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Regen braking CC vs no Cruise

Discussion in 'Gen 2 Prius Technical Discussion' started by efusco, Jul 3, 2006.

  1. efusco

    efusco Moderator Emeritus
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    Ok, very vague observation that I haven't formally tested, but I thought maybe others with CAN data accession tools would want to take a look and see if they can confirm or rebut.



    I've noticed, on CAN-View, that I seem to be able to get good maximal regen when I begin braking when NOT using CC or when I first deactivate CC before initializing braking. But if I'm in CC and don't deactivate it first I seem to be able to only get -15 amps or so of regen unless I lift my foot totally off of the brake pedal for a moment then reapply.



    I may simply be braking too briskly in the CC cases, but I don't think so.



    Anyway, this is something new to look at and test for those of you bored and loney on this holiday!
     
  2. tumbleweed

    tumbleweed Senior Member

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    <div class='quotetop'>QUOTE(efusco @ Jul 3 2006, 06:52 AM) [snapback]280480[/snapback]</div>
    I don't have CAN-View but your post brings up a question. What actually did you mean? I know you realize that as soon as you apply the brakes the CC goes off, are you saying that if you have CC set to some speed and turn it off with the brake pedal you do not regen as much as if it were turned off with the CC switch? How can that be, if it's off it's off?
     
  3. efusco

    efusco Moderator Emeritus
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    <div class='quotetop'>QUOTE(tumbleweed @ Jul 3 2006, 10:58 AM) [snapback]280520[/snapback]</div>


    Well, I agree that it doesn't make much sense, unless the rate/force of braking required to turn off CC is beyond the threshold for maximal regen. braking. That's why I want someone else to confirm this very preliminary observation.
     
  4. Frank Hudon

    Frank Hudon Senior Member

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    time to inteact with one of you children, Evan, what I want you to do is have them watch the brake lights and you with the car powered on slowly press on the brake pedal and have them tell you when the lights come on. I'm starting to think that your brake switch might be slightly mis-adjusted. The brake light should come on with 1/2" to 3/4" of pedal travel. It might just be possible that the stroke simmulator is getting the wrong signal. CC on and no brake lights yet so it tells the computer to limit the regen. Just a thought
     
  5. KMO

    KMO Senior Member

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    Here's another thing about CC and regen for people with a CAN-View to look at.

    I occasionally read messages from people suggesting that the cruise control should regen to maintain the speed downhill. But I believe it already does, albeit not by much. But I may be imagining things.

    Can someone with the CAN-View confirm or deny this? Compare regen current when going down a hill with the CC set and drifting above the desired speed, to that with the CC off and foot off the pedal.
     
  6. hobbit

    hobbit Senior Member

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    The CC is not *necessarily* dropped by the stoplight switch going
    on. It could be a changing voltage from the stroke sensor, or
    [less likely] pressure increase at the master cylinder.
    .
    I do know that the brake ECU is triggered into an active state when
    the car isn't in READY mode by stroke sensor input [the pot that
    watches pedal-pivot swing]. Not the stoplight switch. I noticed
    this because I had the switch disconnected but I could still hear
    that soft whining of the solenoid drivers start up when I moved the
    pedal a little. By moving just the little arm that connects the pot
    to the pedal I could trigger the same response too.
    .
    _H*
     
  7. Frank Hudon

    Frank Hudon Senior Member

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    CC is stopped by a signal from the brake lights coming on. Easy test put a momentary contact PB switch across the brake light switch and set CC driving down the road. Press the PB sw and your out of CC. NTSA wouldn't allow it not to drop CC. Not powered on is probably a different set of signals to the various computers than when it's in Ready.