Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55MPH)?

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

44/44

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

I have to say that this is difficult on a hilly terrain, any suggestions?

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

What does "this" refer to? Difficult for what kind of mileage and at what speeds?

If you don't have instrumentation try the following:

Slight uphill accelerate so that your iMPG = MPH
Moderate uphill accelerate so that your iMPG = 0.8xMPH
Significant uphill iMPG as close to 0.8MPH as possible

Moderate downhill iMPG =1.3 or 1.5xMPH
Significant downhill use Warp stealth also known as yellow arrow condition, by feathering the gas pedal.

Drive with your terrain and do not attempt to overpower it.
Inflate your tires to 0-44 psi.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Do you mean 70mpg at 70mph on the slight uphill accelerate?

That's impossible.

Ken@Japan

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Well the OP hadn't discussed the MPH of interest. The above guide holds from 45 to 60 mph.

Actually I got 70 scangauge mpg highway to highway (miles 4 to 35) on this rather hilly trip to DC, Average speed from measurement to measurement ~50 mph. Obviously scanguage MPG is not entirely trustworthy, but I think the strategy you see in the graph below and was outlined to the OP in my previous post is superior to IGN for this sort of terrain.



60@60 on hilly terrain should be possible on this, but not with IGN measurements.

My guess is that 65@65 on more mild terrain might also be possible using 15.0 kW pulses and 8.0 kW "glides".

It would be awesome to have a plot of kW alongside this, but I haven't found any developer interested. These apps are mostly written for bicyclers and hikers.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

60@60 on flat road is possible.
65@65 on slight uphill is impossible.
These are not technique, but they are physics on the Prius fuel efficiency limitations.

Ken@Japan

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

The poster at number 62 doesn't have a mpg readout anyway... priuses sold in Canada display litres per 100 km, so that trick doesn't work.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

So I think there's a misunderstanding here. I wonder if your 60@60 projection assumes that all of the energy of the ICE is lost. But as we know it isn't, it is stored in the traction battery.

Overall car efficiency can be higher than 60@60.

Just today I got [email protected] on very hilly terrain with A/C at 77. I'm pretty certain that the would do better in absolutely flat terrains. If you're interested in my measurements and trip or have any suggestions have a look

http://priuschat.com/forums/gen-ii-...ix-mile-highway-trip-flats-hills-results.html

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

That's good number.
I'm not saying 60@60 is absolute maximum number.
There is a few percent variance.

But, Prius requires 25% or more energy at 65mph than 60mph.
So, I'm saying 48mpg@65mph on flat road is possible.
65mpg@65mph on slight uphill is impossible.

Ken@Japan

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

So are these numbers that you mention empirically derived? Do they take the contribution of the inverter-derived kinetic energy into consideration?

So far I have gotten 70@54 and 62@61. There definitely seems to be a significant fall-off. Well, I'll be doing the identical trip next week again. I think I can get 55-58@65, but maintaining that average speed is tricky because the speed limit is 55 in some parts of the trip.

I will test the first 60 mile hills @65 mph

And I need an app that also tracks instant kW output and impg, then we can talk more scientifically I don't think I claimed 65@65 on an uphill, but I do think that with ideal hills (sharp uphill, protracted downhill for WS) the Prius can do better than 60@60.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

We're not splitting hairs.

60@60 is a theoretical figure that can be improved. The original hypermilers who paved the way for much of this practiced mostly in flat terrain, there were no GPS-based smartphone apps to accurately measure and track speed and elevation (heck there were barely any smartphones then) and based their measurements on the poorly refreshing broad IGN measurement.

I believe 60@60 may be applicable in many conditions because it is averaging many errors/assumptions that push FE in different ways, not because it is the car's optimal performance.

60@65 is feasible (and perhaps higher) but I have no flat terrain or "perfect" hills in which to test these with 3+ hours from where I live. In fact if you noticed I even negotiated tolls in my measurements which reduce average speed and FE. Hobbit's sweet spot refinement is a good step towards that direction.

Note that Hobbit never really mentioned anything about 70 mpg at 66-68 mph or claimed to have accurately tracked average moving speed during any of his measurements. Also this thread that is titled in a way that suggests that speeding at 66-68 mph will be more FE than 50-55 which is not possible with this engine.

Anyhow I look forward to any project that tracks and collects our experience. I'll be taking the same trip on Tuesday again, though my priority is to find a way to track speed in the first 68 miles of the trip without including tolls in my measurements.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

No becayse slowing down (not stopping, I use electronic tolls with a remote box payment) for the tolls 3 times will remain included in the measurements of average speed and average mpg. The only way is to stop the measurement when I begin to slow down for the toll and take a note of the mpg at that time. After I get up to ~65 mph then I can reset the MFD mpg and start a new measurement of average speed.

I understand why, but it would be a comparison with a "worse" result and would be highly restrictive for the terrain because maintaining the speed in steep hills (first part of the trip) will require 20+ kw from teh ICE regularly, while it should be acceptable in the shorter hills.

Maybe I will do manual in the steep hills and cruise control in the short hills. Will think about it.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Actually I do, I bought my car in the US. I also have a scangauge. I find that with the hilly terrain I get better results with lower speeds, but I can only do the lower speeds at night when it's not busy.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

That number is not scientific guess.
Prius engine efficiency is max 37% and approx 30% in the real world.
The attached example is 32km/L (75.3mpg) at 80km/h (49.7mph) data, which tells us the engine efficiency was 29.6%.

Prius requires 15.2kW at 65mph, then the calculated number is 47mpg at 30% efficiency and the absolute max number is 57.8mpg at 37% max efficiency.

Ken@Japan

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

To get better fuel efficiency I like comparing
the ScangaugeII's GPH and SoC with the MPH. I
try to keep the accelerator pressure low so that
the GPH is under 1.10 most of the time and I
try to keep my top acceleration under 1.50. Whenever
the SoC drops below 50% - I apply the accelerator
pedal more aggressively to charge the batteries
rather than having the Prius automatically recharge
the batteries because when the Prius automatically
recharges the batteries the FE drops about
3 to 5 mpg!

To get to the desired MPH - I try to synch
my accelerations with a downhill grade of the
road or a flat section of the road to lessen
the effects of gravity on FE. To improve
my FE when driving uphill I try to practice
NICE hypermiling techniques but I'm not always
coordinated enough to do it right all the time.

If the weather get colder than 50 F - I have
to watch the coolant temperature via FWT
to make sure the ICE doesn't get too cold
beyond grill blocking - if the FWT starts to
drop below 130 F - I run the ICE more
aggressively to keep the engine coolant
warm so I can avoid having the Prius
automatically try to heat up the engine.
When the Prius automatically heats up the
coolant it does so more aggressively and the
colder the outside temperature the greater
the FE can drop.

On road trips I found that when using cruise
control (CC) along the PA/OH turnpike that
setting my speed to about 53 mph achieved
about 64 mpg and 55 mph still got me about
62 mpg with zero effort. When I increased
the CC speed to about 60 mph the FE dropped
to about 58 mpg ( 87 oct E10 gas, outside
temperature 70F, no grill blocking, Tire Pressure
set at 48 psi front and 44 psi rear, my PA/OH
turnpike road trip is about 560 miles and takes
me all day to complete as I am going from
Washington DC to Detroit MI, mpg # are
calculated, my MFD mpg were slightly higher )

hope this helps

Walter Lee, neophyte hypermiler
2010 Toyota Prius III Oem floormats
Blue Ribbon/Dark Grey
Yokohama Avid S33 ( 48 psi / 44 psi)
ScangaugeII (AVG, RPM/FWT, SoC, GPH)
<== currently miscalibrated!
md/dc/va area
odeo +12800 miles/about 59 mpg

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Walter, except for the last paragraph, I don't think any of that applies to the higher speed topic. You'll likely never get under 50% SOC on the highway, you can't drive in neutral uphill (not sure if I read that right :-D), and if you're driving highway speeds the coolant getting way too cold isn't much of a concern.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Trying a mixed bag of both 65-67 and 50-55 based on traffic speed during commute and stretches.

Getting ~57MPG Without over thinking things and geeking out with stats and acronyms(maybe a few), I keep it simple without any gauges other than the MFD (OK an acronym

1) Uphill - try to keep the acceleration such that iMPG doesn't go lower than half the MPH. I lose a few MPH slowly depending on the hill. Alternatively, if I am getting pressure from the traffic behind, I'll accelerate similarly to just past the crest(if there is a downgrade on the other side) to gain momentum and glide further.
2) Level - I'll get up to 65-68 and max iMPG to maintain that speed while taking advantage of opportunity/need to glide. VERY slow acceleration as needed maxing iMPG while doing so
3) Downhill - Glide with either the slightest pedal down to cause slow gain in speed while maintaining 99.9 iMPG. Call it finding that edge just before iMPG lowers thus gaining speed/momentum along the way At times, I'll scavenge some regen with foot off petal if traffic ahead/down hill appears to be less than my gained speed increasing SOC

I personally cannot drive in the low 50MPH range on the major highways to work. Slow lane can be 65MPH, so using all the techniques as applicable is the best bet.

Finally, for the life of me I cannot find that stealth sweet spot(pure coast/no arrows/no energy flow on MFD) between ICE on and charge!?#$ I'm going to try my laptop and some PriusCANMonitor for ELM237 to gauge RPM, etc. and see how much more I can squeeze out. BTW, 41/40PSI on new Goodyear Assurance Fuel Max LRR tires I just got for a steal w/new 2011 15" rims/caps )