All electric and plug-in hybrid vehicles on the market today in the U.S. have a regenerative braking system. Some conventional hybrids do as well. If you’re shopping for a hybrid or electric vehicle, and you’re wondering what that is and how it works, you’re in the right place.
What Are Regenerative Brakes?
Regenerative brakes use electric motors rather than a traditional friction braking system to slow down and stop a car.
With a traditional hydraulic braking system — usually disc brakes or drum brakes — braking wastes energy. It takes the kinetic energy moving your car forward and turns it into heat rather than motion. Although it’s effective at slowing down a moving vehicle, the heat from the friction from braking is not captured or put to use.
With regenerative brakes, the braking system captures that kinetic energy and transfers it into the car’s batteries, thus wasting less energy than it would with friction braking. It's estimated that most hybrids capture up to 90 percent of energy normally lost through heat during braking and use it to recharge the battery through electrical motor resistance, thus helping to preserve and replenish range in an electric or plug-in hybrid vehicle.
In a conventional hybrid, the recovered energy from regenerative braking helps power some auxiliary functions in the car, such as the audio and climate control systems. This takes some of the load off the engine and electrical system and improves efficiency.
How Regenerative Brakes Work
Regenerative brakes work by reversing electric motors that propel a vehicle. It works like a generator and feeds energy back into the hybrid or electric system to help replenish a little bit of range. These small boosts in battery range can accumulate and improve efficiency over time when used regularly.
Drivers can activate regenerative brakes in a few different ways. Some hybrid and electric cars have a paddle by the steering wheel that activates the regenerative brakes. However, activation is seamless in most cars with regenerative braking. Applying the regular brake pedal with your foot makes the regenerative and friction brakes work together to slow down the vehicle. Some vehicle systems can use regenerative brakes when the car is coasting. Sometimes called one-pedal driving, drivers may use the feature while in a specific drive mode that emphasizes efficiency on longer trips.
Although regenerative brakes are entirely different than friction brakes, it achieves the same goal of slowing down and stopping a moving car. Since it has the same effect as regular brakes, the brake lights still come on when using regenerative brakes as a safety measure – meaning when you lift your foot off the accelerator, the regenerative brakes activate automatically and the brake lights on the back of the car turn on like they would if you were to depress the brake pedal.
Recovered energy: Hydraulic brakes waste energy by turning kinetic energy into heat. However, regenerative braking feeds that energy into the car’s batteries and turns it into a little extra driving range.
Improved range: Regenerative braking doesn’t add significant miles to your driving range. Still, those gains in recaptured energy can really add up when used liberally and regularly. Hybrid and EV drivers know that every mile of battery range counts.
Reduced brake wear: The more you use regenerative brakes, the less you need to use traditional friction brakes. That means fewer trips to a service center for brake pads, rotors, and shoes. With regenerative braking, some hybrids and EVs can go around 100,000 miles between brake services.
Takes getting used to: Regenerative brakes take a little getting used to, especially if you’re shopping for a used example of an early EV or hybrid. This technology is advancing, but regenerative braking sometimes can feel weird to certain drivers, which can be jarring at first.
Less reliable at high speeds: Friction braking is a very old technology that is very reliable. When you slam on the brakes in a car with hydraulic disc or drum brakes, the vehicle reliably comes to a stop promptly. Regenerative brakes aren’t as good as friction brakes for emergencies where the car has to quickly come to a complete stop. That’s why hybrids and EVs typically use both types of braking systems.
Low speed, low benefit: When you use regenerative braking in low-speed city driving, it doesn’t generate enough energy to make any meaningful impact on the range of your car. For that reason, using regenerative brakes in low-speed driving has little benefit.
Brake and Regenerate
As mentioned, regenerative brakes are a great way to preserve the range of an EV and improve the efficiency of a hybrid. You can use them to recapture a lot of energy, or you can let them work in the background without changing your driving habits. Either way, you’ll be glad your next hybrid or EV has them!
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