freeeked out in traffic

[qbee42]

<div class='quotetop'>QUOTE(a priori @ Nov 28 2007, 10:46 AM) [snapback]545208[/snapback]</div>

I don't see any reason to use the "B" mode unless I'm driving down a long, steep incline and my battery readout is all greens.
[/b]

On a long, steep incline you want to switch to B mode in advance of a high SOC, otherwise B mode doesn't help. Here is why: When the SOC becomes too high, even in D mode, the control system will start to bleed off excess energy with the ICE, just as it does in B mode. The difference with B mode is that you are telling the controller to get on it now, and not wait until the SOC is too high. This is a form of feed-forward control where you use your knowledge of the road ahead instead of waiting until after the fact. This advanced notice will forestall the use of friction brakes.

Tom

[richard schumacher]

<div class='quotetop'>QUOTE(a priori @ Nov 28 2007, 11:46 AM) [snapback]545208[/snapback]</div>

As I've understood it, there may be circumstances, when driving at very low speeds, where placing the car in "B" mode may get the engine to more quickly charge the traction battery.
[/b]

Even if that's true, why bother? "D" will recharge the battery as needed with no fuel economy hit. A faster recharge is purposeless.

[patsparks]

It is worth remembering the charge display only shows 40% of the scale, even with no bars there is most likely 40% left in the battery and at full green the battery is at 80%. As said earlier, let th HSD look after it.

[GreenIsGood]

I'm kind of curious myself about the B mode but I need to have a clear definition of "long, steep hill." What that means in Western Pennsylvania might be very different than the interpretation of someone in South Carolina. If I'm on a road that's a fairly long downhill (the kind you see signs warning truckers to reduce gear) for 5 or 6 miles, is it smart to put it in B mode?
In my old car, I'd put it in neutral on such occasions just for fun. But are we instead talking about REALLY steep hills?

[a priori]

<div class='quotetop'>QUOTE(richard schumacher @ Nov 28 2007, 04:55 PM) [snapback]545416[/snapback]</div>

Even if that's true, why bother? "D" will recharge the battery as needed with no fuel economy hit. A faster recharge is purposeless.
[/b]

Exactly right! Please don't read my post as a suggestion that "B" mode should be used.

My statement in the post: "I don't see any reason to use the "B" mode unless I'm driving down a long, steep incline and my battery readout is all greens."

Let me clarify: I envision my only use of "B" is when I am going down an incline steep enough to provide numerous warnings about "Steep Grade", extra lanes going the other way (uphill), and "runaway" lanes. Even then, I think I would use it only if the MFD showed all eight bars bright green, my A/C was running full blast, I had miles to go, and the brakes were starting to fade. The HSD's computers know how to handle things, and I'll trust them to do the right thing.

Still -- for more information about the "B" mode, I think folks should read Hobbit's page. I learned enough to simply ignore that letter on the shift knob.


<div class='quotetop'>QUOTE(GreenIsGood @ Nov 28 2007, 07:52 PM) [snapback]545481[/snapback]</div>

I'm kind of curious myself about the B mode but I need to have a clear definition of "long, steep hill."
[/b]

[fwellers]

Ha. I knew my little blurb about using the "B" mode in my panic, would get a little B-mode discussion going.

Good ! I can never get too much B rated discussion



Thanks for all the info. Sounds like the best thing to do is NOTHING. :-))

[richard schumacher]

<div class='quotetop'>QUOTE(GreenIsGood @ Nov 28 2007, 08:52 PM) [snapback]545481[/snapback]</div>

I'm kind of curious myself about the B mode but I need to have a clear definition of "long, steep hill." What that means in Western Pennsylvania might be very different than the interpretation of someone in South Carolina. If I'm on a road that's a fairly long downhill (the kind you see signs warning truckers to reduce gear) for 5 or 6 miles, is it smart to put it in B mode?
In my old car, I'd put it in neutral on such occasions just for fun. But are we instead talking about REALLY steep hills?
[/b]

Use an operational definition: if you find yourself standing on the brake, shift to "B". Or do it if you get weary with hitting the brakes repeatedly, but be prepared to accept reduced fuel economy.

[qbee42]

<div class='quotetop'>QUOTE(GreenIsGood @ Nov 28 2007, 07:52 PM) [snapback]545481[/snapback]</div>

I'm kind of curious myself about the B mode but I need to have a clear definition of "long, steep hill." What that means in Western Pennsylvania might be very different than the interpretation of someone in South Carolina. If I'm on a road that's a fairly long downhill (the kind you see signs warning truckers to reduce gear) for 5 or 6 miles, is it smart to put it in B mode?
In my old car, I'd put it in neutral on such occasions just for fun. But are we instead talking about REALLY steep hills?
[/b]

The "long, steep" definition is variable. It depends on a variety of factors, including current SOC and battery temperature. B mode is good for any hill where braking is required AND you know that the regenerated energy will exceed the capacity of the battery. The only way to know when to use it is by experience. If you find yourself going down hills that max out the battery and cause friction braking to kick in, then next time you can use B mode. There is no hard and fast rule. I've never found a hill in Michigan that needs B mode.

Tom

[KMO]

Alternatively, you could just act like a normal person rather than a Prius owner who only does something if there's an MPG boost, and use B mode for the same reason any other car would use a low gear going downhill - to help keep control of the car...

[theblackbag]

In the UK we have "Select lower gear now" signs at the top of some long steep hills. I act as directed and put the car in B mode till I am at the bottom. I still end up breaking most of the way down the only local hill with this signage (Nether Broughton for those local to Melton Mowbray). I can't remember ever using B in another situation, apart from when I first got the car and wanted to find out what it did.