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Driving in "B" Mode Regularly

Discussion in 'Prime Main Forum (2017-2022)' started by stevepea, May 25, 2017.

  1. Tideland Prius

    Tideland Prius Moderator of the North
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    Coasting has been used in the automotive lingo way before the Prius. As early Prius members, we were deciding what to call the freewheeling mode. Some have used "stealth" (but might be confused with EV mode). Glide was chosen because it was essentially like shifting into neutral on a regular car - like a cyclist or like a plane.


    Isn't the English language fun? :)

    You mean the electric motor? The engine only comes on after a certain speed to reduce pumping losses and to prevent overspinning of MG1.
     
  2. stevepea

    stevepea Senior Member

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    RE: Gliding vs Coasting.
    Wow, didn't realize there was a difference; I've kind of used them interchangeably. To avoid confusion, I'll say that in my posts where I have talked about "gliding" I meant where one simply takes the foot off the accelerator pedal (which might be considered "coasting", then?)

    The difference between gliding and coasting. You know, it just makes me continuously -- I mean continually -- ah #%&()@# :)

    And as they sometimes still say on TV news promos... "film at 11!
     
  3. giora

    giora Senior Member

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    I would like to be clear here:
    Gliding (prius chat gliding, freewheeling) from point A speed 1 to point B speed 2 is more efficient than coasting (PC coasting) from point A speed 1 to point C speed 3 and then picking-up speed to reach point B at speed 2.
    Same goes when comparing coasting to braking plus accelerating.
     
  4. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    I wish these definitions should be put in some sticky post - just for clarity of forum language.
    BTW In my posts I used exact same definition of those terms

    Kris
     
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  5. Lee Jay

    Lee Jay Senior Member

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    On a bicycle, zero pedaling and zero braking is called coasting, not gliding.
     
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  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Stickied in the Newbie forum :)

    PriusChat Glossary | PriusChat
     
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  7. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Just send them to a place where such terms are an important part of their heuristic.

    I'm a follower of @john1701a,"Just drive the car."

    Bob Wilson
     
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  8. giora

    giora Senior Member

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    On a plane, coasting i.e. landing is different from gliding as while coasting you are intentionally increasing resistance to movement over the resistance while gliding.
    Anyways, if you think of better terms to describe those two phenomena in hybrid and EV cars and braking is already in use for a third operation, please suggest.
     
    #128 giora, Jun 8, 2017
    Last edited: Jun 8, 2017
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  9. Prodigyplace

    Prodigyplace Senior Member

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  10. Lee Jay

    Lee Jay Senior Member

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    Zero torque = coasting.
    Simulation of natural engine braking = light regeneration.
    Simulation of shifting down (B-mode) = strong regeneration.
     
  11. Trollbait

    Trollbait It's a D&D thing

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    The terms are used outside of Priuschat and hybrids by hypermilers of any car. The pulse and coast technique of hypermiling has been described as early as the '40s or '50s in an article on efficient driving from Popular Science or Mechanics.

    Coasting is letting the car roll in gear without engine input.
    Gliding started with hybrids, and possibly with BEVs of the EV1 era, to describe coasting with no regen braking applied. It has since moved on to describe any coasting in which engine and transmission drag has been minimized, like coasting in neutral.
     
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  12. Lee Jay

    Lee Jay Senior Member

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    So why is it called "pulse and glide"?

    Then there would be no engine drag.

    Do you see a problem describing "gliding" as "coasting" as a means to distinguish it from "coasting"?

    "Coasting" in a bicycle is a common term for no pedaling and no drag outside of parasitic drag (rolling friction and aero drag).
     
  13. Trollbait

    Trollbait It's a D&D thing

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    To distinguish it from coasting in gear.

    Do I have lice?

    Not when discussing fuel efficient driving within the hypermiling community.

    When talking about riding a bicycle, I wouldn't be using the term glide.

    These terms were defined among sites like Cleanmpg and Ecomodder. If you feel these terms don't fit as defined, you need to change people's minds there. I personally think warp stealth is a horrible term that I first saw here for using the minimum amount of motor input to maintain highway speeds, but not enough to try to change it.
     
  14. giora

    giora Senior Member

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    If shifting to "N" at certain situations and to "B" at others is "Just drive the car" then all of us just drive it, even "Pulse & Glide" is.

    Back to subject:
    With Toyota plug-ins, releasing the go pedal while in 'B' is equivalent to 'D'+brake with same efficiency, so in my perception it is braking and not coasting.
    In city driving (and other) there are quite few situations where all that is needed is coasting (D and no pedal or light regen), driving in B position may perform less efficiently in these situations, i.e may require picking-up speed. That is why, in long terms, driving in B position is less efficient than in D position IMO.
     
  15. Trollbait

    Trollbait It's a D&D thing

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    Because of the lice, all coasting is braking.
    That depends on how easy it is for a particular driver to control gliding and accelerator regen braking.
     
  16. giora

    giora Senior Member

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    What is lice? do you mean ICE? we are talking of EV driving here.
     
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  17. Trollbait

    Trollbait It's a D&D thing

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    Lice as in the bug, and nit picking.;)
     
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  18. giora

    giora Senior Member

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    Rolling dice?:rolleyes:
     
    #138 giora, Jun 9, 2017
    Last edited: Jun 9, 2017
  19. giora

    giora Senior Member

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    If by 'that' you mean the degree of efficiency loss - then yes.
     
  20. GT4Prius

    GT4Prius Active Member

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    Ok apologies coming in late to this discussing and haven't read all latest posts as some getting repetitive. I myself am going to repeat a point that has already been made though.

    lf the EV battery is fully charged, B mode CANNOT use regen to slow the car and MUST start the ICE. Even in EV mode. Otherwise there's nowhere for the regenerated energy to go. That is very very inefficient and wasteful.

    Also, regenerating energy is a lot less than 100% efficient, so thinking ahead and letting the car roll with its own kinetic energy is more efficient than slowing down with regen and then speeding up again, which is what B mode will encourage. Laws of physics.

    Finally, Toyota want to have the best commercial advantage by programming the car to work as efficiently as possible. If B mode achieved this, would it not be the default?

    I have the car by the way! I have not yet used B mode and recently my EV range predicted went over 40 miles.

    Posted via the PriusChat mobile app.
     
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