What is "B" mode, exactly, again?

[attachmentid=2313]My brother quotes me true. Since there has been so much discussion around the function of "B" I though that I would ask the Toyota Rep himself. To his point of increasing he useful miles per tank, I can only assume that by storing away more energy as electrons in the battery than turning it into heat on the pads, discs, and drums, he is able to use the return from the battery instead of liquid fuel.

He went into the planetary gear and wished that he had a cut away model to show, instead he drew it on the back of a paper plate. Incredible is all I have to say about how it functions and wish that I could do it justice trying to explain it myself.

Kaos1

 

Here's what I know from hobbit.
http://techno-fandom.org/%7Ehobbit/cars/b-mode.html

Let me know if I should change my FAQ!

 

As mentioned in my rundown, the japanese-hypermilers-B thing is
most likely an artifact of the Classic, which *did* apply partial
wheel brake pressure under most braking conditions. The '04+
doesn't, so that technique isn't needed for those cars.
.
Darell -- faq is fine as it stands; lemme know if *I* need to take
another editing pass through b-mode.html...
.
_H*

 

have a look at this url.
http://homepage.mac.com/inachan/prius/planet_e.html

 

Thanks for all of the input. It really is disappointing that the Toyota rep himself has got his wires crossed. He did have good intentions though.

Do I have the take home message of forget the "B" and learn to use the brakes.

As I am early on the learning curve with this marvelous piece of technology, I realize that PriusChat is a better source of information than Toyota.

Thanks again,

May all of your hills be down,
all of your winds be tail,
and all of your days be 75F

Kaos1

 

Since that interactive tool doesn't identify what the vehicle itself is actually doing while those various PSD actions occur, I suggest also checking out this webpage... http://john1701a.com/prius/prius-psd_animations.htm

It was created to deal with the incorrect information still being spread. Some instances are just bad assumptions. But the reality that some Toyota employees are doing that definitely justifies taking action to end the opportunities for misconceptions to live on... like this one.

The other benefit is that seeing the flexibility of the PSD stimulates interest to learn more. Most people simply have no idea that level of variety is possible... especially with components that are permanently engaged.

 

Thanks Darrell and Evan for the info!

My understanding of B mode, given I live in the mountains, is that I should use it when going down really steep descents. Same principal as dropping to 2 or 1 as I did in my GMC Jimmy when going down steep hills...just trying to save wear and tear, and prevent overheating of the brakes.

 

It also reduces recharging, which is better for the battery-pack on long decents. Otherwise, you'll encounter that "spin-up" scenario with the engine if you stop immediately after reaching the bottom.

I used "B" the other day on a very steep & long hill, without touching either pedal. It slowed the Prius down so much that I finally had to press the accelerator to regain to a fast coasting speed. "B" works very well for slowing, but definitely not maximum regeneration like you were originally told.

 

yes the main drive motor MG2 is connected to the wheel thru a drive chain and reduction gear set.
yes these are both permanent magnet motor/generators.
as far as I know the "creep" is produced by MG2 (main drive motor) as it's the one connected to the differential.
in the animation if you select THS in green it'll toggle to the TSD11 which is for the new Prius. And you will get the speed of the vehicle by looking at the upper part above the Ring Note it's in km's

 

Using the "B" tonite kept me slow & steady coming down hills in a rather nasty snowstorm, where using the brakes would have caused sliding... as did happen to others. Seemed to keep my charge in the blue - (with defroster, etc.) - whereas I'm usually green on the same stretch of road on other nites.

 

that's right, you guys got snow down there and we didn't get
*anything* up here around beantown. grump.
.
_H*

 

"Using the "B" tonite kept me slow & steady coming down hills in a rather nasty snowstorm, where using the brakes would have caused sliding... "

I'm not sure you can credit B mode for this. Both B and slow braking effectively use only the two front wheels. More aggressive braking would use all four and give more control than the two from B mode.

Does B mode disable VSC or ABS? If so, you also remove two powerful skid control systrems in your car.

 

B doesn't disable the ABS I know for a fact as I was in B on a sand covered paved road and had the ABS kick in. Just as a test when she first got the 2k4 to see if it was different than the 2k1 that it replaced. It's not like 4x4's that disable it when you shift into 4 wheel drive.

 

Greetings,
This is an interesting explanation of the "B". This makes it quite clear about the technique of using B as if the Prius was just a normal automatic. I may never touch it again under normal circumstances. The article also describes the use of B to stop the engine when coming to a complete stop. The use of B at different speeds and state of charge has different effects.

Does anyone concur with this description of B? I have heard so many different tales of its use from Toyota wasting their time installing the feature to it's a miracle.

http://en.wikibooks.org/wiki/Toyota_Prius_driving_tricks

Kaos1

 

Queston about the 04-06:

Forget B for a moment. Focus on using the brake pedal on long steep descents with the gear selecter in D. When the battery is full, what happens to the kenetic energy then? Does it become friction braking? Is it converted into electrical energy then dissapated into the air as heat energy?