True glide above 42 MPH Is it possible?

I agree with Patsparks. Ultimately, all of the motive power that the Prius produces comes from the gasoline. Any of it turned into electrical energy and then turned back into motive power, involves efficiency losses. The only exception to this is the kinetic energy that is used to recover electrical energy during deceleration, which is stored in the NiMH traction battery. No one has yet discovered a way to recover energy in gasoline form in a similar fashion.

That, along with the immobilization of the ICE when it is not needed, is the key to the Prius' excellent fuel economy.

 

I'm with Evan. The "hyperstealth glide" that he refers to in fact minimizes conversion losses. Normal warp stealth pulls a continuous 10-15A from the battery (requiring recharging, of course), whereas hyperstealth -- or "warp neutral" as some call it -- reduces that to 1A or less. The technique is designed to keep efficiency losses to an absolute minimum when the car doesn't need to generate power -- i.e., downhill or decelerating. Instead it takes full advantage of kinetic energy, the same as a low speed glide.

 

Bob already covered where vehicle speed input is mostly likely
to come to the hybrid ECU from -- its own motor sensors, and
the "speed sensor" output from the braking ECU having nothing
to do with these thresholds. Said "speed sensor" is the one
that goes to the speedo cluster, the nav system, etc etc.
.
I have touched 67 MPH with the ICE off in neutral. It is
doable. Air resistance kept me from going any faster, and I
strongly suspect that with MG1 close to 10,000 RPM inside
there that there's a nontrivial rotor windage effect that may
actually make warp stealth *more* efficient above some speed
threshold. Viscosity of the tranny fluid through the PSD
may also have an effect.
.
The PHEV conversion folks don't seem particularly concerned about
the lubrication-pump problem.
.
_H*

 

Yep, you are right Evan, I wasn't thinking of the preserving kinetic energy. Only trouble being maintaining a reasonably constant speed against wind drag and tyre drag at that speed. With pulse and glide a true glide would reduce consumption as it would eliminate drain from the traction battery while going down hills therefore less generation required to go back up. I very rarely travel between 68km/h and 105km/h anyway. I have a few km of my commute at 70km/h and 2 km at 80km/h, the rest is 100 for about 8km and the balance up to 60km/h. On the open road it's cruise control at 110 - 114km/h

 

I agree with you, if we all lived in the flatlands.

But in hilly Italy we have many slight downhills where I could glide to 50, 55 mph for miles.... instead at 42 ICE starts, the car goes in hyperstealth and drains the battery until the ice gets gas.

In these cases I cheat: I chuck it N before ice starts. And I keep a cautious eye on the speedometer.

 

So Pat, what average MPG ( or L/100 km) do you get in Cruise Control mode at speeds from 110 - 114 km/hr?

Ron.

 

I get 4.3 l*100 km. 54.7 mpUSg

 

Newbie here,

2007 Pkg #2, 5k miles

I have gotten glide at 52 mph with a COLD ICE after 600 yards, for 3/4 mile.

Could not get it after release off gas, after warn up.

Don't ask me WHY cause I don' t know??

Hobbit?? why??

fred

 

I traced the Japanese NHW-20 Prius schematics.
My conclusion of speed sensor line is...
[speed sensors on each wheel hubs]->[skid control ECU]-(CAN bus)->[GW ECU]-(BEAN bus)->[transmission ECU]-(BEAN bus)->[meter panel computer]->[hybrid ECU and others]

Ken@Japan

 

5.2L/100km on a 600km journey and that included winding it up to 160km/h at one time when I passed a B double and seeing I was at 140km/h I thought I would just keep going. That was on a closed race circuit of course. This was a mostly very flat run between Wingfield, a northern suburb of Adelaide to Port Augusta and back and included some driving in Port Augusta but not much.

 

Do Aussies have a precise speedometer like in USA or a exaggerated (by law) like in the EU?

Hint: my top speed is 181 km/h

 

All,

I've an '06 and I've been up to 81mph in "N". I use "N" a lot and on a daily basis exceed 70 in "N". Knock on wood. I know of a person that has exceeded 90 in "N". Long steep hill was required for this feat.

I have noticed that if you start gliding at a slower speed that while accelerating down a hill, something magical occurs at ~35-36mph. It is like someone took thier foot off of the brake.

I have never paid attention of how fast I'm going when shifting into and out of "N". High speed or low. I had based this on the fact that the dealership informed me that I couldn't hurt anything and that the car had safe guards to prevent damage but he probably didn't realize that I would be doing crazy stuff like this.

Sounds like I should be more careful in the future?!

Kaos1

 

Interesting Stuff!

From the nomogram I have covering my 2008 Prius, 62 mph with the ICE off is driving MG1 as a generator at 10,000 RPM in reverse. Toyota THS II paper describing the improvements in the second generation Prius mentions an upper limit of 10,000 RPM for MG1. That leads me to believe that the ICE and the planetary carrier would have to be rotating to: 1) generate retarding torque on the vehicle and 2) alleviate potential overspeeding of MG1.

Ron

 

Speedo is within 1km/h of my GPS on a straight road using cruise control. Odometer also seems very accurate.

Law here requires a speedo to read +10% to -0% so a speedo can be very accurate or very optimistic.