Still confused about Pulse & Glide

You might consider another approach, if the route permits:

• 1-2 miles - speed about 25-30 mph while the vehicle warms up
• 14 miles - set the cruise control and enjoy the ride, speed of no more than 65 mph
• 1-2 miles - speed about 30 mph while the vehicle uses the stored energy to cruise into work

The advantage is you are just managing the warm-up, letting the hybrid do the cruise and on cool-down, reaping the stored energy.

GOOD LUCK!
Bob Wilson

 

First a couple definitions, using the energy screen:
Pulse = acceleration with arrows from engine to wheels, no battery assist
Glide = no engine, no batteries, no arrows anywhere
Coast = engine is on, no batteries, may show 99 mpg

So Pulse does NOT mean you "stomp on the gas". It's an accelaration, not slow but not hard. Glides generally only work at speeds under 40 mph. Above 41 mph the engine needs to be turning so the electric motor doesn't overspin, so at your speeds, you'll be mostly coasting, not gliding.

"Pulse and coast" may work for you. True P&G, which never goes above 40 mph, would definitely get people behind you upset. But in either case, this is not the difference between your 47 mpg and 80-100 mpg. At your speeds, some people have shown that cruise control will do as well or better than pulse-and-coast (depending on traffic and other conditions).

The 80 mpg+ numbers are generally done in special test cases, not real-world commutes (except for Wayne Gerdes, who does get people upset sometimes). But many people (although still a distinct minority) do get over 60 mpg in everyday commutes. Generally they start with putting higher pressures in their tires (>40 psi) and watching traffic, starting to coast before the areas they know they'll need to slow down in. (Generally you want to avoid using the battery). Then they block the grill and add engine-block-heaters for cold weather, hook up a ScanGauge, add EV button, etc.

With your commute you should be seeing mileages at least in the low 50's in anything above 40'F. Practice accelerating with only arrows from the engine to the wheels when you can, slowing down in advance of using the brakes, and make sure your have tire pressure above the recommended minimum of 35/33. If that doesn't get you above 50 mpg, keep reading the fuel efficiency forum. Blocking the grill in cold weather will help, but it's not worth the effort this time of year.

(Not everybody should expect 50+ mpg. I based this on your longer commute, your medium speeds, and what I know of your local climate).

 

when i accelrate i can rarely get the engine to just put power to the wheel,s the electric comes on and off all the time. I have been in glide, or super glide though..and its cool

 

Ironically this is a very similar route to my daily to and from work and this is almost exactly what I do (when possible) on my route to work. The highway speedlimit for my route through downtown Akron, OH varies from 45 - 55 so I just set the cruise at 50 the entire way. In decent weather conditions it is rare that I don't average 60 MPG and on occasion I'll have a good bump to 75 - 80 MPG due to a favorable tail wind. I would love to see what I would average if we didn't use my Prius as the "family" car.

 

Here is a little game I created to help me internalize the right go-pedal
movement to get no yellow arrows to or from the HV battery. It may help
others too.

I noticed that even under even, steady acceleration sometimes the yellow
arrows went into the battery. Then moments later, they switched to going
the other way. Nowhere had I read what I was supposed to do to get no
arrows. Many posts talked about the no-arrow state, but none I had read
told how to achieve it.

So, I fiddled with very small go-pedal inputs. I found that when the arrow
was pointing up, into the battery, more go-pedal made it go away. When the
arrow pointed down and to the left, out of the battery, letting up on the
go-pedal made it go away.

So what's the game? To make the needed correction I needed to react
instinctively, instantaneously, without thinking. So the game is the arrow is
a snake, let's say a king cobra. When the cobra rears up threateningly, you
step --very, very gently of course -- on its head and he disappears. If the
cobra is slinking away off to the left, you hasten his departure by easing up
on the go-pedal. Kind of childish, but it worked for me.

For me the game was just an intermediate stage. I soon learned to instantly
take the right go-pedal response for up or down arrows without consciously
dealing with the "snake."

One caution, sometimes the display goes into an indeterminate state for a
few seconds with the arrows, snakes, rapidly alternating up and down. Just
hold the go-pedal steady and in a few seconds it settles to up, down,
or none. Then react as appropriate.

 

I know this topic has been beaten to death, but I am bear away I go....:deadhorse:. I am getting better at the "glide", but still cannot get the hang of getting to speed efficiently. (only 1 week on the car). My daily cummute is about 30 miles, almost all highway. I am getting 45+MPG NOT using the cruise and feathering the gas on my own. works great when traffic is moving, but stop and go is a pain. I assume that using the cruise control is not as efficient as manual.

I welcome any info. First tank of gas averaged 46MPG, hope to get better.

Cheers

 

If by highway you mean expressway at speeds above 45 MPH, then "glide" is not possible at all, and you probably want to investigate other meathods such as SHM (Super Highway Mode?)

That really depends on how much effort you want to put into learning and putting into preactice the various manual control techniques that have been found to help. I've found that this time of year without a headwind and no rain, if I use cruise control set at a reasonable speed I am getting better than 55 MPG on a regular basis.

When I attempt manual control of the accelerator I frequently end up with between 50 and 55 MPG, though occasionally I "get it right" and manage a bit over 60 MPG.

 

thanks...I am now feverishly searching super highway mode.....

 

I'll be glad to give you a hands-on driving clinic. Send me a PM if you're interested.

 

I believe the art of accelerating w/o any arrows into or out of the battery is referred to as "dead banding". That might be worth searching as well. The basic idea is that there is an inherent inefficiency related to putting energy into and taking it out of the battery. If you can minimize this, you will maximize efficiency.

It gets tricky, as I believe there are multiple points on the accelerator where it will dead band. I think of it like this, though I'm not sure if its technically correct. As you increase pedal pressure, the system will first sweep through the "gear ratios" of the "CVT" then click the engine RPMs up a notch and sweep again. The ratio is swept by putting in or taking out varying amounts of energy to/from the battery and adding it to or taking it away from the engine power through the MG and the PSD on its way to the wheels. This is almost exactly the opposite of a "normal" car where you would set a gear ratio, then sweep the RPMs, then select the next gear ratio. In general the lower RPMs are the most efficient, so you want to try and dead band within the first few RPM steps generally speaking.

You want to find the dead band that gives you reasonable acceleration, without impacting efficiency too much. I usually accelerate on the first rpm notch up from idle on flat city streets, and the second or third when accelerating up hill or onto a freeway.

Doing all this will definitely help your mileage, but in my experience the single biggest thing you can do is just learn to read the road. I do almost no P&G in the classic sense (bouncing up and down by 10 mph), there is just too much traffic and I don't want to piss people off (and make them waste gas going around me). Instead, I generally just try to anticipate everything as far in advance as possible. If I think the light a block ahead is going to turn red before I get there I will glide or ICE spin as far as I can before braking to the light. This also maximizes the chances that the light will turn back to green before I get there. Then I will dead band accelerate back up to the flow of traffic. I also find that there is a certain amount of play in the pedal over which it will maintain the same speed but get different instant MPGs. I attribute this to the same "gear ratio" effect as above. So once I reach cruising speed, (usually about 43mph on my commute) I will back off the pedal as far as possible bringing the instant MPGs up as high as possible while still maintaining or nearly maintaining speed. Doing this I've gotten as good as 65mpg, and typically 57-78mpg on crowded fast city streets with heavy traffic. When I have to commute on the interstate I just set the cruise at 55 and forget about it. Usually I still get 53-55mpg.

Good Luck, and keep reading and experimenting! Ultimately you have to just try a bunch of things and see whats works best for your specific drive & climate.

Rob

 

Sorry, didn't have a link handy when I posted my comment before.

There's a nice long (121 comments) discussion about SHM over at CleanMPG.com:

New Prius - "Super Highway Mode" Technique (SH). - CleanMPG Forums

SHM requires adding a gauge to the Prius that will report IGN. A common source for this information is the ScanGauge which plugs into the ODBII port.

 

Deadbanding is great in theory, but difficult and unnecessary to hold in practice. As long as acceleration is fast enough to avoid electric-only, and slow enough to keep ICE out of inefficiently high RPM ranges and avoid electric "boost", you'll be OK.

For those without added instrumentation with which to monitor RPM, I suggest keeping instantaneous MPG above half the vehicle speed during acceleration. This keeps things simple and generally will keep you below 2400 RPM.

 

Use JimboK's acceleration advice and drive as if you have no brakes and you'll see a significant bump in your MPG numbers. :bump2:

You can add P&G, roller-coaster, etc. later.

 

States don't all have the same speed limits, and they even vary within a state.

Here in Illinois the posted minimum is 45 on all Interstate expressways. However, the maximum is 65 in some areas, 55 in some areas, and in a few places the maximum is 45.

 

Short path zen:

- Accelerate briskly (this uses the engine most efficiently)
- Gliding (no arrows on "Energy" display) is better than coasting
- Coasting is better than braking
- Braking is better than stopping

 

Aaron,

I recently found myself settling for basically the numbers you are at; I'd have tank averages in the 50-51 range on a good week. From some things I'd read, I had mistakenly arrived at the same idea of "stomp on the gas...". I reread some of the hypergliding articles, and because of some of the recent interest in Wayne Gerde's Chicago to N.Y trip with network tv in tow, I read his article on CleanMPG, An authoritative source on fuel economy and hypermiling on hypermiling, which corrected my thinking. LIke someone already said , when accelarating, keep the arrows from MG's to wheels off as much as possible. I have a 25 mile commute, a lot of it on county roads. My last 270 miles I've averaged 65.5 MPG on my commute to and from work. Temps ranged from 48 def F on morning drive to 70 def F in afternoon. Here's what I did.

1. Kept most accellaration with the no arrows from MG's to wheels.
2. Kept most accellaration with a iMPG of 30 or more.

3. Slowed down. Most county/country roads have a speed limit of 45mph or less.

4. Accellarate to 40mph, glide down to 25 to 30, depending on terrain, traffic, etc.

5. Exercised patience.

These were not the ideal conditions, and I didn't always execute as I should have. I managed the 65 MPG with other traffic on the roads most of the time and spent a few miles on State Hiways each day, which didn't help. The key for me was slower accelaration. I share this to let you know what is possible in a very practical way without perfect execution or circumstances. I hope this helps!