electric or not?
#11
Re: electric or not?
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.
#12
Re: electric or not?
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
Thanks,
Matt
#13
Re: electric or not?
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
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.
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
#14
Re: electric or not?
Let's do a simple model that assumes at 35 mph, the car needs only 10 hp to roll down the road say 10 miles:
- Running the ICE at 10 hp over the whole 10 miles, it burns .5 gallons, 20 MPG.
- Running the ICE at 20 hp for 5 miles, it burns .25 gallons but the extra 10 hp is saved in the battery for the rest of the 10 miles, 40 MPG.
(twice of hp) X (half of distance) = same fuel usage
The results is the same 20 MPG for that 10 miles.
Ken@Japan
efficiency@10_hp << efficiency@20_hp
However...
Back to your original math...
- 0.5 gallons used at 10 hp for 10 miles -> 0.25 gallons used at 10 hp for 5 miles
- 0.25 gallons used at 20 hp for 5 miles
How can we get such magic?
Ken@Japan
#15
Re: electric or not?
http://priuschat.com/index.php?showtopic=25759&hl=
Ken@Japan
#16
Re: electric or not?
One of the missing tests, the one that would be terribly informative, would be a P&G benchmark on a given route used to establish the start-to-end speed. Then repeat the same benchmark holding a constant speed that gives the same start-to-end speed.
This benchmark needs to use a non-trivial, flat distance of about 3 miles for each run and multiple samples averaged together. BUT the start-to-end speeds must be kept constant (aka., the same elapsed time interval) changing only the driving method. This type of comparative driving test in a Prius, a head-to-heat comparison of P&G versus constant speed, would be terribly informative.
This benchmark needs to use a non-trivial, flat distance of about 3 miles for each run and multiple samples averaged together. BUT the start-to-end speeds must be kept constant (aka., the same elapsed time interval) changing only the driving method. This type of comparative driving test in a Prius, a head-to-heat comparison of P&G versus constant speed, would be terribly informative.
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!
#17
Re: electric or not?
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.
. . .
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.
. . .
- 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)
- Reproducible results - may entail retesting later with improved protocol
- See #1
- See #1
Bob Wilson
#18
Re: electric or not?
Hi,
The following pulse and glide protocol eliminates the 'foot feather' so we can get consistent, reproducible results:
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:
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
The following pulse and glide protocol eliminates the 'foot feather' so we can get consistent, reproducible results:
- Start at 43 mph on cruise control
- Pull back cruise control to 'suspend' speed control
- At 40 mph, put car in "N" for a ballistics glide
- At 25 mph, put car in "D" and resume cruise control
- When car reaches 43 mph, GOTO first step
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
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
Last edited by bwilson4web; 05-04-2007 at 08:35 PM. Reason: Added graphs and commentary
#19
Re: electric or not?
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!
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!
#20
Re: electric or not?
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?
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?
25-43 mph
25-33 mph
35-43 mph
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.25-33 mph
35-43 mph
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!
Thanks again, and I look forward to working with you!
Bob Wilson
Last edited by bwilson4web; 05-05-2007 at 07:05 AM.