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Regenerative Braking question

Discussion in 'Gen 2 Prius Technical Discussion' started by nylion, Jul 4, 2006.

  1. nylion

    nylion New Member

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    I am aware that the regenerative braking is activated when you press the brake pedal or release the accelerator. However, if the traction battery is fully charged, what happens to the energy generated by the regenerative braking? Or, is the braking then turned over to the friction brakes? Anyone know how this works ?

    Thanks
     
    #1 nylion, Jul 4, 2006
  2. efusco

    efusco Moderator Emeritus
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    1)The traction battery is never "fully charged"--it will never reach 100% capacity.
    2)The car will stop or minimize regeneration as you get above approximately 72% SOC and will actually use any excess charge to force the ICE to spin to discharge the battery to more 'acceptible' levels.
    3)During active braking such as going down a long descent when the SOC reaches aroun 72% you'll notice the ICE increase in RPM and a change in the character of the braking as it switches to predominantly friction brakes. When you have the ability to watch a CAN readout you see a drop from -60 or whatever to ~ -15amps of regen at this point.
     
    #2 efusco, Jul 4, 2006
  3. tripp

    tripp Which it's a 'ybrid, ain't it?

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    You'll also notice that the car will rely almost exclusively on the battery/motors at speeds below 34 mph unless you accelerate briskly. Like evan pointed out, the car's getting rid of "excess" energy.
     
    #3 tripp, Jul 4, 2006
  4. Bill Merchant

    Bill Merchant absit invidia

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    Also, if you really mash the brake pedal hard, in a panic stop, regeneration goes out the window in the interest of stopping forward motion. Friction braking at its finest, with ABS and VSC if you have those. I just wish we could turn off auto-trans-emulation regen.
     
    #4 Bill Merchant, Jul 5, 2006
  5. qbee42

    qbee42 My other car is a boat

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    <div class='quotetop'>QUOTE(Bill Merchant @ Jul 5 2006, 03:08 AM) [snapback]281305[/snapback]</div>
    I understand why they emulate a "normal" car, but I agree with you. It would be nice to not have to search for the perfect feather position and just be able to coast when you pull your foot off the gas.

    Tom
     
    #5 qbee42, Jul 5, 2006
  6. hobbit

    hobbit Senior Member

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    Like it or not, creep force has human-kinesthetic rationale:
    http://edocket.access.gpo.gov/2003/03-12051.htm
    .
    It also takes *very little* battery power to exert creep torque
    at low speed. Barely tickles my current meter, i.e. an amp if that.
    .
    Use Neutral to get rid of it...
    .
    _H*
     
    #6 hobbit, Jul 6, 2006
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