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The useage of B mode

Discussion in 'Gen 3 Prius Main Forum' started by LulzChicken, Aug 6, 2009.

  1. LulzChicken

    LulzChicken Prius Enthusiast

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    Hey guys, I have a quick question. I normally use B mode when I start to break at a red light or anything like that to help in not using my actual breaks so much and to slow down quicker. Is this going to cause any wear on my parts or make anything wear out quicker than it should? All I do is switch to B mode, break, and then put it back in drive. I doubt it's going any damage, I just wanted to be sure if I use it nearly every time I stop/slow down it would be okay. :confused:
     
    #1 LulzChicken, Aug 6, 2009
  2. jay_man2

    jay_man2 jay_man_also

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    With the regenerative braking you aren't using the brake pads a lot of the time anyway. I only use B mode on steep inclines so I don't have to ride the pedal, and I think that's what it's intended for. If you're driving for max mpg using pulse and glide techniques your use of B mode that way becomes a hindrance, I would think.

    Using B mode like you are would drive me B atty. :p
     
    #2 jay_man2, Aug 6, 2009
  3. jeffcrilly

    jeffcrilly New Member

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    So is B mode basically the same as using engine braking in a manual shift car? Or.. Sometimes in the automatic, I'll shift into "2" when coming down the mountain road... same thing?

    I'm going to do some mountain driving saturday afternoon/eve -- about 4k elevation change over 30 miles of road... fairly steep stuff.. I'm suspecting B should be used on the way down.

    (given that I dont have the detailed manual with my car, any info would be useful.)

    thanks

    jeff
     
    #3 jeffcrilly, Aug 6, 2009
  4. LulzChicken

    LulzChicken Prius Enthusiast

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    Haha ohh okay I understand. I'll just use it on the big hills and such, it's all good. Thanks for the input.

    Yes, that is basically what it does here in the Prius, definitely use B mode on your mountain trips.
     
    #4 LulzChicken, Aug 6, 2009
  5. Holmesman

    Holmesman Junior Member

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    For a detailed explanation go here:
    http://www.techno-fandom.org/~hobbit/cars/b-mode.html

    However, the short answer is that you should NOT use B mode in this way. You actually recover less energy using B mode than you do by using your brakes. B mode is primarily used for slowing the car down on a steep hill, the same way that you would throw a regular car into low gear. I'd recommend that you do not use B mode for braking. I seem to recall reading somewhere that you should use B mode minimally, on hills only. Otherwise, forget it.
     
    #5 Holmesman, Aug 6, 2009
  6. jay_man2

    jay_man2 jay_man_also

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    Yes.
     
    #6 jay_man2, Aug 6, 2009
  7. FireEngineer

    FireEngineer Active Member

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    #7 FireEngineer, Aug 6, 2009
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    I use B to learn where the threshold of regen vs. friction braking occurs. This might be harder on the 2010 because they've made the transition a lot smoother so it's harder to tell when it switches. I thought the HSI would show us (like it does on IMA hybrids) but the CHG bar was still full even though it switched to friction braking.

    Other than that, I rarely use B unless I'm coming down a mountainside.
     
    #8 Tideland Prius, Aug 7, 2009
  9. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    In the 2010, B mode will use about 50% regen per HSI and toss the balance toward spinning the ICE. If you want to spin the engine vs. using friction brakes at the max threshold, B may be useful. I've experimented a couple times w/ this and decided it's no longer worth the habit that I had formed in the Gen 2 doing the same thing.
     
    #9 HTMLSpinnr, Aug 8, 2009
  10. wfolta

    wfolta Active Member

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    Maybe it's pure coincidence, but does the B in the 2010 try to maintain the speed you were going when you engaged it? (Sort of like an engine-braking cruise control.) No mountains nearby so I've only tested it a couple of times on steep hills and it does seem to work that way.
     
    #10 wfolta, Aug 8, 2009
  11. Tideland Prius

    Tideland Prius Moderator of the North
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    Yeah but below 22mph, it was full regen, remember? You press the brake pedal then below 22mph, shift to B. The more to slow down, the less you were regenerating with your foot. Eventually, you'll figure out how much force to apply to the brake pedal such that shifting to B will have no effect on the retardation of the vehicle.
     
    #11 Tideland Prius, Aug 8, 2009
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