1. Attachments are working again! Check out this thread for more details and to report any other bugs.

is it bad to use [B] a lot to slow down gently?

Discussion in 'Gen 2 Prius Main Forum' started by iseven, Apr 8, 2007.

  1. iseven

    iseven New Member

    Joined:
    Apr 6, 2007
    14
    0
    0
    is it bad to use (downshift) a lot to slow down gently? If this is a very "noob-ish", its because I'm not really a car person.
     
    #1 iseven, Apr 8, 2007
  2. efusco

    efusco Moderator Emeritus
    Staff Member

    Joined:
    Nov 26, 2003
    19,891
    1,193
    9
    Location:
    Nixa, MO
    Vehicle:
    2004 Prius
    Model:
    N/A
    It's not "bad" in the sense that it will do any harm. but it is "bad" in that it will reduce your fuel economy, offers no benefits over regular braking, and defeats some of the built in functionality of the Prius (ie ICE shut off as you slow below 39mph).

    The only place where B offers any true benefit is very long downhill grades where the battery will charge to a maximal level before you reach the bottom and B mode will reduce the need/wear on your friction brakes.
     
    #2 efusco, Apr 8, 2007
  3. larkinmj

    larkinmj New Member

    Joined:
    Jan 31, 2006
    1,996
    5
    0
    I've had my Prius for 14 months and have never used B mode. I wonder if that is typical of Prius drivers?
     
    #3 larkinmj, Apr 8, 2007
  4. iseven

    iseven New Member

    Joined:
    Apr 6, 2007
    14
    0
    0
    <div class='quotetop'>QUOTE(efusco @ Apr 8 2007, 10:50 PM) [snapback]420069[/snapback]</div>
    thank you much. I will be using only when needed.
     
    #4 iseven, Apr 8, 2007
  5. snowdog650

    snowdog650 Member

    Joined:
    Mar 24, 2007
    171
    27
    0
    Location:
    Sacramento, CA
    Vehicle:
    2007 Prius
    Model:
    N/A
    <div class='quotetop'>QUOTE(iseven @ Apr 8 2007, 09:14 PM) [snapback]420076[/snapback]</div>
    You know, I tried using "B" when comning down from the Sierra-Nevada mountains today, and it is NOTHING like engine braking, that is for sure!

    It will help a tiny bit, but be prepared to use some serious amounts of brake pads coming down from Mammoth.

    What do you folks in the Rockies have to say? This was my first time up in the hills ... am I just clueless, or do you find differences as well?
     
    #5 snowdog650, Apr 8, 2007
  6. fshagan

    fshagan Senior Member

    Joined:
    Aug 24, 2005
    1,766
    4
    0
    Location:
    Noneofyourbusiness, CA
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    I use B mode on the Conejo Grade, a steep hill we have here in Ventura County. But I only use it if the traffic is clear and I want to maintain a pretty steady downhill speed.

    Otherwise, I brake lightly, which is using regenerative braking rather than the brake pads, I think!
     
    #6 fshagan, Apr 8, 2007
  7. efusco

    efusco Moderator Emeritus
    Staff Member

    Joined:
    Nov 26, 2003
    19,891
    1,193
    9
    Location:
    Nixa, MO
    Vehicle:
    2004 Prius
    Model:
    N/A
    <div class='quotetop'>QUOTE(snowdog650 @ Apr 8 2007, 11:47 PM) [snapback]420094[/snapback]</div>
    When the battery approaches the 80% SOC mark you're going to be on friction brakes anyway. B-mode will use the engine braking to delay things so you don't hit the 80% mark quite a soon. Using the brakes alone will charge the battery more quickly. Essentially, in B-mode you charge the battery at about 20-30 amps. Using the regen brakes, depending upon the grade you're descending, the charge rate will be more like 40-80amps.
     
    #7 efusco, Apr 9, 2007
(You must log in or sign up to post here.)