Shift position B

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by chesleyn, May 12, 2012.

  1. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    I am not sure there would ever be a time when B mode and EV mode would both be in use.

    B mode is for long downhill drives where Regenerative braking may fill the HV Battery, and so leave you with friction braking. By engaging B mode you 'waste' energy with engine braking, making the regenerative braking last longer and keeping your brake discs cooler.

    EV Mode is best for short moves in parking lots. [Edit: I did not notice that your Prius was a plug in, so your EV mode is worth more than short low speed bursts, but still won't get you to anywhere you need B mode]

    Here is a nearby drive where B mode may be helpful: Renton, WA to Yakima, WA - Google Maps

    From Chinook Pass (5400 feet, marked B on the map) down toward Yakima, (1000 feet) B mode will keep you from cooking your brakes. [EV Mode might get you to Maple Valley]
     
  2. jbrad4

    jbrad4 Active Member

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    I use B all the time when in EV mode to slow the car down approaching slow traffic or a red light. It appears that it IS a more aggressive regen. I can sometimes regain 3 tenths of a mile EV range when using B to slow the car down. I have never been able to gain that much using just the brake. If you are going over 41-43 mph the car turns the engine to help slow you down in B which does nothing for putting energy back into the battery. So, I only use B below 40 mph. -- Mountain driving is something different, and is discussed above.
     
  3. wiggleman

    wiggleman Junior Member

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    When I lived in Hawaii, I used B mode going down those long long hills (I had a 2001 Prius at that time). It effectively recharged the battery by the time I hit the bottom. I have not had the chance to compare it with my new PIP yet. I'll have to find an excuse to head to West Virginia just to see!
     
  4. FUUFNF

    FUUFNF Forum Lurker

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    How fast does slow the car down? I think it may be useful if a cop gets behind you and you want to slow the car down without taping the breaks (and lighting up the brake lights).
     
  5. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    I am still a bit confused about what B does. I understand that with the non-plugin Prius, B mode uses compression engine braking to help you slow down without using the brakes, since the traction battery does not have that much capacity to absorb the energy. But with the plug-in, it would take a VERY long downhill run to fill up the traction battery if it started out "empty". So with the Plug-in, what exactly does B do? Does it always engage compression braking, or does it only do so if the traction battery is "full" and cannot absorb any more energy? Or is it just tweaking the regeneration algorithm to be more aggressive? :confused:
     
  6. mikenewmediary

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    So, I have been ignoring "B" until I read this post. I tried using this with the break if needed, and it appears I get more regen. I was a few miles from the house, with .9 of EV, and was able to make it back using B, and the break. Each time I used it I got back .3, and one time .4 of EV.

    Wondering if anyone else tried this, or could shed some light on the subject.

    thanks










     
  7. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    You will get more aggressive regen, just worse mileage, especially if the engine is used as a brake.
     
  8. The Electric Me

    The Electric Me Go Speed Go!

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    I love "B" mode threads...

    In an effort to clarify understanding they alway morph into 1/2 truths, misunderstandings, and opinions.

    The only thing I come away with, is that surely Toyota needs to do a better job explaining what "B" mode is, how it works, and when to use it.

    But the threads are always entertaining.
     
  9. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    B Mode is simple, never use it unless you are going down a long downhill that will fill your HV Battery, then use it as close to the top as you can.

    Had Toyota been less honest and labeled it L, there would be less confusion.
     
  10. Danny Hamilton

    Danny Hamilton Active Member

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    No. In reverse the Prius uses ONLY an electric motor (MG2) for propulsion. It does not use the Internal Combustion Engine (ICE) at all. Therefore, reverse speed tops out at the top speed of MG2.
    No. While in [N] the Prius supplies no torque via MG1, therefore there is no torque applied to the wheels from the differential. If you switch into [N] while the ICE is not running and coast down a hill, then the Prius will not be able to start up the ICE no matter how fast it gets going. This can become a problem because MG1 can freewheel faster than its rated RPM. Normally if you are not in [N], the Prius will fire up the ICE to reduce the RPM of MG1.

    No. This is why the owners manual indicates that the Prius should not be towed with the front wheels on the ground.
     
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