The Four Stages of Prius Enlightenment

I suspect that the reason only one motor is shown is because thats the one that can be very illusive as to whether its on or off.. "the 10K motor". They may assume that we are supposed to know when the 50K is on because its only on if we have our foot on the brake... correct?

"Sounds like you are only recommending the dead band procedure when the battery is already full... this way the engine is not making more power than necessary to charge a battery thats already full and reap the associated conversion losses that go along with that too?

But if true, Why would the computer even "let" the ICE charge a battery thats already full, realizing that's a waste and unnessesary?
If the brakes are charging it, thats no bid deal... that energy wasted anyway "and too bad we didn't have a reserve ready", but when its the ICE charging it.. thats a waste?

 

I am suffering from PAS right now but can't wait to see how quickly I move through the stages of Prius enlightenment. I will say it is interesting that some people "get it" quikly while others do not. After my paerents got their Prius I went to see them and test it out (as did my brother) He drove it for about 20 min and averaged 39 MPG, I took the same route for the same time and averaged 49 MPG the first time. I cant wait to see what I can do with mine when it arrives.

 

yeah i started out in energy, then switched to consumption to see what that was all about, then energy to figure out where the power was coming from, then consumption to check out my average trip trends, then back to energy to fine tune the feathering, now it's usually on consumption unless i hit the ev button and haven't switched it back.

funny how many switches you make as you progress up the ladder. i don't know which stage i'm in anymore... maybe i'm in limbo :lol:

 

So far I'm following Dr E's (hey, if you take that space out he's DrE) trajectory pretty closely. I'm a 2 on moving into 3 and as my lovely wife is getting me the EV mod for xmas (no, there are no surprises around here) I'm keeping a closer eye on the SOC to determine how my driving is affecting it and where along my route I might be able to employ the EV. There are several places where I can ping (PnG) but deadbanding has been very elusive because of the terrain and speed limits (one long, massive hill with 55 mph speed limit). It's hard to keep up with traffic going up the hill and not tap into the HV for help. I'll keep at it though. I definitely find myself returning to the Energy screen more and more to make sure I'm pinging and not coasting. If the ICE is running, charging the battery and I'm seeing 99.9 MPG you won't here me whinging, that's for sure!

 

Thanks for that clear explanation!! I was just reading it wrong. I thought, for example, the 15-20 minute bar was for 20 minutes into the trip, not 20 minutes ago. (The manual isn't clear on that point.) I'll start paying more attention to it now.

 

I spend a lot more time on the consumption screen than the energy screen. If I'm deliberately doing "pulse and (no arrows) glide" or looking at the battery state, or wondering why I'm at 35 mpg instead of 50, I'll go to the energy screen, otherwise, I'll be on the consumption screen looking for 99 mpg. The consumption screen feels like a much more concise representation of the combined mpg performance of my car than the energy screen. I don't really care where the energy is coming from if I'm getting more than 50 mpg on the consumption screen. Although if I see 75%, I'll probably flip to the energy screen to try and figure out why, and then flip back to the consumption screen for on-going mpg tracking.

I find that if I stay on the energy screen for any length of time that I really miss the feedback on what the car is doing as a whole...but it sure cand be helpful for answering questions about what the various pieces are doing at the moment.

Works for me, anyways.

-Roger

 

I am solidly in the second stage. I spend a great deal of time viewing the consumption screen and have definitely developed a lightfoot vs my old lead foot. It is truly amazing to see how this car changes your overall driving practices. Someone came to look at my old (15mpg) Sport Trac, keeping my fingers crossed that they will take it of my hands.

 

Ok... so it sounds like the benifit of dead banding is really done while accelerating?

Your basically using the ICE to its maximum capacity without working even more to charge the battery also?
This would in effect accomplish acceleration without the help of the battery and therefore less performance but better mpg efficiency?

If I got all that right, then it would not make sense to dead band on flat stretches because you may loose the opportunity to coast or pulse and glide?... in fact, I'm guessing attempting to keep the ICE on, on flat surfaces would force the car to higher and higher speeds until that majic spot?

Charging the batteries can be reserved for braking or when coasting to a slower speed is really necessary, other wise like you said, the ICE will do it anyway if it gets too low of a charge?

Did I get it that time?.. if not, please correct me and forgive me for being so slow... I always have been slow, but once I get it, I can teach it!..

I'm sure much more will make sense when I am actually driving my car!... still waiting!.... thanks

 

You'll often see that you're getting very good to spectacular gas mileage while the ICE is recharging the battery.

 

I agree. At this point the Prius does not read the terrain, though it could with the Nav Data. Given that you can use your own observation to gain a bet better milage.

 

IF that be the case, it makes sense not to strain the engine above whats needed to do the job..... thanks ....

 

Is there a detailed writeup anywhere on the web describing the pulse and glide technique? I'd like to learn how to do it. How hard would it be to pulse and glide on the highway?

Thanks!

I'm Stage 2 -> 3.

EDIT: I found http://www.toyota.com/html/hybridsynergyvi...l/marathon.html, which is fairly good for 33-40mph. It doesn't describe how a similar technique might be employed on a highway though. I'm guessing deadbanding and then coasting (just enough pedal input to prevent regen) would be as close as you could get, but would this necessarily be better than cruise control at 50-55mph? And if so, what speed range would be optimal?

I realize this post is slightly off-topic, and I apologize. It would be nice to have a single web page to help us "budding Stage 3" owners for all different types of driving (city, highway, different speeds, how to deal with stoplights optimally, etc).

 

Sorry, this is wrong. The motor-generators can work in an amazingly complex variety of combinations. MG2 is connected to the wheels, and usually is the one used to push the car forward or backward and do the regen, while MG1 is the starter and performs "balancing" to allow the engine to turn at speeds independent of the wheels. But people like Wayne Brown and others have documented all sorts of counter-intuitive modes, including ones where MG1 is doing regen, and others that don't "seem" right.

I would not say the battery is "full." Of course, it's never actually full. But it will charge it full enough that there's not enough headroom for a long downhill charging run. And sometimes it will insist on running the engine when it is not needed. Why? Because no computer program is perfect. The car does not "know" anything. It just follows to the T its program, which reads stuff like vehicle speed, engine temp, battery SOC, and performs actions based on them.

I'd recommend against pulse-and-glide on the highway. Pulse-and-glide is for city traffic when you can anticipate stoplights. Accelerate up to speed and then glide to the next light. And anger the drivers in back of you because in the glide stage you slow down below the flow of traffic.

More useful is John1701a's (very educated) opinion that acceleration is most efficient when it's neither very slow nor very fast. Accelerate normally, and then drive the proper speed for the conditions. Then, if the battery SOC is high and your speed is under 42 mph, you can briefly let up on the pedal, and then touch it gently enough that you maintain speed, but the car goes into electric mode. Or, if your speed is under 34 mph and you have the EV button, you can activate that. But I only do this if the SOC is high AND the instantaneous mpg is low, because that means the battery is being agressively recharged. If the mpg is high, EV is not necessary. If it's cold out and you have the heater on, the car does not like to shut off the engine, because the engine is the source of heat for the cabin. Then it's much easier to use the EV switch than the feathering technique, but note the different speed limitation for the two methods.

On the highway pulse-and-glide serves no purpose. You are much better driving a constant speed. Some (few) people find the cruise control too agressive, but I like it. You will occasionally see the engine shut off (of its own accord) on the highway, but this does not happen much. Above 42 mph it must turn (to prevent MG1 from spinning too fast) but it can coast while MG2 pushes the car. But wind resistance at highway speed will take so much out of the battery that the engine will soon start again.

 

Thanks daniel for the excellent explanation.
All I really thought I knew is that mg1 made up to 10K and I didn't really know how its power was applied.... I thought I read coasting activates it for charging 10K worth of possible juice to the batteries. and that mg2 was activated with up to 50K worth of juice from brake regen to the batteries... I was not aware of how it was used for power.

Its pretty facinating learning about how the prius does what it does... many folks don't care and few of us care about the compression ratios etc of a typical ICE engine. But the prius seems for facinating in the respect that it is new technology and you can actually see readouts of what is going on.
I suppose a typical ICE would be so facinating if you had such instrumentation and could actually alter and do something about what you saw.

 

So to summarize you use cruse control on the highway (i.e. greater than 55), that jibes with my most recent observations on the highway. I could not do significantly greater m.p.g. on my one over the cruse control. Yes it is too aggressive on the up hill, but at high way speeds there is not a lot of tolerance for going under the speed limit. I have to say I hate being passed by a semi while in the Rt hand lane. It may be that I did not have the technique, but I have done better in town without causing too much in the way of problems in the city.

 

I was going to post a link to Graham's Prius Page, but my bookmark to that page no longer works. He had diagrams of how the engine, mg1, and mg2 are connected via the planetary power-split device, for a visual explanation of how this can work without a clutch or anything ever disengaging from anything else. Anybody know what's become of Graham's page?

 

I seem to remember a post here to the effect that it was going to get yanked sometime this month. Don't know why. I only read it once, but I read every page. Capital site. I should have downloaded the whole damn thing and saved it here.

hdrygas, I've found that here in Colorado I don't get very good gas mileage with CC on. At least on the highways that I typically drive on. There are some pretty substantial hills and I think that the CC attacks the hills too agressively and knocks the MPGs down a bit. I've had been results when I regulate the speed.

 

You can't pulse and glide above 42 mph because the ICE will spin up and MG1 has to do something to protect itself from spinning too fast (something like 6500 RPM). I have occasionally seen "grey" arrows for a split second at higher speeds but not because of anything that I'm trying to do. PnG wouldn't be as effective anyways because the damn wind resistance at highway speeds would knock your speed down pretty fast methinks.

 

He moved his host from earthlink to ecrostech. Here is the new link: http://www.ecrostech.com/prius/original/PriusFrames.htm