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Discussion Starter #1
But being a soon to be (hopefully) 1st time Prius owner, I don't know all the in's and out's of the car yet.

Can anyone explain to me what the "B" is for on the shifter? As far as I can dtermine, it's a "Brake assist" and you use it as a cruise control for going downhill. Am I right or am I totally off-base here?
 

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Porky Pine said:
But being a soon to be (hopefully) 1st time Prius owner, I don't know all the in's and out's of the car yet.

Can anyone explain to me what the "B" is for on the shifter? As far as I can dtermine, it's a "Brake assist" and you use it as a cruise control for going downhill. Am I right or am I totally off-base here?
Porky Pine,
That's not a stupid question at all. Basically, "B" stands for "engine braking" and is meant to help slow the car on long, steep descents. By searching the different categories here you'll find lots of discussion on that very subject. Here's a link to one:

http://www.priusonline.com/viewtopic.ph ... ght=b+mode

Drive happy,
Moo :)
 

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Discussion Starter #3
Ok, I read that thread and I'm still not sure what it does. From the sounds of it, it appears that it's a unneeded function.
 

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Ok. Think of it not so much as engine braking but as Regenerative Braking. It is used most of the time on long decents after you have used quite a bit of your battery power to get up the hill. It does this by using your ABS brakes to tap lightly on the wheels to keep a slightly slower speed as well storing that kinetic energy in the batteries. When going down, you would slap the selector to "B" and then coast down. You get two benefits in that:

1: Regenerate the battery power
2: Save brake life

By using this function properly, you will never have to worry about draining your battery on long drives and steep hills.

So I hope that I have explained it a little better for you. I did not read the article so I am not to sure as to how they did.
 

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Hmmmm. It was my understanding that "B" used the small motor/generator to turn the engine over with out fuel or valves closing(running), causing the drag / brake feel.

In other words, you had to have a pretty good reason (excess and increasing speed / heated brakes beyond regen braking ability / fully charged batt ) to use it.
 

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"B"

>>When going down, you would slap the selector to "B" and then coast down. You get two benefits in that:

1: Regenerate the battery power


I thought it helped with generating power but in John's files he advises against using it as it doe not aid in any capture of energy.

Ron
 

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Porky Pine said:
Ok, I read that thread and I'm still not sure what it does. From the sounds of it, it appears that it's a unneeded function.
Porky Pine,
A search might lead you to a different thread explaining that the "B" mode helps save your brakes on long descents.
Drive happy,
Moo :)
 

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you have regenerative braking when you are coasting in D, too.

except for a few rare circumstances (like going down a bumpy hill), you will get LESS regenerative braking in B as opposed to D.

DO NOT drive around in B all the time - it'll lower your MPG. Use it only on those occasional steep hills, where you're worried about overheating your brakes or gaining too much speed even with the brakes applied. Use it like you would changing to a Low gear in a regular automatic transmission. (There's empirical data around here somewhere from a few folks with Miniscanners who tested charging in D vs. B)
 

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Regenerative Braking....up hill...??...

I am thinking that the "B" gear also has some advantage going up as well as down long grades...

Can some tell me if they KNOW this to be true...or false...??

:roll:
 

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Maybe it's just me.. but your guy's explination would have confused me more... but since i know what B does.. i kindof get your explinations

Basically, this car is always in neutral. When cruising with your foot off the gas, you have a generator that runs... so now you don't cruise too fast.. and it's makes you feel like you have a transmission, since they usualy slow you down when you cruise.

Since you only have a small generator to keep you slowed down.. and no gears, you get going pretty fast when going down steep grades. B.. is a fake "overdrive off" button. Since you're cruising with only a generator slowing you down, you can get going fast. So.. if you switch the car into B.. it will "connect" the engine to the "driveline" and the engine will start turning. There is no fuel running through the engine at this time. It is simply turning.

Anyone here ever try to turn an older engine by turning the fan?.. or try spinning the belt? it's hard. The engine has a lot of reistance while sitting. So.. B "gear" uses this.

B gear is also tricky. It does not run your engine when under 25mph. If you are under 25mph... it will engage your larger electric motor as a generator. This will make you much more electricity. This is the only time B gear help create more electricity. Otherwise, B gear simply makes the engine turn fueless. Which has resistance.. so, it slows you down.
 

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Ignore everything above except Moo and Michelle.

B stands for "engine braking" and allows the car to use the engine compression to slow down, like putting a manual transmission in a lower gear. It will also use regenerative braking, but once the battery is full there is nowhere for generated electricity to go, so on long descents the car would have to use the friction brakes if you are in D.

The only thing you have to know is this: Never use B unless you are on a long downhill. Once you get to the bottom, or any time you are on the level or going uphill, use D.

On the level or uphill, B will not damage the car, but you will get lower mileage, and it will not help anything.
 

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Discussion Starter #12
Ok, thanks guys. I think I understand now. As long as I'm not driving down Mt. Washington, I don't have to worry about it.
 

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Ok, thanks guys. I think I understand now. As long as I'm not driving down Mt. Washington, I don't have to worry about it.
LOL, funny, that's just where I thought it would be a great test.... hehehehe.... Last time I went down Mt. Washington was in a gas-guzzling Pontiac Bonneville...
 
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