A few rookie questions

Great pic! I hug my car all the time!

 

Very lucky car! Just think how long it waited for you.

Here are some brief answers.

1. Why do the stereo volume and scan knobs click in? Nothing seems to change when I push them.

They can click in to stay out of the way of your fingers reaching for something else, or out so you can use the rotating knobs. Many of us use controls on the steering wheel for tuning and volume, so never have the knobs sticking out.

2. Is there a way to turn the nav screen off from the steering wheel when the map or info screens are displayed?

If you have Nav, you have a speech button on the right side of the steering wheel. Push it, wait for the beep, and say "Screen off." Changes of climate or audio will display briefly, then the screen will go back off. It is a very different experience from driving with the screen on; less distracting, for one. I recommend it be off while you get used to the car and on when you are ready to get used to the Nav system.

Push the Map button (or Info, or Dest) to turn the screen back on.

3. What is the intended use of the B (engine braking) gear? I assume it wouldn't be an option if it were damaging to the vehicle, but when should I be using it? Why is it better than simply applying the brakes normally?

Downhill is when you use this. The manual says a bit about this, and it is discussed elsewhere on PriusChat. Enjoy!

 

Some answers;
1 they click in to get them out of the was and provide a nicer look. Nothing more than that.
2 I am going to leave this to someone else but I would say no. The buttons on the steering wheel let you jump from one screen to another though. I like to play so I don't want them off. I will check out the manual.
3 B is for long steep down hill runs. It allows the engine to brake the car and actually decreases regeneration. It is somewhat like "jake brakes" the engine compression resists the forward motion of the car. I have used mine just twice going over mountain passes in the rockies. If you don't have real mountains where you live you will never use it.

 

B mode is like downshifting in a regular car. i personally would never use it, but on severe downhills, its possible that you could reach the limit of the SOC of the traction battery and then the regen brakes would not be as effective but you would have the friction brakes that can heat up.

the manual recommends use of B mode sparingly so i fail to see its purpose really.

to reach the max SOC, one would assume a very long hill, but if its that long then its also recommended that B mode not be engaged for any length of time thus elminating that as a recommended course of action.

in my Prius i have gone up and over the Cascades, gone up to Mt Saint Helens and have never experienced a problem with overcharging that some have reported here. maybe just lucky or maybe just an unknown skill i possess.

i strongly suspect the former.

 

I have used 'B' mode to slow the car in non hill situations. With this information from Daniel:

Daniel's article
There are times when I would drop out of S3b if I slow with the brakes but also know I will not be coming anywhere near stopping. I might just need to slow down to 20 or 25 for a short time. The suggestion in this part of Daniel's document is that if I can avoid using the brakes, I will not drop back to S3a. Dropping to s3a would require a 5 to 10 second stop to get to S4 or going over 34 MPH to get back to S3b. Since one of the roads I travel is posted at 30 MPH, and generally has traffic, pushing over 34 MPH may not be possible.

I haven't done any scientific experiments, and I really can only guess that I am in S3b as the car has gone into stealth mode. I have noted that, per another poster's comment, if I DO push over 34 then let it drop back to say 32 and engage CC, the car will happily go into stealth, as long as the temp requirement have been met. If I don't push it over, it doesn't matter what I do, it won't go into stealth. I think this IS the definition of S3a.

 

bruceha_2000 is referring to numbering found in PriusChat's Knowledge Base article on The 5 Stages of Hybrid Operation.

I agree with Tony that comments like "look it up" can be frustrating, but at work I can't take time to cite the articles.

There is at least one thread about taking care of the Prius paint job and avoiding scratches. Glad to see what appears to be a towel protecting your car.

 

I think you're misunderstanding the "any length of time" bit. What is meant is that it's harmful (emissions, fuel consumption) to remain in B mode after you've finished descending the big hill. Five or ten miles of descent is just what it's intended for; the manual is telling you not to drive in B all the time.

BTW, I've had the battery up to full green in only two miles of descent, losing only 200m of altitude (unable to use EV on the approach as I was doing about 40mph). When the battery is full, then Prius automatically uses engine compression to slow down, just as when you engage B. The difference is that without B, it returns to normal when you release the brake pedal.

 

if the valves were closing wouldnt you have back pressure that would aid the fuel pump in sucking fuel and air into the engine?

it almost makes me want to go and overcharge my battery just to see what would happen.

i guess the main reason i have never had an overcharge is because i try not too.

 

Yeah, I'm pretty sure - you can hear it start up (quite obvious in a rocky pass with the windows down and going slowly). It's quite a different sound to the friction brakes.

As far as I know, the valves are actually closed, and no fuel is used (display confirms this), and energy is used compressing the intake air. Ultimately, the power ends up as heat, carried away on the air that's passed through the engine.

 

True. It's a while since I've been in the all-green situation, so it could have been that that I was hearing. But that's usually a lot quieter.

The compression and release of the air in each cylinder. Not as loud as when it's firing fuel, but louder than the valve-open riding in "warp stealth".

One possibility is to increase the life of the pads, but I think that's unlikely. More plausible is to prevent overheating of the brakes - after all, you wouldn't ride the brakes all the way downhill in a conventional vehicle, would you?