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Driving in "B" Mode Regularly

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

  1. alexcue

    alexcue Active Member

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    I obviously didn't understand your question then. Why would a non-hybrid downshift in city driving? I see no reason why a non-hybrid would. But the B as we have been discussing, is for a Hybrid.
     
  2. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    Sorry :(. I somehow thought that the discussion involved B mode with both hybrids and non-hybrids.
     
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  3. fuzzy1

    fuzzy1 Senior Member

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    Why not? Or, when did such methods become disapproved? We have downhills with stop signs and stoplights at the bottom. Why approach hot?
     
  4. alexcue

    alexcue Active Member

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    I'm not disagreeing with you, that's when you WOULD use a lower gear in an automatic. On the flats, a non hybrid would not see a benefit of using it IMO.
     
  5. Trollbait

    Trollbait It's a D&D thing

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    Driving in the lower gear on city streets can limit the gear hunting and shifting that some don't like, and also wastes energy.
    Our Sable has OD, D, 2, and 1. The manual says to use D for that reason, and the car is old enough that selecting a lower gear will lock it out of use. Newer automatics could change the shift points with a lower 'gear' selection, but still allow access to the higher gears.

    Plus, limiting brake use has the same benefit of extending brake life in all cars, not just hybrids.
     
  6. giora

    giora Senior Member

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    Yes, it's easy to confuse regeneration rate with efficiency. I did the same back in 2013 when being new to the PiP, seeing those estimate numbers accumulate faster feels good. Even these days I have to remind myself from time to time that regeneration is only about 50% efficient.
    Toyota was advocating all along that when it comes to regeneration - less is better.
     
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  7. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    Although when discussing hybrids, one has to take care to be very clear when using the term "brake use" as to whether one is talking about "applying brake pedal" or "using friction brakes". On those primitive non-hybrids, there is no confusion. :)
     
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  8. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    As Newbie to Prius World I found it equally difficult to glide either in "D" or "B" mode while in E/V.
    One observation:
    My 'gliding' attempts increased my e/v range from 31 to 35 miles on my flat daily commute in "B" mode.
    Strangely while in "D" mode I could not achieve such e/v range gains with my 'gliding' attempts (max was 32-33 miles e/v range).

    Maybe my D-gliding requires more skills (less acc pedal travel to eliminate re-gen?) or/and does re-gen works differently in B in comparison to D mode?

    Here come my questions:
    is the Prime re-gen efficiency speed dependent aka kinetic energy/load of generator)?
    on in other words:
    In scenario of slowing down to complete STOP is combination of 'gliding' + stronger re-gen driving technique better than just applying continuous slight re-gen all the way to STOP?
     
  9. stevepea

    stevepea Senior Member

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    I tried both, and personally also found the same -- that gliding using B (in EV-Mode) increased the EV range gain more than D+Brakes (and have continued to use it as default and occasionally switch to compare) -- especially true if you're heading for stops all the time rather than just letting up on the gas so you don't go too fast. Remember too, that when in B, if you don't want such a quicker stop, you can find the sweet spot with your pedal and keep it on just a tad (to mimic D). Also, regardless of if you use B or D+more brakes, the gentler your starts are, the more range you'll have left.

    I can also suggest (if it doesn't distract you), that besides looking at the "EV Range left" numbers, you put your two displays as follows:

    For the main display, put it to the screen that shows both the accel and regen level graphs (the one that also shows your ECO score). That way you can see firsthand by looking at the real-time graph the amount of regen the car is actually getting, and can compare between B and D+brake.

    For the smaller changeable display just to the left of the main display: set it to "miles per kw/h" to show you in real time the efficiency of what you're doing (when in HV Mode this setting shows MPG, when in EV Mode, this setting shows "miles per kw/h"). If you're curious you can switch back and forth between B and D when driving at the same speed and you can see there is no change in the meter. Likewise, it's generally the equivalent of an MPG meter for EV Mode, so you can use it to help see how efficient your starts are, how much the load on the battery is, etc.
     
    #109 stevepea, Jun 7, 2017
    Last edited: Jun 7, 2017
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  10. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    That sounds like a recipe for horrible mpg, lol.

    I've tried valiantly, on a few occasions, to hypermile our daughter's Pilot, fwiw.
     
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  11. Tideland Prius

    Tideland Prius Moderator of the North
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    Just pulse & coast in a regular car.

    2002 Camry 2.5L 4 cylinder, 4A:

    Regular driving: 10.9L/100km (21.5mpg)
    Pulse & coast: 8.5L/100km (27.7 mpg)

    All according to the onboard trip computer. Sure, it's not like the 50 mpg that Wayne got out of a 4 cylinder Accord but hey, it's a noticeable improvement.
     
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  12. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    I also found that. actually 'gliding' in E/V "B" mode gives more control over re-gen/ speed and reduces significantly the need for friction breaks in normal driving conditions.
     
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  13. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I shift into "N" and the problem is solved. But I only use "N" primarily in the neighborhood to reach the cross town streets or when exiting to an access road in low traffic conditions. Otherwise, I'm either in "D", normal traffic with dynamic cruise control, or "B" during our infamous Huntsville rush minute or construction zone. I preferred a laid back driving pattern.

    Bob Wilson
     
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  14. Trollbait

    Trollbait It's a D&D thing

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    Well, in hybrid mode, B gear is also throwing away more energy than D for the Prime and Prius.
    When trying, I can get our Sable with the 3L V6 to push 29mpg; calculated from a fill, we don't got fancy displays on that car. The trying actually isn't trying, and the fuel economy was still decent when I left the car in D and not OD on country roads once.
     
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  15. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    Thanks Bob - That exactly what I do.
    BTW
    Tried using "N", but turned out that the 'gliding' worked better
     
  16. giora

    giora Senior Member

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    For efficiency - gliding is better than coasting, coasting is better than brake regen.
    In the scenario you are describing I would say the best will be to start react to the situation as early as traffic permits.
     
    #116 giora, Jun 7, 2017
    Last edited: Jun 7, 2017
  17. Lee Jay

    Lee Jay Senior Member

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    How are gliding and coasting different? They're both zero torque applied to the wheels.
     
  18. Tideland Prius

    Tideland Prius Moderator of the North
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    Gliding = freewheeling. No power going to the wheels. No regen. (i.e. lightly pressing on the accelerator)

    Coasting = Car is regen-ing but no pedals are applied. (Car is regen via "foot-off-the-accelerator")
     
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  19. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    The Prius simulates the engine drag that you get in a conventional ICE car when the foot is off the accelerator by doing regeneration. Difference is, in a conventional car, this is wasted energy, but in the Prius, a certain percentage (50%?) is reclaimed.
     
  20. Lee Jay

    Lee Jay Senior Member

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    Okay, well, those terms make no sense to me. Some "coast' definitions:

    "to continue to move or advance after effort has ceased; keep going on acquired momentum: "

    "(of a person or vehicle) move easily without using power."

    Regen is both "effort" and "power", so it's not "coasting".

    By the way, as an R/C glider pilot, I would say the same about "gliding" - no effort, the same as "coasting".