Twenty years ago, brakes were simply brakes- you step down on the pedal and the car slows down until it comes to a complete stop. In recent years, as vehicles with hybrid, electric and battery-powered motors become increasingly popular, regenerative braking has become a topic of discussion. Well-sought after hybrid and electric vehicles like the Tesla and Prius utilize revolutionary aerodynamics, battery, and engineering technology to create a highly efficient driving experience. Regenerative braking is one of those energy-saving technologies that’s employed.
If you’re considering purchasing an electric or hybrid vehicle then you’ve probably heard the term” regenerative braking” at least a few times. What exactly is regenerative braking and what’s involved in driving a car like this?
What Is Regenerative Braking?
Regenerative braking is an energy recovery process that slows and ultimately stops a moving vehicle by converting its kinetic energy that’s created during deceleration into a form that can be used immediately or stored in the battery to power the electric motor. Regenerative braking was developed as a method to help increase the range of electric and hybrid vehicles.
A form of regenerative braking is commonly used on most of the modern vehicles constructed today. In diesel and petrol cars, regenerative braking helps charge the battery that powers ancillary systems within the vehicle which minimizes how well the engine works. However, in hybrid and electric cars, regenerative braking takes a more active role. These vehicles rely on the regenerative braking system to continually charge the battery that drives the car. Regenerative braking systems rely on a hybrid or electric vehicle, electric powered motor to convert lost kinetic energy to stored energy in the vehicle’s battery.
How Exactly Does Regenerative Braking Work?
Do you know that every time you step on your brakes loads of energy is being wasted? According to the rules of Physics, energy can’t be destroyed. Therefore, when you activate the brakes and the car comes to a stop, all that energy dissipates as heat, burns off, and is rendered useless. In a regular vehicle with a conventional braking system wasting energy is an inevitable byproduct of braking.
Automotive engineers created a regenerative braking system to help capture some of this lost energy. Regenerative braking recaptures the kinetic energy, transforms it into electricity, and uses this electricity to recharge the vehicle’s battery. In hybrid and electrical cars keeping the battery recharged is very important.
Kinetic energy is captured during deceleration. Hybrid vehicles which utilize an electric motor and a gasoline engine solely rely on regenerative braking to continually recharge the motor which is why it doesn’t need to be plugged up. In a regenerative braking system, the motor drives the wheels during acceleration but during deceleration, the wheels drive the motor. This unique interchange of energy flow helps the motor serve as a generator, repelling the rotation of the wheels thereby generating electricity to recharge the car’s battery.
Regeneration occurs when:
- The driver activates the pedal
- When the vehicle starts coasting after the driver stops pressing on the accelerator pedal
Typically, on electric and hybrid vehicles you can see this regenerative effect take place on the charging gauge.
On the other hand, electrical vehicles run off a battery charge that was plugged into a power source. Since fully electric vehicle batteries are charged at an outlet, it only uses regenerative braking to top up the battery which is why they still need to be plugged into a charging or docking station and fully charged to a hundred percent.
Conventional Braking System Vs Regenerative Braking
To fully understand how regenerative braking systems work, you’ll need to have some insight into the operation of conventional braking. While the primary purpose of conventional brakes is to stop the car, regenerative braking systems are focused on recollecting some of the energy lost during braking and converting it to energy to charge the battery.
A conventional braking system is made up of disc and drum brakes that use friction to slow down and stop the vehicle. An essential part of the braking system is the hydraulic brakes that drive it. The hydraulic brakes consist of the master cylinder filled with fluid that is connected to the slave cylinder. The brake pedal is connected to the master cylinder, when activated the piston the master cylinder pushes through the fluid through the pipes. When the fluid flows to the slave cylinders it forces the piston to apply pressure to the brakes.
The hydraulic system which is activated during braking delivers hydraulic fluid to the brake caliper pistons to slow and stop the brake disc.
While conventional braking systems employ the disc and drum brakes to produce friction and slow and stop the car, regenerative brakes are achieved by driving the motor in reverse. When the driver activates the brake, the electric motor is placed in reverse mode and the motor starts to run backward slowing down the wheels. This reverse motion is spurred by the vehicle’s momentum. This maneuver also generates electricity that charges the battery.
Electric and hybrid cars are also equipped with electric and hybrid vehicles that kick in when the regenerative system braking isn’t providing enough power to bring the vehicle to a stop. The car’s onboard computer determines when to use the traditional frictional brake system and when to put the car in reverse mode. If the driver needs to press down on the brake pedal to make a quick stop, the car will engage the traditional brakes. Regenerative brakes are ideal for stop-and-go situations.
Conventional Braking VS Regenerative Braking
Regenerative braking does have its limitations. Even the best regenerative braking systems don’t produce nearly enough stopping power as traditional brakes. Therefore, emergency stops are next to impossible with regenerative braking alone, they aren’t capable of keeping a vehicle stationary on an incline.
Regenerative brakes take a load off of the brake pads and rotors. Fewer loads mean less heat. As a result, they lose materials more slowly which means they last a lot longer.
How Effective Is Regenerative Braking?
The regenerative braking system extends the range of electric and hybrid vehicles, yet the efficiency of recovering this energy is about seventy percent. After all, according to the laws of physics no machine can ever be 100% efficient, any transfer of energy will result in some loss of heat, light, and noise. However, it can vary depending on the vehicle, the motor. It’s all dependent on driving style and how often the driver tends to brake.
It is important to note that the 70% efficiency rate doesn’t mean a seventy percent increase in driving range in an electric or hybrid vehicle. Rather 70% of the kinetic energy lost during braking can be converted into acceleration later.
What about effectiveness? The effectiveness of regenerative braking measures how your range can be increased? The effectiveness of regenerative braking is dependent upon a variety of factors including driving conditions, terrain, and of course the size of the vehicle.
Driving conditions can be a major determining factor in the range of an electric or hybrid vehicle. Driving in stop-and-go traffic, which will require you to step on your brakes more often and recapture the lost energy will increase the battery capacity more than highway driving. Terrain also comes into play because driving downhill requires increased braking periods to regulate the speed while repeatedly charging the battery. When it comes to the effectiveness of a regenerative braking system, the size of a vehicle. Yes, heavier vehicles have more momentum and kinetic energy.
One Pedaling Technique
In some hybrids and electric vehicles, the driver can determine how much regenerative braking is used by adjusting the gearshift lever while slowing the car down. Aggressive captures and store more energy but this will also result in the vehicle slowing down faster and in some instances coming to a complete stop. This driving technique is often referred to as “one pedaling”.
One pedaling. When the one pedaling technique is used, the driver navigates traffic by using only the throttle, accelerating only when they need to move ahead, releasing the pedal, and letting the regenerative braking stop the car. Instead of moving your foot between the accelerator and the brake pedal, the driver has to keep modulating the brake with their right foot when speeding up or slowing down. On the contrary, regenerative braking is always able to stop a vehicle, mainly when it’s moving at high speeds.
The entire concept of hybrid and electric vehicles is based upon their ability to decrease or eliminate fuel consumption. Hybrids tend to get better fuel efficiency when driving in city traffic. In these vehicles, regenerative brakes are key to fully charging the battery. When the brakes aren’t being activated, the battery gets low and this augments the gas engine. If the battery gets too low, it stops working in conjunction with the gas engine and instead siphons a portion of its power to help recharge the battery.
When you’re driving these vehicles, you’ll have to adjust your driving habits. Drivers will need to learn how to slow down well in advance and coast to a stop which generates more energy than slamming on the brakes.
Disadvantages and Advantages Of Regenerative Braking
Regenerative braking systems have their advantages and disadvantages. Check out this list of the top advantages of regenerative braking systems:
- It decreases the fuel consumption of the vehicle
Perhaps the main benefit of regenerative braking is that it improves fuel economy. A report published by Ford revealed that regenerative braking has saved over 100 million gallons of gas over the past 15 years.
- It helps keep the battery charged
The energy captured by regenerative brakes keeps the car’s battery recharged. The kinetic energy that would be otherwise lost the vehicle is able to experience a prolonged charge while driving.
- Prolongs the traditional braking system
Hybrid and electrical vehicles are also equipped with traditional braking systems. Regenerative braking relieves some of the load placed on friction brakes which prevents wear and tear.
The main disadvantage of regenerative braking systems include;
- Driver’s will need to change their driving patterns and habits
Driving a car with regenerative braking feels different than a vehicle with just a traditional braking system. Many claim that the brake pedals in these vehicles are soft and feel mushy. To ensure that the battery is continually charging you’ll have to use the right braking techniques so that energy is being recaptured.
- Efficiency can vary
The efficiency of a regenerative braking system in a hybrid or electric vehicle is based on ever-changing problems. The effects of regenerative braking decrease when driving at high speeds. The friction brakes will need to be activated during low speeds or when you need to make quick stops.
The Bottom Line
Yes, hybrids and electric vehicles are integrated systems that are designed to optimize efficiency, and regenerative braking is just one of those essential processes. Regenerative braking reduces kinetic energy loss, helps extend the electric range, and decreases the wear and tear of brakes and rotors. This revolutionary technology is also used in bikes and scooters.
Common Questions On Regenerative Braking
Q: What is meant by the term regenerative braking?
Regenerative braking is an energy recovery method that reduces the speed and stops a moving object by capturing and storing its kinetic energy for immediate or later use.
Q: How effective is regenerative braking?
Regenerative braking is about 60-70% efficient. However, its efficiency can vary depending on a variety of factors such as the vehicle, type of motor, size of the vehicle, driving habits and so much more.
Q: Do regenerative brakes last long?
Regenerative brakes are innovative and are manufactured to efficiently recapture energy. Therefore, you can expect regenerative brakes to last longer than traditional brakes. Some hybrid and electric vehicle owners have reported that their brakes, pads, and rotors last about 80.000 miles.
Q: Does Teslas have regenerative braking?
Yes, Tesla’s are equipped with regenerative brakes. On older Tesla models drivers have the option to change the level of regenerative braking from standard to low.