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Between yesterday and today I have made a new (to me) observation about gliding at highway speeds. Obviously, the car glides a whole lot better when some battery current is used vs. that touchy pure glide state where the battery is not used and the engine is spinning away, bleeding kinetic energy from the wheels. (I tend to shoot for the latter so that the energy doesn't have to be put back into the battery.) What I hadn't anticipated is that there is almost no detectable (seat-of-the-pants) difference between that no-arrows glide state and just lifting my foot all the way off the accelerator. Not at 55-60mph, anyway. I'm half way to abandoning the struggle for pure glide on the highway since it almost always results in inadvertent current draw from the pack.

The question is, can anybody with instrumentation corroborate the observations of my posterior accelerometer? I'm interested principally in how much regeneration occurs during full lift-off at those higher speeds relative to the same state below 41mph where gliding is clearly worth the effort. It feels negligible but I lack the means to know for sure.

Hi Tim:

___Interesting observation but I thought regen really drew her speed down fast vs. Warp-stealth the few times I have been in a Prius-II. In a Prius-I, I did not experiment but threw her into warp stealth anytime heading down without even asking the question.

___Can you perform some coast down tests from 60 to 40. Make the mark on the road, tree, mile-marker, whatever and hit it at 60. Throw her into warp-stealth and see how far she glides before reaching 40. Do the same by just letting off w/ regen and see where 40 mph ends up? Repeat the back and forth 3 or 4 times for repeatability and let us know? I know pack draw during WS has to be made up later but I bet the glide distances are vastly increased and we all want the fuel cut distance vs. the small amount of power to hold the ICE spinning over at a touch under 1,000 RPM. And of course the energy absorbed from 60 to 40 under regen for use later on should somehow be considered but I will take the glide distances at minimal power output over any regen if at all possible myself.

___Interesting question?

___Good Luck

___Wayne

I know pack draw during WS has to be made up later but I bet the glide distances are vastly increased and we all want the fuel cut distance vs. the small amount of power to hold the ICE spinning over at a touch under 1,000 RPM.

This is the part where things get touchy. I do concur that glide distances can be increased dramatically by using the battery under warp stealth. With a fine touch on the accelerator it is possible to modulate deceleration rates continuously within the narrow warp-stealth band. With a SoC right at the nominal 60% you can go from barely decelerating at all (battery providing thrust) down to something that feels like DFCO in a MT vehicle. If the SoC is very high (close to the max) the car will actually drive on battery power alone, accelerating moderately while letting the engine spin cold. That surprised the hell out of me as current levels must be pretty ridiculous in that state. (Need more instrumentation!)

To get back to the point, my problem with that version of warp stealth (invoking current from the pack) is that it is all too easy to eat up significant charge by putting my foot down just a little too hard. I may get a super-long glide on the first hill only to find that SoC has decreased to the point that it refused to WS down the next hill. Meanwhile the engine is idling away in sort of a NICE-on while trickle charging the pack and heating the air. To avoid this for the last week or two I have tried to glide with the pedal right in that hairs-breadth of travel between WS and regen. Glide distances are clearly shorter but I never have to make up for it because the battery only serves the modest 12V needs. My theory is that eating some kinetic energy to spin the engine is a more direct energy path (and more efficient) than sending it back and forth from MG to battery and back, and obviously more efficient than idling. It's a bit counter-intuitive until you consider that the kinetic energy was gained via a high-efficiency pulse under most circumstances. I could be wrong but the numbers have been decent thus far.

Of course none of this would be an issue if the glide limit were 65mph instead of 41mph. We have to throw away some energy under zero load, it's just a matter of how. Maybe Toyota will fix that for the next version?

ok sorry i didn't read your posts but i can explain what i see with my canview


rpm is 950 no matter what when speeds above 42 mph, if I were to warp stealth I'd have to eat 10-20 amps to maintain my glide (or 1.5-3 KW). Under 42 mph you save around a 1KW of power (or 10 amps) so that number while gliding....and I have confirmed that deadbanding USES MORE AMPS THAN JUST FLICKING THE JOYSTICK TO N, so if I want a pure glide using less than 2 amps no accessories i suggest N, otherwise deadbanding will cost you 2-4 amps but that number deminishes to 2-3 once your speed drops below 25 mph and you can increase pedal pressure and still be in a deadbanding state.

ok now I defeat this system by having the engine off and coasting starting below 42 mph and then staying in N even after those speeds. For my generation prius the MG1 limit is raised towards 10000 rpm so the redline is much higher as opposed to the classic prius (which was 7000? correction please). At speeds of 95 km/h I almost saw mg1 peak past 9000 rpm but the best it did was 8000-8500 ish so I didn't think it was an issue since I don't abuse this often enough. But holy crap highway glides are so awesome, your tank score just thanks you!

the hottest i've seen my MG windings and inverter temps are around 55 degrees C, sounds about normal yes? but that was a near peak 38 degrees C day, a first for British Columbia. But now the heat wave died down so overheating isn't even an issue, even my engine coolant never even gets a chance to use itself thanks to the insane cold trips I go through. I can plug at home but as soon as I'm somewhere else I get shot down the drain, WHERE'S MY PLUG?!?!