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Regenerative brake efficiency

  1. Dec 19, 2013 #1
    Is regenerative brake technology available on vehicles other than ecars and ebikes.if so what is the maximum efficiency reached till now on bikes and cars.
  2. jcsd
  3. Dec 19, 2013 #2


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    It's used in Formula 1, (called KERS, Kinetic Energy Recovery System), but it's not really meant to be that efficient. In order to comply with the rules, a computer limits the maximum energy output to 70 hp for a few seconds per lap. The braking takes place at the rear axle, and the energy is saved in capacitors as opposed to batteries, since the storage time is fairly short. I'm not sure how the excess energy beyond what the rules allow per lap is dumped.

    Mazda is also using capactors in some of it's "non-hybrid" vehicles for regenerative braking, to increase fuel economy. It also activates when going downhill as speed is moderated by the regenerative braking. It's called i-Eloop or SkyActive. Apparently the recovered energy is only used to drive the electronics in the car (and keeping the battery charged), so basically it's a "smart" capacitor / alternator system. The claim is about a 5% increase in fuel milage, not a lot, but it helps, and it's much cheaper and lighter than a true hybrid.
    Last edited: Dec 19, 2013
  4. Dec 19, 2013 #3
    What exactly do you mean by "efficiency" here? It is worthwhile to calculate the kinetic energy of your vehicle at a given speed, and then see how much fuel that represents. You will find that the majority of the fuel use goes into overcoming friction; that's why regen braking is most worthwhile for low speed frequent start & stop conditions (ie, city driving).
  5. Dec 19, 2013 #4


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    Regenerative braking is used on the Toyota Prius, and I believe on most other hybrid vehicles. It is one of the reasons that hybrid vehicles have better fuel economy.
  6. Dec 20, 2013 #5
    By efficiency i mean energy lost to energy recovered.
    And is there any technology to recover it in conventional vehicles.
  7. Dec 26, 2013 #6
    The driver is responsible for more losses than the technology.
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