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Regenerative braking question

Discussion in 'Gen 2 Prius Main Forum' started by yibo829, Dec 4, 2014.

  1. yibo829

    yibo829 Junior Member

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    I'm just wondering while under regenerative braking, is the car braking with only the front two wheels? And four wheel braking starts when the friction brakes engage?

    Or does the rear drum brakes always engage even though the front is braking through the electric motor?
     
    #1 yibo829, Dec 4, 2014
  2. bisco

    bisco cookie crumbler

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    regen does not use the brakes. it engages the motor generator to generate electricity. the physical brakes (front and rear) do not engage until you press down hard enough that the motor generator cannot reduce speed quickly enough. because of this, prius brakes tend to last well over 100,000 miles.
     
    #2 bisco, Dec 4, 2014
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  3. yibo829

    yibo829 Junior Member

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    So that means during regen braking only the front two wheels are braking.
     
    #3 yibo829, Dec 4, 2014
  4. bisco

    bisco cookie crumbler

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    sorry, i wasn't clear. the reduction in speed would essentially affect the front wheels, but the braking is done through the motor generator, not the brake pads.
     
    #4 bisco, Dec 4, 2014
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Hmm, I think you're right. It's front wheel drive. Except, maybe the computer applies the rear brakes some too? Our rears wore a bit faster than fronts.
     
    #5 Mendel Leisk, Dec 4, 2014
    Last edited: Dec 4, 2014
  6. magnumrtawd

    magnumrtawd Member

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    Sooooo, If on ice with light pedal pressure the anti lok brake system is inoperative?
     
    #6 magnumrtawd, Dec 4, 2014
  7. yibo829

    yibo829 Junior Member

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    That's a good question, I have not thought about that. I think when slip is detected the friction brakes come on.
     
    #7 yibo829, Dec 4, 2014
  8. bisco

    bisco cookie crumbler

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    correct.
     
    #8 bisco, Dec 4, 2014
  9. Tideland Prius

    Tideland Prius Moderator of the North
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    Well technically, none of the wheels are braking. However, because the electric motor is connected to the front wheels through the Power Split Device, then yes, the front wheels are driving the electric motor/generator to recharge the battery. See the slight difference?

    Isn't that the same as a regular car? Why would you want ABS to come on under light braking? It'll come on if detects lock-up (hence the name) so if anything, regenerative braking helps minimise the chance of locking the wheels and sliding on ice since the brake pads are not touching the discs.
     
    #9 Tideland Prius, Dec 5, 2014
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  10. Mendel Leisk

    Mendel Leisk Senior Member

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    The front wheels are braking, ie: slowing the car. Their rotation is being impeded, as usual, in this case by their connection to the electrical motor, as opposed to brake pads, but they're still braking.
     
    #10 Mendel Leisk, Dec 5, 2014
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  11. Britprius

    Britprius Senior Member

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    Only the front wheels slow the car under regen braking. If a wheel slips on the road surface regen braking is immediately canceled and normal braking takes over along with ABS and VSC.

    John (Britprius)
     
    #11 Britprius, Dec 5, 2014
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  12. magnumrtawd

    magnumrtawd Member

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    thanks john. figured you'd have good input on this.
     
    #12 magnumrtawd, Dec 5, 2014
  13. Tideland Prius

    Tideland Prius Moderator of the North
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    Fine :p
     
    #13 Tideland Prius, Dec 5, 2014
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