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Best way to accelerate from a stop?

Discussion in 'Gen 2 Prius Fuel Economy' started by dprice23, Jun 9, 2007.

  1. dprice23

    dprice23 D-Man

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    I read in the P & G article by Wayne Gerdes over at cleanmpg.com that during pulse you should see arrows going from the ICE to the wheels and through the MGSet to the battery pack, with no assist from the battery:



    [attachmentid=8717]



    But if you accelerate from a complete stop that way it will be VERY slow acceleration, not much faster than EV only. I'm finding that if I accelerate with assist from the MGSet but not drawing from the pack at first (arrows going from the ICE and the MGSet to the wheels, no arrows going to the battery pack), I can get up to speed a little more reasonably and then fairly quickly back off to the "proper pulse" screen.



    Anyone else have any thoughts on this? I'd really appreciate some input on how best to accelerate from a stop for max FE.
     

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  2. ken1784

    ken1784 SuperMID designer

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  3. JimboK

    JimboK One owner, low mileage

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    I think you're correct -- for that initial burst of acceleration, you'll probably find it hard to avoid pulling from the battery. The motor provides good and nearly instantaneous low-end torque, so with normal acceleration from a stop it wants to help. After those first few seconds after startup, with moderate acceleration it should be easy to hold the state that Wayne's article describes.



    Another rule of thumb I've proposed that seems to work for folks without added instrumentation (like Ken has): Keep MPG at or above MPH x 0.5. This should work at those startup speeds as well as higher ones. Early results from my Can-view (just a week old) suggest that if you're in the low end of this range MPG-wise, you'll be somewhat close to the 40% pedal value Ken suggests. (You other Can-view folks: Please validate or, if your experience shows otherwise, refute.) At most speeds it should also be keeping you in efficient ICE RPM ranges.
     
  4. ken1784

    ken1784 SuperMID designer

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    One thing I would like to tell...
    Safety first

    Watch your lane, signals, signs, other cars and so on, other than a display.

    Using the constant RPM method, you have to watch a display and adjust it referring the feedback all the time.
    Same as the MPH X 0.5 method...

    The constant pedal position method, maybe you'll be required some instrument at the beginning, but your can learn and remember the position by your body without any feedback later.

    BTW, you don't need any instrument.
    Just do a brisk acceleration and keep record how briskly you're and your mileage results.
    Try another brisk rate of your own, then you'll find your best mileage result of your own.

    Ken@Japan
     
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  5. diamondlarry

    diamondlarry EPA MPG #'s killer

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    <div class='quotetop'>QUOTE(JimboK @ Jun 9 2007, 01:44 PM) [snapback]458738[/snapback]</div>
    Good info Jim. I think I'll give this method a try. I can compare the FCD's mpg reading to the rpm's on the Scanguage. I have found that for pulsing(P&G) that a Throttle Position Sensor reading of 25 seems to work pretty good for keeping the rpm's below 2200.