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HSI "CHG" bar and regen/friction braking?

Discussion in 'Gen 3 Prius Main Forum' started by iansgp, Jul 26, 2010.

  1. iansgp

    iansgp Gen3 and Gen4-plugin owner

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    Prius III -- I do all in-town driving with display in HSI mode. When braking, I have naively assumed that the length of the CHG bar corresponds with regen braking capacity -- fill the bar and you're starting to add friction brake. So when stopping distances permit, I try to brake gradually enough to keep a bit of space past the end of the CHG bar -- means I'm playing with brake pressure the whole length of a typical freeway exit ramp.

    Is this a valid interpretation of the display? Short of investing in a scangauge, is there a better way to manage braking to keep it 100% regen down to 7 mph?
     
    #1 iansgp, Jul 26, 2010
  2. GrumpyCabbie

    GrumpyCabbie Senior Member

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    There are some previous posts on this subject and one of the latest gives a graph showing how regen and friction combine.

    You're not too far away from the mark in your assumption but there is always some friction braking with regen, but the graph (which I wish I could find) from the earlier thread shows how this works. It isn't quite as simple as a merge from one to the other, but not far off.

    I'm sure someone out there will post this graph or a link to it.
     
    #2 GrumpyCabbie, Jul 26, 2010
  3. tumbleweed

    tumbleweed Senior Member

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    Yes that is valid, however as speed decreases to below 20 MPH or so friction braking gradually takes over and by the time you are down to 2 or 3 MPH there is no more regen. If you almost completely fill the regen bar you can regenerate 70 or 80 Amps. I too modulate braking to keep friction brakes from working, unless I really need them of course.

    Check out this from our Prius friend Hobbit: http://techno-fandom.org/~hobbit/cars/HSI/

    It might be what Grumpy was thinking of.
     
    #3 tumbleweed, Jul 26, 2010
    2 people like this.
  4. GrumpyCabbie

    GrumpyCabbie Senior Member

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    It wasn't but it's very interesting none the less.
     
    #4 GrumpyCabbie, Jul 26, 2010
  5. ksstathead

    ksstathead Active Member

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    #5 ksstathead, Jul 26, 2010
  6. iansgp

    iansgp Gen3 and Gen4-plugin owner

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    Thanks, all! Hobbit's Tao of HSI ought to be mandatory reading for any newbie... glad I got pointed to it.
     
    #6 iansgp, Jul 26, 2010
  7. GrumpyCabbie

    GrumpyCabbie Senior Member

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    #7 GrumpyCabbie, Jul 26, 2010
  8. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    Seat of the pants observations...

    Pre-recall: I think this was entirely valid for early 2010 vehicles (produced early-mid 2009)
    Post-recall: I feel there is a bit of friction braking along w/ the charging so that if regen "lets go" during an ABS situation, the car isn't free-wheeling for 8/10th of a second before friction braking kicks in.
     
    #8 HTMLSpinnr, Jul 27, 2010
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