed back into the battery for later use. The efficiency of regenerative braking varies among different EV models, with some offering more aggressive regenerative braking profiles than others. In a blog post on Tesla’s website, Greg Solberg provides an explanation of regenerative braking in the early Tesla Roadster.
Tesla Roadster Regenerative Braking
Solberg describes it as the process of converting the vehicle's kinetic energy into chemical energy stored in the battery. Regenerative braking also functions as a means of slowing down the vehicle. The term "regenerative" comes from the energy being recaptured and stored in the battery for future use. Solberg explains, “The kinetic energy possessed by a moving vehicle depends on factors like its mass and speed, as indicated by the equation E = ½mv². In simple terms, if a vehicle is twice as heavy, it possesses twice the kinetic energy. Likewise, if it's moving at twice the speed, it has four times the kinetic energy. When a vehicle decelerates, the kinetic energy it carries needs a destination for dissipation.”
In a traditional gasoline car, the majority of the kinetic energy is transformed into heat by the brake pads when the driver applies the brakes.
To understand regenerative braking further, we will look at how it applies to the Tesla Semi, a vehicle with a much larger mass.
Tesla Semi: A Marvel of Physics
The Tesla Semi can reach 500 miles of range. One obvious reason the range is great for the Semi is the advanced aerodynamics. Semi is built like a bullet, not a barn wall.