Deadbanding over 40 mph

Isn't this "gliding" that everyone's always raving about?

 

Which reminds me that I don't completely understand the "warp stealth" concept, but I do understand that when I get on the Interstate going downhill I can accelerate to about 45 with the ICE, coast for a second to turn it off, and then accelerate through to 55 or 60 gently using the electric drive to increase the speed.

On level ground the electric will only get you to 42 and then the ICE comes on, but going downhill you can coast or use the electric very gently and keep the ICE off at much higher speeds.

I get on the Interstate every morning in a nice downhill place and often get 99+ mpg bars there. I get about 37 mpg going the other way in the evenings.

To me it seems like the hilliness here would help mileage, but there's no choice at all about running the ICE on the uphills, so that may not be the case.

<div class='quotetop'>QUOTE(efusco @ Mar 19 2007, 04:00 PM) [snapback]408517[/snapback]</div>

 

'07 Prius, 3500 miles. I can pulse and glide, I can stealth, I can warp stealth... but I have not yet gotten it to glide when moving over 42 mph. Over that speed with a light touch to the accelerator, I get a choice between warp stealth and coast-regen, no glide between the two like you get <42mph.

 

<div class='quotetop'>QUOTE(wyounger @ Mar 24 2007, 03:24 PM) [snapback]411567[/snapback]</div>

Somebody please post definitions for these different modes.
Thanx,
Carl

 

<div class='quotetop'>QUOTE(malibucarl @ Mar 24 2007, 01:21 PM) [snapback]411586[/snapback]</div>

Stealth = no arrows on the screen, speed 42mph or less.

Pulse and glide = accelerate (using electric or gas, but don't loaf the engine in the latter) to an upper limit, then stealth until you reach a lower limit, then accelerate back up to upper limit and repeat. The bread-and-butter technique of hypermilers. The longer you can glide and the lower the speed you can tolerate, the better you'll do, but P&G with 40 and 22 as limits will drive other people *nuts*.

Warp stealth = arrow from battery through generator to wheels, speed above 42mph. The engine is still spinning (necessary to keep MG1 below 6000rpm), but no fuel is being consumed.

Coast-regen = foot completely off accelerator, so there are arrows going from tires to battery.

I just cracked 2000 miles. I *have* observed no arrows above 42, but to be honest, I don't really try for it.

 

I'm finding with my Can-View that to get warp stealth and warp gliding above 41MPH you have to have very precise control over your foot and the pedal.

For an example the pedal position is from %0-%100. %0 is foot off the pedal. %100 is pushing the pedal all the way to the floor.

To get warp stealth you must be between %1 and %10

To get warp glide you have to keep your foot at %1!! Very hard to do.

This is just my observations. I can usually get into warp stealth %99 of the time that I try.

 

<div class='quotetop'>QUOTE(wyounger @ Mar 24 2007, 03:24 PM) [snapback]411567[/snapback]</div>

You won't see it on the display at >42mph. It will almost always indicate energy moving from the battery to the wheels. I say "almost" because I have seen no arrows at higher speeds, but it's happened maybe twice and I'm not entirely convinced that it was anything other than the display catching up with what the drivetrain was actually doing.

 

<div class='quotetop'>QUOTE(orangeblood @ Mar 19 2007, 02:30 PM) [snapback]408501[/snapback]</div>

I seem to remember reading that the "Dead band" mode is unavailable above 39 mph. Above this speed the ICE comes on and suppliments all modes of operations.

 

The ICE does trun I think at 950rpm but there is no fuel going to it.

 

<div class='quotetop'>QUOTE(sharkmeister @ Mar 19 2007, 01:22 PM) [snapback]408532[/snapback]</div>

"Warp stealth" is, in my opinion, a very poor choice of words, likely to increase confusion. Above 42 mph, the engine must turn, and in order for it to turn, some fuel must burn. But it's an insignificant amount of fuel and will not show on the MFD (further adding to the confusion).

Aside from the miniscule amount of fuel needed to turn the engine above 42 mph, the Prius is capable of operating on electric power at any speed. But since wind resistance increases exponentially with speed, and the gas engine is more efficient at high levels of power demand, so-called "warp stealth" is uncommon, and when it happens, is more likely to be when downhill driving reduces the power demand.

It's also worth noting that the arrows on the MFD are not always a reliable indication of what's happening in the car's innards. Sometimes the engine can be running and yet there's no arrow out of it. And on the freeway, the MFD shows a very slow back and forth between charging and discharging, whereas the more responsive CAN-View shows an extremely rapid back and forth. The CAN-View also shows discharging at some times when the MFD fails to show an arrow out of the battery, and I suspect the opposite may be true as well.

 

<div class='quotetop'>QUOTE(daniel @ Mar 25 2007, 01:11 PM) [snapback]411896[/snapback]</div>

That's not quite true. Under zero load the ICE will turn, but if there's sufficient battery power the car will just turn it using the electric motor instead of idling. To check this (and other things) I installed an analog tachometer that gets its information from the ECU's ignition signal. Under "warp stealth" (feathered accelerator above 42mph) the tach drops to zero, meaning that the spark plugs aren't doing anything. The ECU wouldn't dump fuel into the cylinder without trying to burn it, so it's a very safe bet that injection does actually stop.