Hybrid Technology Unique topics related to the 2004 -2009 RX400H model hybrid drivetrain and other features/options found only on the RX400H. Please use the main forum for discussion about shared components with other second generation RX models.

What do I use the "B" gear for?

Old 07-01-07, 08:09 PM
  #1  
hlh1015
Driver School Candidate
Thread Starter
 
hlh1015's Avatar
 
Join Date: Jun 2007
Location: OR
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Question What do I use the "B" gear for?

I read that it's used for engine braking - but that means nothing to me. In what type of situation would I drive using the "B" gear?

Sorry for the silly question, but I've searched this board already & couldn't find the answer.

Thanks much,

heidi
Old 07-01-07, 10:33 PM
  #2  
oldcajun
Racer
 
oldcajun's Avatar
 
Join Date: Feb 2006
Location: AZ
Posts: 1,419
Received 49 Likes on 34 Posts
Default

Use the "B" selector position on a long downhill stretch where the speed in drive is faster than you want to go. I don't use it ofter, but coming down the mountain it helps control vehicle speed without using up the brakes.
Steve
Old 07-01-07, 10:52 PM
  #3  
joedaddy1
Racer
iTrader: (1)
 
joedaddy1's Avatar
 
Join Date: Dec 2005
Location: Orange County
Posts: 1,860
Received 177 Likes on 138 Posts
Default

use it on the mountains.. but not on freeways ( i don't think)
Old 07-02-07, 01:13 AM
  #4  
eleman73
Driver School Candidate
 
eleman73's Avatar
 
Join Date: Jul 2006
Location: VA
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default ...

I have used them several times, it is not engine braking only, it also brakes with electric motors and helps to fill out battery. In fact, with the B shift battery fills up completely, I have never seen it with pedal braking.
Old 07-02-07, 04:53 AM
  #5  
silvervett
Lead Lap
 
silvervett's Avatar
 
Join Date: Mar 2007
Location: Anderson SC
Posts: 508
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by eleman73
I have used them several times, it is not engine braking only, it also brakes with electric motors and helps to fill out battery. In fact, with the B shift battery fills up completely, I have never seen it with pedal braking.
I thought the same thing until I was informed on this forum that you get less battery charging in the "B" mode. I used "B" all the time until was told I was getting less of a battery charge. I have to admit I have never gotten the display to show all bars. I tried using the "B" mode when the car was new on a trip from NY to TX and wasn't able to get all the bars to turn on. On my trip back to NY I didn't use the "B" and still couldn't get all the bars to turn on. I will be driving on flat Long Island for the next couple months so I can't try a long hill in the "B" mode but I will give it a try on my next trip to SC in late August / early September. I would like to see someone that lives in hill country to experiment and report back because I am pretty sure the "B" mode charges the battery less.
Old 07-03-07, 01:07 PM
  #6  
herbvdh
Lexus Test Driver
 
herbvdh's Avatar
 
Join Date: Jun 2002
Location: USA
Posts: 810
Likes: 0
Received 0 Likes on 0 Posts
Smile

In "B" is mainly for lower gear selection on a steep hill where you may loose control of speed. I came down Mount Washington in New Hampshire alternating between D and B.
Old 07-04-07, 07:35 AM
  #7  
hlh1015
Driver School Candidate
Thread Starter
 
hlh1015's Avatar
 
Join Date: Jun 2007
Location: OR
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Default

Cool - thanks much for your replies. I actually live on a steep hill, so I'll give it a shot.

Thx,
Heidi
Old 07-06-07, 09:24 PM
  #8  
silvervett
Lead Lap
 
silvervett's Avatar
 
Join Date: Mar 2007
Location: Anderson SC
Posts: 508
Likes: 0
Received 0 Likes on 0 Posts
Default

I don't understand the whole "B" thing. I may be wrong but I think people are using it unnessarly and it is olnly there for extream situaqtions. If the "B" mode uses the ICE engine's compression to slow the car down you are recovering less energy because the car is being slowed by engine compression and none of it is recovered. In a conventional car low gear is used to keep the brakes from overheating and save pad wear because there is no other way to blead off speed. But if you are in a hybrid and use light pressure on the pedal the electric motor is slowing down the car while it recovers energy. If you do it correctly you should be able to keep the speed down solely by using the electric motor, so if you do it just right not only are you recovering energy you are also not using the brake pad and causing wear and heating the pads. My theory is that it would be more energy efficient to just use the pedal without using "B". By using just the right amount of pressure you can slow the car down without using the break pads and recover more energy. Is my theory correct? My theory is that "B" should only be used on very long very steep down hill runs.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
xclream
ES - 6th Gen (2013-2018)
13
04-17-15 09:55 AM
Sefo
IS - 3rd Gen (2014-present)
4
04-10-15 04:18 AM
zes
ES - 6th Gen (2013-2018)
14
03-13-15 11:47 AM
asrose
Hybrid Technology
4
09-08-12 03:05 AM
CWS
HS 250h Model (2010-2012)
4
04-05-11 08:54 AM


Thread Tools
Search this Thread
Quick Reply: What do I use the "B" gear for?



All times are GMT -7. The time now is 12:02 PM.