B mode: What is the advantage to use B mode when driving, more regeneration? more economy?

Discussion in 'Prime Technical Discussion' started by Gaëtan Lafrance, Jul 5, 2018.

  1. breakfast

    breakfast Active Member

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    If a Prime driver wants some of the same feeling (not having to tap their brakes) in stop and go traffic, with the benefit of brake lights lighting up during times of regen, they could use their dynamic radar cruise control...
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah maybe just your sugar levels dropping. :)
     
  3. sam spade 2

    sam spade 2 Senior Member

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    YOu misunderstand.

    The brake lights still work like "normal" when you actually push the brake pedal.

    They do NOT come on when you do NOT push the pedal......when the car is slowing down ONLY from additional regen or engine compression braking due to using the B mode.
     
  4. fuzzy1

    fuzzy1 Senior Member

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    Do you also believe that it should be illegal that brake lights don't come when you downshift any or all other transmissions, manual or automatic? B mode is effectively the same thing.
    B mode won't make a sudden stop, period. You need to stomp on the actual brake pedal to make such a stop.
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    I guess we beat that one to death, lol.
     
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  6. Starship16

    Starship16 Senior Member

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    Sorry, guys. I misunderstood schja01. Thanks for clearing that up! I just want to simply drive this car, and not have to think about it so dang much! :LOL: Too much reading of Priuschat, probably. In some cases, a rookie/newbie might feel overwhelmed with all this information (many times conflicting information.) But it's a great website, and keep up the good work.

    People just need to read the 800 page Owner's Manual! :eek::ROFLMAO:

    Back to my cookies & ice cream.
     
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  7. Starship16

    Starship16 Senior Member

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    My granddaughter says... "Papa, what's all that weird stuff on those screens???"

    Just forget it dear, and go back to your iPod.
     
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  8. Pdog808

    Pdog808 Active Member

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    I got that information from this posting:

    Regenerative vs. Friction Braking | PriusChat

    I'd have to use Scangauge myself to verify but I have no reason to doubt @Kramah313 .

    When you are in "B" mode AND in EV, you are enabling a more aggressive regen curve which causes the car to slow down much more quickly when the gas is let up OR the brakes are engaged.

    I worked on a project involving a large prototype vehicle using CNG (Compressed Natural Gas) and electric motors. At the time, there wasn't very effective inverter technology and a battery pack capable of taking a regen charge quickly. We would dissipate regen energy as heat through a network of resistors on the roof. Whenever we would change the regen curve on the brakes, it would greatly affect braking performance on the vehicle (think "D" versus "B" modes).

    After a year of testing, you couldn't even tell if the huge disc brakes were used at all.
     
  9. Kramah313

    Kramah313 Active Member

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    I will offer the caveat that I found that information to be true in my gen 3 2012 non-plug in version. I’m not sure if the prime works the same way, but it wouldn’t be surprised if it did, especially in HV mode.
     
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  10. jerrymildred

    jerrymildred Senior Member

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    I'm not sure yet that we totally understand each other yet, @Pdog808 and @Kramah313. If I understand you right, if the regen indicator (CHG on the HSI) is, for example, at 50% of its travel in B mode, there is more current going back to the battery (and greater deceleration) than if it showed 50% in D mode using the brake pedal? In other words, as I understand it, they are remapping the CHG indicator. This would need to be the case for what I think you're saying if indeed B mode will decelerate more strongly than regular braking without using friction.

    My observation is the opposite. Whether I press the brakes to decelerate or use B mode, I get the same indication on the HSI for the same perceived deceleration. I'll have to hook up my phone to the car and get some numbers now.
     
  11. Kramah313

    Kramah313 Active Member

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    For the gen 3 I’ve found with B mode that when you coast it just goes farther to the left then it normally would. I think the CHG mapping is the same. So normally costing is like -10 amps from the battery, whereas it might be -20 or -25 in B mode. There’s some other stuff that happens at high speed in B in the regular Prius I have never experienced. Like the engine turning on with no fuel injected to slow down the car.

    That being said, I never really meant that post to be about about B mode and have only used it once or twice in my Prius since it’s not a plug in.
     
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  12. sam spade 2

    sam spade 2 Senior Member

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    Yes that can be bad for your (mental) health !!! :ROFLMAO:
     
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  13. Pdog808

    Pdog808 Active Member

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    What I've found is that in "B" mode, the CHG indicator seems to take quite a bit more deceleration via braking before pegging to the far left. It's possible that "B" mode may increase charge rate back into the batteries in a non-linear manner the closer you get to actually using the brake pads. (Although I still believe it's a linear coefficient that is applied to the deceleration/CHG curve but have no data to back that up.)
     
  14. Starship16

    Starship16 Senior Member

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    This long thread reminds me, I gotta go check my brake lights.
     
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  15. jerrymildred

    jerrymildred Senior Member

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    :LOL: Oh, we're just getting started! LOL!! :ROFLMAO:

    Edit to add: How do you think we get such high post counts? :whistle:
     
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  16. stevepea

    stevepea Senior Member

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    Kind of like those old "Burma Shave" billboards at the side of the road, where you'd pass by a series of them, one after another?

    Look, doing the "B" thing isn't for everyone. Some people just want to drive the Prime no differently than as if it were a Buick. That's fine. But the OP asked the quesiton, and for those willing to do some extra work to squeeze every inch out of the EV range (from monitoring your speeds, to figuring out when you want to deploy EV vs HV, to switching to B and then back to D again when the EV range runs out) there are things you can do if you don't mind doing the extra work.

    Or you can just switch the Prime from ECO to POWER (in EV), step on the pedal, and have a lot of fun for a few short minutes...
     
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  17. Mendel Leisk

    Mendel Leisk Senior Member

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    We were walking the dog last night, around 10 PM, and I swear every second car going by had both license plate lights burnt out. There's zero roadworthiness inspections up here, we apparently don't need that stuff anymore.

    Saw a couple of cars pass by with their back ends completely dark, not sure if they're brain-dead, or it's an electrical short, or (most likely): they're driving with just their daytime running lights. The latter's hard to comprehend too: how the heck would they miss that their dash is black??
     
  18. stevepea

    stevepea Senior Member

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    When I was in Iceland, I remember about one in every 8 oncoming cars seemed to have one of its two front headlights out, almost seemed like a virus infecting the cars there. Not the best idea in a place that can have some bad weather.

    Well, I'm willing to do a lot to stretch that EV range, but turning off the DRL is not one of them. I have the Plus so it's not automatic, but for safety, I always make sure to use my DRL whenever I drive, regardless of the time of day. After all, what good is that extra 1c of electricity saved if you're not around to enjoy it?
     
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  19. Mendel Leisk

    Mendel Leisk Senior Member

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    DRL's are a bit different up here: when neither parking lights or head lights are selected and the car has been shifted out of Park, then DRL's are on, no choice about it, and no other trim lights. With our 3rd gen the DRL's are the high beams at half-brightness. Not sure how it's implemented in fourth gen but would be similar.
     
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  20. sam spade 2

    sam spade 2 Senior Member

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    Most other cars "down here" are like that too.
     
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