2010 Prius Pulse and Glide warp stealth help

I don't think you can get the no arrows state on a GenIII, or at least I can't. I use the HSI and gently apply pedal pressure so there is no indication in either the regen or battery side. I assume this is the "no arrows state". It's the best I can come up with, sorry

 

I also prefer the HSI display over the motor / generator / battery arrow display. Trying to keep the arrows completely off doesn't seem practical. With the HSI display it is easy to control the magnitude of the power flow, keeping it 'close enough' to off when desired.

 

You don't have to stick at no arrow gliding.
Please refer to following my post.
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In Japan, we have been discussing how to pulse&glide on the 3G Prius.

Our conclusion is we don't have to be so sensitive for the zero amp gliding and a weak battery use is acceptable, therefore 0-25% zone on the HSI screen is acceptable.
Also, a slow acceleration is not good for the ICE efficiency, therefore 75-100% zone is recommended for pulsing.

Ken@Japan

 

Neutral is safe at all speeds but not recommended on a downgrade. Most states have vehicle code prohibitions on being in "neutral" when descending a hill. This could lead to legal action should something bad happen that attracted the attention of authorities. Also, acceleration on a downgrade with the engine off can result in exceeding the 'control law' speed limits for MG1 rotation.

Several of us have done the forbidden experiment of coasting downhill in "neutral" and exceeding the reported MG1 rpm. MG1 did not explode nor did the inverter electronics fry. However, the DoE benchmarks indicate that these high rotation speeds, MG1 can generate voltages that exceed the normal operating voltages of the inverter.

In theory, the first failure from excessive voltage might 'smoke' the inverter followed by potentially shorting the traction battery through the remaining melted semiconductor material. But so far, no one has reported this failure mode.

Bob Wilson

 

I enjoyed reading the comments above. There was good advise given.

I am new as well (1900 miles), and after looking at all the displays, finally settled on the HSI screen as being most useful to me. I am not a hypermiler, but I am averaging over 53 mpg to date. I drive pretty much normally, but at a downhill I try to stay in the zone where no line is indicated left or right. I think that is the "sweet spot."

I have indicated elsewhere in Prius Chat, anyone can get better than the EPA average if you live where you can drive for periods of time in the 35-45 mph range and use the "sweet spot" whenever possible. If you do not fill-up too often, but drive, say 250 or more miles between fill-ups, the mileage averages out and occassional trips at 75 mph on the freeway will not hurt the average.

 

There are a few sections of my commute that I can neutral glide a long way (up to 2.2 miles in one section). Surprisingly, the MPGs I get are higher with the car in drive (and holding the HSI bar at the border of CHG and ECO) than with the neutral glide. Also, the traction battery drains with the neutral glide, but not with the car in drive. I have no explanation for either, but for me they are reproducable observations.

 

The pulse zone makes a lot sense. The glide zone seems wrong. I would expect the glide zone should be the entire area left of the white bar.

If your battery is full and you need to sustain 35 MPH for 3 miles it makes more sense to run on 100% on electric power instead of wasting gas pulsing and gliding in the yellow zone in your pic.

 

All of the energy in the battery comes from gasoline. Results of pulse & glide will bury your electric only steady 35, once you account for the fuel needed to restore the state of charge.

 

I thought it came from both regenerative energy and the ICE.

 

And THERE is the rub. If the energy is going to come back from regenerative sources, such as if you know you're about to crest a hill and coast down the other side, it does make a LOT of sense to run the battery all the way down. That way you make enough 'headroom' in the battery to absorb all the energy from the downhill. By keeping the battery two bars from the top, as mine often does, it can fill the battery and force the braking energy to be wasted as heat through the friction brake or ICE compression. This is why the EV mode would be really useful (if it didn't disengage at 25mph), or at least some sort of extended ECO mode where it knew you wanted to run down the battery. The ECU is quite good at managing the battery and ICE, but it does not know the road ahead... and sometimes we could gain a lot more with that knowledge, if only we had a bit more control over whether or not it was trying to maintain the charge in the battery.

 

Yes, but the car acquired its momentum from the ICE. A small yet significant portion of that momentum is recovered through braking. But it still came from the gas tank. As does the air conditioning, stereo, headlights...

I agree with the other reply to your comment here: you know more than the car about upcoming conditions and you should exploit that by making room in the battery to catch regen on big descents.

You don't need or generally want EV MODE to do that, just use the go pedal in an electric portion of the HSI band. This allows higher EV speed (up to 45 in the 2010). The EV MODE limits you to 10 mph cold and 25 mph warm.

In the more general case of normal driving (few hills here in KS), you want to use the ICE in an efficient range, then coax it to shut down by letting off the go pedal and gently reapplying until regen is cancelled. This is a glide; it feels like being in neutral. Contrast a coast, in which the regen simulates the engine braking experienced in non-hybrid cars.

Try pulsing and gliding within a band (say 40 down to 30) with a warm engine, and watch your trip average fuel economy climb with each cycle. With practice it will best any steady state cruising, electric or otherwise. Not suggesting you mess up traffic or anything, but when you get a chance, try it out.

Warp stealth refers to a high speed P&G technique much like the above, but at the higher speeds (above 45), the ICE must turn (and waste energy) in order to protect the MGs. Search for that one after mastering P&G below 45. In warp stealth you pretty much always are drawing from the batteries to spin the ICE instead of in a pure glide. Not as slam bang beneficial as low speed P&G, but still viable.

 

It'll be interesting when someone can do controlled testing of
Ken's ranges vs. my suggestions for P&G, and find out which way
[or a combination of the best techniques from both] wins out in
terms of long-term MPG. Several stray factors will have to be
eliminated, temps and wind taken into account, round-trip route, etc.
.
_H*

 

Absolutely correct that EV mode, in it's current incarnation is not helpful there - sorry if I caused any confusion with that comment. I was more just expressing a beef of mine that I really want a "drain the battery" mode for times like that when I know I need to run down the charge. Using the electric portion of the HSI band will only work if you are on a road flat enough to use the limited amount of power she is willing to give you in that band. There's more to be had, but it will only give you so much. And if I'm on a short uphill with a 40-45mph speed limit, wanting to run down the battery before the big downhill, I often find that I cannot maintain a safe minimum speed without use of the ICE. Of course, the moment the ICE fires, it starts charging the battery also, and removes all my needed headroom in the battery.

I live in the foothills of a mountain, where there are lots of 35-45mph speed limits and rolling hills, so I realize that I am probably not in the common situation. And again, I did not mean to confuse the issue with my gripes about the specifics of my particular driving situation. Keep it in ECO, do what's been mentioned above regarding P&G, and you'll easily get well into the mid to high 50's for mpg.

 

For those of you like me with lots of stop-and-go on hills with the "go" portion being 45 mph, ECO mode is a little impractical. Too many people want to run me down while I'm accelerating.

So, trying to use what I've read the best I can, I accelerate with the fat bar just short of PWR, then ease back to the 3/4 mark of HSI for the remaining pulse. Stealth/Glide with bar in dead band between charge and ECO as much as possible (fat bar disappears).

Also, I tend to use EV mode at the end of my trip to absolutely force the ICE off, since I "think" the forced warmup period might as well be used to recharge the batt since I can't keep the ICE from running then anyway. Is this sound thinking? I can't really see any other use for EV mode that I can't accomplish with the pedal.

After a full tank of this PWR mode approach, I managed 51 mpg. The best I've been able to accomplish in ECO, driving as above, is about 54 mpg. I'm only on my third tank, so I'm still working on technique.

Note: I require constant use of A/C (it's Vegas, summer, and HOT!). Any estimates on how much the A/C costs us in mpg? I would love to get 60 mpg with this car for most of the year.

All-in-all, I'm pretty sure I don't live in an ideal hypermiling environment. Would appreciate any tips that might help me do better here.

Thanks...

 

Set the AC to auto and recirc and 76/78 degrees. It will keep you cool and cut back on gas usage.

 

Thanks. That's about what I've been doing... in auto/recirc between 75-80 depending on how much sun is coming in the windshield.

Following the link in Hobbit's post above suggests that the ECO mode switch helps modify A/C operation in an economical way, so maybe I'll have to learn to live with its sluggishness during the hottest parts of the year.

 

That sounds right in theory, but the efficiency derived from pulse and glide is basically does not have "regen" in the picture at all and the ICE charges the battery only a bit on its way back up to 40mph.

True, energy made from gas is never a pure conversion, but if the ICE has to run anyway, the extra load to charge the battery on its brief duration back up to 40 is very efficient.... mostly because It was going to have to run anyway.

It doesn't always make good sense on paper but reality dictates it works.

 

Ok so just confirm, can the "no arrow" stage be accomplished on the gen III or not? Iv'e been going crazy trying to accomplish this "no arrow" glide, but have not been able to do it on my 2010. Iv'e also tried looking on YouTube but have not found a good tutorial there either.