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Driving in “B” mode while making deliveries in town

Discussion in 'Gen 3 Prius Main Forum' started by Skackdaddy, Nov 9, 2019.

  1. Skackdaddy

    Skackdaddy New Member

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    Can i leave my 2010 Prius in “B” mode while making stop and go delivery in town
     
  2. bisco

    bisco cookie crumbler

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  3. Grit

    Grit Senior Member

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    Wait for low mpgs follow up post.
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Nah, let's just tip toe away. :sneaky:
     
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  5. meeder

    meeder Active Member

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    Why would you want to do that?
     
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  6. Skackdaddy

    Skackdaddy New Member

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    Help save the brake pads
     
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  7. Mendel Leisk

    Mendel Leisk Senior Member

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    I would save B for long downhills, long enough that the hybrid battery will fully charge and you've still got a long ways to the bottom. It's main purpose is to reduce the risk of overheating friction brakes. They normally play second fiddle to the regen braking, have an easy time. Except in scenarios where the hybrid battery is so full that the car falls back to friction-brakes only.

    In normal conditions, it will effectively reduce the amount of charging, and your mpg. It's a bit different than a high gear lock-out or sport-mode on a traditional automatic.

    Around town, when you need to slow or stop, just using the brake is the best ploy.
     
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Should add: the way B works, reduces the load on the friction brakes, is by employing engine braking, which you can hear, the high revving, particularly during deceleration, and even more as you start using the brakes.
     
  9. Grit

    Grit Senior Member

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    What if the OP lives in hilly areas? In SF city limits, I regen up to 80% at places as the hv fan is at speed 6 constantly.
     
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  10. Mendel Leisk

    Mendel Leisk Senior Member

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    But short hills, and up as much as down?

    Do you max-out hybrid battery charge?
     
  11. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Burn extra gas to spend less on brake pads.

    Makes sense to me, when a brake job is a few thousand bucks.

    Except they aren’t… usually.
     
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  12. potatoesLOL

    potatoesLOL Active Member

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    I literally drive everywhere in B mode... after installing an exhaust :ROFLMAO:
     
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  13. Pluggo

    Pluggo Senior Member

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    B mode is totally appropriate for city driving because it reduces the required reaction time when driving stop and go in tight traffic. During that interval between lifting your foot and deciding to brake, B mode makes that decision for you and the answer is always 'instant braking.'
     
  14. jerrymildred

    jerrymildred Senior Member

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    Even in a 2010? If I'm not mistaken, that would use the engine for an air brake. Not at all like a PiP or Prime in EV mode.

    Also, as soon as you lift your foot from the "go pedal" regeneration begins; just not as strongly as in B mode when driving EV. In either case, the friction braking doesn't come into play before the last 4-7 mph unless it's a hard stop.


    @Skackdaddy, it won't hurt to use B, but it won't do much to save your brake pads. It will burn more gas. If Gen 2 brakes are typically lasting 150,000 or more miles, Gen 3 should not be any worse. As long as you're not waiting till the last moment to slam on your brakes like most race car drivers. ;)
     
  15. Raytheeagle

    Raytheeagle Senior Member

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    OP lives in Palm Springs;).

    Slightly hilly on the edges of town, but not San Fran hilly(y).
     
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  16. ChapmanF

    ChapmanF Senior Member

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    Just a couple points for the "keep it as simple as possible but no simpler" angle ...

    B mode won't always use engine braking, any more than D mode will. It's a matter of changing some setpoints. B mode sets the 'foot off gas' regeneration torque to be a little higher than under D mode; it also sets the battery charging rate limit to be a little lower. When the regenerated power exceeds the charging limit, the rest goes to the engine, so B mode makes that more likely but not inevitable. If the battery has capacity available and the regen power doesn't exceed the limit, there's still no need to engine brake.

    It's not quite the case that the friction brakes are out of the game except at the lowest speeds or under hard braking. There's a more complicated relationship involving speed, power, and braking demand. They can be used some early in a brake request, then tapered off, then brought back in as the car is closer to stopping. It's all programmed in to the ECUs so it doesn't depend on us knowing all the details to drive the car, which is good because there really isn't any simple saying to memorize that would capture it.

    ... other than "it does what it does." That's not too hard to remember. :)

    [​IMG]
     
  17. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Now why couldn’t they have made a live graph like ^ that on the dashboard?
     
  18. Mendel Leisk

    Mendel Leisk Senior Member

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    When the car's sat a few days after washing, and the brake rotors have had a chance to rust up, I can really hear the friction brakes for the first block or two, every time I push the pedal. Hearing that I reason it's not all-or-nothing, braking is a mix of friction brakes and regen.
     
  19. ChapmanF

    ChapmanF Senior Member

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    By the time you'd figured out what you were being shown, you'd have clipped a milk truck, a stop sign and a tree, and come to rest in a ditch.
     
  20. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Fair enough. As it is we set it on the big clock/fuel remaining screen about 2 days after we bought it. (and left it that way)