What is the B for and when do you use it?

<div class='quotetop'>QUOTE(FishHawk @ Oct 31 2007, 06:26 AM) [snapback]532818[/snapback]</div>

my understanding it's like using 2nd gear going down hill. Electric motor helps by added more resistance( braking )and slows the car down while driving down hill.

 

It is indeed used for engine braking when descending a long steep hill so you don't have to ride your brakes all the way down. I have yet to go down a hill steep enough to use it around here - maybe in the mountains of NH or VT you might use it.

 

Did the other thread say what it was for? There are lots f threads about it, you can use the search function at the top of the page to find lots of answers.

BTW never using B is fine, you are doing good.

 

<div class='quotetop'>QUOTE(patsparks @ Oct 31 2007, 07:11 AM) [snapback]532827[/snapback]</div>

I used B once by mistake, and the ICE did not turn off at a light and it was like driving with the emergency brake on.

 

A guy at the garage asked me what "B" was for. The Prius was in for inspection.

I told him it was the "Jake Brake." He understood immediately what I meant. A "Jake Brake" is what are on some big rig trucks to help slow the truck down by using engine compression.

Harry

 

<div class='quotetop'>QUOTE(Earthling @ Oct 31 2007, 09:24 PM) [snapback]532839[/snapback]</div>

A Jake brake is more correctly a compression brake. It works by opening the exhaust valves when the piston is a top dead centre dumping compressed air into the exhaust so it can not impart force on the top of the piston during the compression stroke thus consuming energy which it dumps. The B position works to do the same thing but not as well. B dumps energy. Some times you do need to dump energy like on a long down hill run when the battery is full, when this happens the HSD will make the internal combustion engine spin via the smaller electric motor in the HSD to dump energy that is excess to storage capacity.
If you stop at the bottom of a hill with an over charged battery the ICE will seem to run but it isn't burning petrol, it is dumping electric.

 

http://www.techno-fandom.org/~hobbit/cars/b-mode.html