Wow, Bob you are amazing, those gaphs are very well done. From what I gather EV is good for limited circumstances. It can also tax your battery when used to much causing the need for the ICE to run for geration of energy for the battery. Regarding ICE efficency it sounds like I need a tach. for judging efficency. Are these easy to find or install? Can the dealor do it? I read the thread on ICE use for efficency. I gathered that it is best to use so that there is not power coming from the electric motor. Is this true or is there a better way to judge ICE efficency without a tach.

 

My mistake. I just took a short drive and realized my error. As a general rule ICE should be used with no yellow bar to or from the battery. Correct? If you are using battery you are using to much throttle. If you are charging the battery you are not using enough, you should be using more throttle to be more efficient.

Thanks,
Matt

 

Hi Matt,

It is hard for me to say because to the best of my knowledge, no one has done a correlation study between engineering units and the multi-function display. Ken may have some insights for your NHW20 model but I don't even use my MFD in normal driving but rather my Graham miniscanner.

One of my pet peeves is Toyota didn't provide an "engineering" or "diagnostics" mode for the MFD that would show actual units. Worse, the display only shows one motor-generator when we know there are two. So instead, we find our own instrumentation and then gain a clue.

You might check the "Marketing" forum. I think some folks were trying to organize a group buy of the NHW20 scanners. I think it is well worth the money because it gives you much better data than the MFD.

Now to answer your question about the tachometer. Good friend to the Prius, Hobbit has a web page about how to install a tachometer in an NHW20 Prius. It is a little tricky because you don't have a high-tension sparkplug wire to sense the RPMs from. Instead, he shows how to adopt one of these after-market tachometers to run at lower voltages and tap one of the engine ECU signals:

http://www.techno-fandom.org/~hobbit/#prius

There is a lot of excellent information in his web pages.

ENJOY!
Bob Wilson

 

I know the efficiency difference.
However...
Back to your original math...

1. 0.5 gallons used at 10 hp for 10 miles -> 0.25 gallons used at 10 hp for 5 miles
2. 0.25 gallons used at 20 hp for 5 miles

So, your theory is 10 hp and 20 hp use same amount of fuel for 5 miles.
How can we get such magic?

Ken@Japan

 

My recommendation for NHW-20 is Prius CAN Monitor and Logger software for Windows PC.
http://priuschat.com/index.php?showtopic=25759&hl=

Ken@Japan

 

Hello, Bob.

I have been considering doing a test comparing P&G at various speed ranges with one another and with steady speed driving. My goal would be to determine which gives the best overall MPG for a given distance, irrespective of elapsed time. I hadn’t thought to keep elapsed time consistent, but I can build additional tests in.

My proposed test course is 2.7 miles through an industrial park. It’s not a loop, so I would do an out-and-back drive for each method tested. Allowing for time at each end to get up to speed before beginning measurements, I figure the total test to be about 5 miles. It’s pretty flat but not completely so – about 60’ elevation change from one end to the other. But inclines are modest. Here is a link to a map of the course:

http://www.gmap-pedometer.com/?r=918909

About half of the course is four lanes, the other half two. Traffic isn’t bad even on weekdays. (My test would be on a weekend.) But I still have to consider the possibility of traffic on the 2-lane segment requiring either repeat tests or limiting the test to the 4-lane segment. The speed limit throughout is 45 MPH, and folks won’t tolerate my gliding down to 20 MPH or so without being able to pass.

Do you think this course is adequate? It’s about the best I’ve found in this area that offers this combination of terrain, distance, and traffic conditions.

I need some help for the study protocol. Assuming I can make use of the entire 5-mile course, how many samples would you suggest for each method tested? What steady speed would you propose to use? To help this relatively uneducated mind, is there anything in your engineering/mathematical bag of tricks that could prospectively calculate the low and high end of the P&G segments to keep them at the same elapsed time as the steady segment? Or will it need to be trial and error? How closely do the elapsed times need to match?

Looking forward to making this happen!

 

EXCELLENT!! I have some thoughts to share but I've got to scamper off to work. I'll post something later this evening but by all means, this should be a community effort. Some general thoughts:

• use an audio recorder to save the results - keeps hands free and your attention on the traffic around you
• have a checklist that you can 'adjust' as needed - improves consistency
• record everything -- analyze later (minimizes bias during the test)
• analysis of unexpected results can lead to a Nobel Prize (the Bell Labs discovery of background microwave radiation)

I'll try to add more detail later but the priorities should be:

1. Reproducible results - may entail retesting later with improved protocol
2. See #1
3. See #1

This is great! Since I have a similar 2.5 mile course that is a lot flatter, I'll try to replicate your protocol and report the results.

Bob Wilson

 

Hi,

The following pulse and glide protocol eliminates the 'foot feather' so we can get consistent, reproducible results:

1. Start at 43 mph on cruise control
2. Pull back cruise control to 'suspend' speed control
3. At 40 mph, put car in "N" for a ballistics glide
4. At 25 mph, put car in "D" and resume cruise control
5. When car reaches 43 mph, GOTO first step

This is a 25-43 mph, pulse and glide cycle, the maximum speed range that can easily be supported by the cruise control. Cruise control 'turns off' at 23 mph so the 25 mph low end avoids having to reset it each time. The acceleration from 25 mph to 43 mph will always follow the the built-in cruise control profile. The "D" mode coasting from 43 mph to 40 mph will trigger the ICE to stop. The ballistics glide from 40 mph to 25 mph will achieve a uniform, minimum drag coast without special effort.

The only drawback of this protocol is going down a grade in "N" violates many state driving codes. However, like traveling 5 mph over the speed limit, this is not a big deal in most jurisdictions and enforcement risks are a different problem.

There are several variations of this protocol:

• 25-43 -- maximum P&G speed range
• 25-38
• 25-33 -- minimum P&G speed range and minimum speed
• 30-43
• 30-38
• 35-43 -- minimum P&G speed range and maximum speed

This will let us develop a performance model that should allow us to compare P&G to an identical, steady-state speed over the same course in the same conditions.

For practice, not using a terribly flat, access road, I recorded and plotted these 25-43 P&G cycles:


Now it turns out the average speed for these runs is about 33-34 mph and we have some data from last year:


Now I've made some changes to the car since last year so I need to measure both steady-state and pulse-and-glide performance. But now we have a reproducible methodology. Now to find out their relative performance.

Bob Wilson

 

Hi, Bob. Thanks for the detailed response! Some follow-up comments and questions:

It also occurred to me that I could use elapsed time and distance for the P&G segments to calculate speed for the steady speed segments. Therefore I will start with the P&G segments.

For which of the P&G ranges do you suggest a head-to-head, equal elapsed time comparison with steady speeds?

FYI, unless you suggest otherwise, my intent for the steady speed segments is to use CC.

How many samples of each method do you suggest?

I am also going to add tests with normal acceleration, using many of these same P&G ranges. I realize this is less reproducible and probably more variable, but it's more realistic for me and others who don't use CC to accelerate. In daily use I keep my acceleration RPM lower than what you've recorded on your chart. To help with the reproducibility and minimize variation, I will use my ScanGauge to maintain RPM within a certain range, probably in the neighborhood of 1800-2200. This will also help compare acceleration methods and rates for P&G application.

Thanks again, and I look forward to working with you!

 

There are three that have special merit because they are the limits of this protocol:But do the 25-43 mph since it has the greatest speed range. The other one of interest is 35-43 mph since that one gives the fastest average speed. The slowest one, 25-33 mph, is important for those who think the highest MPG numbers is a competition.
I prefer at least three and often will do five and toss out the highest and lowest. The problem is each test takes some investment in time. Given unlimited time, we'd like to get 35 samples but in this case, that is unreasonable and that degree of accuracy is not really worth the investment in time and fuel.
This sounds great! Folks need to realize that the scientific method does not mean we are in 'lock step' to exactly repeat each experiment using exactly the same setup. The variations in different experimental configurations often leads to insights and everyone getting ahead.

Bob Wilson