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A question on gliding...

Discussion in 'Gen 2 Prius Fuel Economy' started by kdk84, Jun 6, 2007.

  1. kdk84

    kdk84 New Member

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    I had a question that someone can probably answer for my pretty quickly in regards to when the Prius is in "glide" mode. Is the car in fact still drawing a charge from the batter pack while you're in glide mode, just at a much much smaller rate? I have had a couple of instances on generous extended glides that my battery meter has dropped a bar during gliding (no the A/C wasn't even on).

    Not that this is a big problem or anything since even if it does draw from the battery it is obvious that it does do it at a lesser rate than when you're in EV mode. I was just curious as to whether anyone else has commented on this or has noticed this. Or perhaps it was just a fluke that happened a couple of times in my car???

    (I came up empty on the PC search)

    Thanks,

    Kurt
     
    #1 kdk84, Jun 6, 2007
  2. efusco

    efusco Moderator Emeritus
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    Yes, but it's a pretty small amount.
    I see about -6 amps on average in a 'perfect glide'.
    Comparatively when I do a glide in neutral the draw is around -2 amps (but fluctuates).

    that's why it's important, when you pulse, that it's at a rate that will recharge the battery....I use 1850rpm as my target and get about +12 amps of charging during my pulses.
     
    #2 efusco, Jun 6, 2007
  3. ken1784

    ken1784 SuperMID designer

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    We observe the HV battery current using the CAN messages.
    The Prius consumes about 1A of HV battery current when it's in READY mode but do nothing, base current.
    We saw about 3A to 7A HV battery discharge current when do gliding without any energy flow to/from the HV battery on the MFD.

    Ken@Japan
     
    #3 ken1784, Jun 6, 2007
  4. kdk84

    kdk84 New Member

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    Thanks for the info guys. I figured that there was something like this going on but I have no way of observing it in my own car.
     
    #4 kdk84, Jun 7, 2007
  5. VABeachPrius

    VABeachPrius Member

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    <div class='quotetop'>QUOTE(ken1784 @ Jun 6 2007, 11:49 PM) [snapback]457124[/snapback]</div>
    Ken / Efusco,

    I have been on the fence about buying a SGII. I drove for 62 miles and acheived 100+ mpg for that segment. I am focusing on optimizing my pulse by keeping a constant RPM (therefore the need for a SG or something similar). Will I see better results using a constant RPM value than just winging it?
     
    #5 VABeachPrius, Jun 8, 2007
  6. efusco

    efusco Moderator Emeritus
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    <div class='quotetop'>QUOTE(VABeachPrius @ Jun 8 2007, 11:12 AM) [snapback]458056[/snapback]</div>
    I really think you will...and that's knowing what kind of numbers you already get. It's certainly possible that you already have a great sense for where that optimum rpm is just inately, but I really think using that target 1850rpm has made a huge difference for me...like 10-15% improvement over my previous consistant 60mpg results.
     
    #6 efusco, Jun 8, 2007
  7. VABeachPrius

    VABeachPrius Member

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    <div class='quotetop'>QUOTE(efusco @ Jun 8 2007, 12:17 PM) [snapback]458059[/snapback]</div>
    Thank you for the reply. Is it safe to assume that properly used EV switch would benefit as well?
     
    #7 VABeachPrius, Jun 8, 2007
  8. douglas001001

    douglas001001 smug doug

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    <div class='quotetop'>QUOTE(efusco @ Jun 8 2007, 11:17 AM) [snapback]458059[/snapback]</div>
    Isn't an optimal or target rpm different than the keep it in the sweet spot techniques?

    I will admit that I don't understand 10% of hobbit's tech pages, but what I thought it was implying that it really didn't matter as long as you were in the range, more rpm in sweet spot just meant pulses were shorter.
     
    #8 douglas001001, Jun 8, 2007
  9. ken1784

    ken1784 SuperMID designer

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    <div class='quotetop'>QUOTE(VABeachPrius @ Jun 9 2007, 01:12 AM) [snapback]458056[/snapback]</div>
    I think it is sometimes difficult to keep a constant RPM.
    Japanese hypermilers are watching CAN messages which SGII doesn't show.
    They say the best pulse is achieved by 80(200max) or 40%(CANview) accelerator pedal value.

    Ken@Japan
     
    #9 ken1784, Jun 8, 2007
  10. JimboK

    JimboK One owner, low mileage

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    After seeing Ken post the 40% figure elsewhere, and after getting Can-view, I've started watching the relationship between RPM and pedal. If I hold the pedal at 40, RPM slowly increases with speed. To hold RPM steady, I have to slowly back off the pedal (which I knew anyway from the ScanGauge). Who's to say which is better. You certanly can't argue with the success of Ken and the other Japanese hypermilers! :)

    It does seem that holding the pedal constant during a higher speed pulse to, say, 40 MPH pushes RPM past my desired top end of 2300-2400. I don't think Ken and his colleagues are routinely pulsing that high, however.
     
    #10 JimboK, Jun 9, 2007
  11. ken1784

    ken1784 SuperMID designer

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    <div class='quotetop'>QUOTE(JimboK @ Jun 9 2007, 11:40 PM) [snapback]458640[/snapback]</div>
    We don't pulse to such high speed, 40 mph. We do up to 35 mph or less. :)
    http://www.cleanmpg.com/forums/articles/t-...-2006-1793.html

    Ken@Japan
     
    #11 ken1784, Jun 9, 2007
  12. FireEngineer

    FireEngineer Active Member

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    Jim,

    Since you have CanView now (#%^$@) how about comparing the ScanGauge value to CanView for us less fortunate.

    Wayne
     
    #12 FireEngineer, Jun 9, 2007
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