A larger, heavier vehicle will have more momentum, with more kinetic energy to capture — but then it will take more energy to get it moving again from a stop than a smaller vehicle would need. A regenerative system adds weight and complexity, which increases the cost. Sign up to receive Driving. A welcome email is on its way. If you don't see it, please check your junk folder. The next issue of Driving.
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How Do Electric Cars Work? A Guide to EV Basics. Some cars even have an automatic cruise control system that uses brake regeneration. This is often referred to as one-pedal driving, as you need to modulate your right foot to speed up and slow down, rather than swapping it between the brake and accelerator pedals.
In the Nissan Leaf this is referred to as the e-Pedal, and it can be switched on and off using a button on the dash. In the Kia e-Niro , there are paddles behind the steering wheel that allow four different levels of regeneration. It feels a bit more like being in a high gear and using engine braking to slow down in a petrol or diesel car. Regenerative braking usually has a detrimental effect on brake pedal feel, so it takes some getting used to - especially as you figure out the transition point between the regen braking and the hydraulic brake system.
For a run down on the best electric cars to buy now click here Skip to Content Skip to Footer. In towing situations, for instance, brake controllers can provide a means of coordinating the brakes on a trailer with the brakes on the vehicle doing the towing. Regenerative braking is implemented in conjunction with anti-lock braking systems ABS , so the regenerative braking controller is similar to an ABS controller, which monitors the rotational speed of the wheels and the difference in that speed from.
In vehicles that use these kinds of brakes, the brake controller not only monitors the speed of the wheels, but it can calculate how much torque -- rotational force -- is available to generate electricity to be fed back into the batteries. During the braking operation, the brake controller directs the electricity produced by the motor into the batteries or capacitors.
It makes sure that an optimal amount of power is received by the batteries, but also ensures that the inflow of electricity isn't more than the batteries can handle. The most important function of the brake controller, however, may be deciding whether the motor is currently capable of handling the force necessary for stopping the car.
If it isn't, the brake controller turns the job over to the friction brakes, averting possible catastrophe. In vehicles that use these types of brakes, as much as any other piece of electronics on board a hybrid or electric car, the brake controller makes the entire regenerative braking process possible. How is a hybrid vehicle different from a fully electric vehicle? Well, hybrid electric vehicles use both an electric motor and an internal combustion engine to provide a best-of-both-worlds driving experience.
They combine the driving range of an internal combustion engine with the fuel efficiency and emissions-free characteristics of an electric motor. If a hybrid is to have maximum fuel efficiency and produce as few carbon emissions as possible, it's important that the battery remain charged as long as possible. If a hybrid vehicle battery were to lose its charge, the internal combustion engine would be entirely responsible for powering the vehicle.
At that point, the vehicle is no longer acting as a hybrid but rather just another car burning fossil fuels. Automotive engineers have come up with a number of tricks to wring the maximum efficiency out of hybrids, like aerodynamic streamlining of the bodies and use of lightweight materials, but arguably, one the most important is regenerative braking.
In a hybrid setup, however, these types of brakes can provide power only to the electric motor part of the drivetrain via the vehicle's battery. The internal combustion. In part, these efficiencies are necessary due to the extreme difficulty in finding a place to recharge a hybrid. This makes longer trips difficult without relying on the hybrid's internal combustion engine, which actually cancels out some of the advantage of owning a hybrid.
An alternative regenerative braking system is being developed by the Ford Motor Company and the Eaton Corporation. With HPA, when the driver steps on the brake, the vehicle's kinetic energy is used to power a reversible pump, which sends hydraulic fluid from a low pressure accumulator a kind of storage tank inside the vehicle into a high pressure accumulator. The pressure is created by nitrogen gas in the accumulator, which is compressed as the fluid is pumped into the space the gas formerly occupied.
This slows the vehicle and helps bring it to a stop. The fluid remains under pressure in the accumulator until the driver pushes the accelerator again, at which point the pump is reversed and the pressurized fluid is used to accelerate the vehicle, effectively translating the kinetic energy that the car had before braking into the mechanical energy that helps get the vehicle back up to speed.
It's predicted that a system like this could store 80 percent of the momentum lost by a vehicle during deceleration and use it to get the vehicle moving again [source: HybridCars. This percentage represents an even more impressive gain than what is produced by current regenerative braking systems. Like electronic regenerative braking, these kinds of brakes -- HPA systems -- are best used for city driving, where stop-and-go traffic is common.
So far, HPA systems have been used primarily as proofs of concept and in demonstration projects only. They aren't quite ready for production models just yet. However, the accumulators take up a considerable amount of space, and future production plans are focused more on using the technology in larger vehicles, like vans.
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