Did Prius miss the boat? Stealth operation

Stealth means electric-only propulsion with the engine off (0 RPM).

It's a fundamental part of the FULL hybrid (power split) design and is automatically engaged.

You must be thinking of something else, perhaps pulse & glide.
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It would be harder on the batteries. The batteries are not there to make the Prius an electric vehicle, they are there to allow the ICE to be tuned for very high efficiency (compared to obsolete engines). About 10% higher. They provide power to move the car when the "Atkinson tuned" engine couldn't (low RPM for example) and to enhance the torque at other times.

It's the "lunatic fringe" users who use pulse and glide to get much higher MPG than Toyota intended.

I suspect if Toyota engineers changed the design to utilize pulse and glide automatically it would dramatically change the battery life, and not for the better!

 

they have incorporated much of pulse and glide in gen III.

 

In my mind, "stealth" is achieved while coasting down hill, the ICE is off, no electrical power is being consumed, and no regen power is being stored. The HSI display is completely "blank."

Living in the mountains, I use the technique all the time. I certainly do not want to consume gas with the ICE running on long downhills, I get uncomfortable when the display shows a "full" HV battery. The grades I drive enable me to drive the speed limit climbing the grade, and staying in the "sweet spot" (slightly above the speed limit) for a considerable distance descending. Interestingly, if I take it easy, and do not over accelerate going up the grade,(the displayed mpg does take a "hit") I find that by using the technique described above, the displayed mpg following the descent will be slightly higher than it displayed prior to climbing the mountain.

 

Actually, I'd disagree. The ideal pulse and glide technique will use almost zero electric power. On the other hand, the "just drive it" technique may find you using quite a bit of electric power, depending on the exact conditions. Indeed, the battery is almost always at exactly 6 bars when I drive, while it fluctuates much more when my fiancée drives.

Given the lower fluctuations in battery level, that would also lead to more normal battery temperatures, both of which would extend, not shorten, the battery's lifespan.

 

No arrows is gliding.
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I wonder how long our HV battery is going to last. Living in the mountains, I frequently drive in stealth mode to mostly drain the battery prior to significant descents, on which I then use regen braking to charge the battery to full. When combined with a bit of pulse and glide, this "technique" works wonders for fuel economy; achieving 65+ mpg (displayed) on roundtrips within the mountains is doable. My goal is to keep the gas engine off as much as possible. (The only trouble is, the better I get at this, the weaker my case to add a Nissan LEAF to our stable.)

I'm not actually worried about the HV battery; even if it weren't under warranty, it should be possible to find a salvage replacement for not too much money (~ $500) if/when necessary. The extra gas savings should be more than enough to compensate for a premature battery replacement.

 

Thank you for your comment .... I am just not sure what you are saying? I suppose you are referring to the fact that the same condition is possible while "gliding" whereas I mentioned only coasting down the mountain. And, I agree.

As you well know, anytime you are "gliding" it takes a very small pedal pressure to keep from going into regen (in the mountains that is what I seek to avoid). I wish there was a switch/mode/tool or some way to keep it in the "sweet spot" without manually having to keep the foot on the accelerator pedal and applying just a small pressure. But that is a small inconvenience.

 

shouldn't affect your battery, prius dumps the extra charging. not into the battery. it is well protected from over/under charging in all conditions.

 

Felt - John just means that in a Prius, the semi-official word for no arrows/no energy/whatever on your display is "gliding", and using electric only is a form of "stealth". So what you're doing is considered a glide by most other users.

 

I agree. I always thought of "stealth" as being above 25 mph and not over 41 mph, just bumping the electric motor ever so slightly to maintain speed. Sound right?

 

Any use of pure electric at any speed is considered stealth. Once at and above 42 mph in the Gen II and 46 mph in the Gen III, you enter into the subcategory of warp stealth, still under the stealth umbrella.

Personally I like to believe that there are ninjas somehow involved in this operation.

 

Unfortunately I can't get above 41 mph in "stealth" mode without turning on the engine. I thought all Gen III's were like that?

LOL! Me to.

 

this is what i am trying to say. i think part of the reason the III gets better epa mileage is that the computers are now doing some of the things we have to manually do with our foot on the gas pedal in the II.

 

They are... at first... and then again when you get new tires.

I had been getting up to 46 MPH with the engine off (0 RPM) up until 2 weeks ago, when I replaced the tires. Now, it's back down to 41. This is why we didn't notice the speed increase from 2010 upgrade right away.
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