Hybrid Gas Mileage Good? Bad? As Expected?
Hybrid owners - how has your gas mileage been? Better than you expected? Worse?
0
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Comments
http://homepage.mac.com/priustech/Prius/Menu9.html
___Let me attempt to enlighten you a bit
___There is a Real Hybrid Mileage Database over at Greenhybrid.com and it would behoove you to take a glance over the various automobiles listed
___Let me give you just a few highlights as to what can be found there in case you don’t think the HCH and the Insight by inference are not real hybrid’s
10 Honda Insight’s are posted with 4 beating the EPA combined estimate of 64 mpg.
55 Toyota Prius II’s are posted with just 4 beating the EPA combined estimate of 55 mpg.
37 Honda Civic Hybrid’s are posted with 20 beating the EPA combined estimate of 48 mpg.
6 Toyota Prius I’s are posted with just 1 beating the EPA combined estimate of 48 mpg.
___I am sure more Prius II pilots will begin to achieve the magic 55 mpg number as there are quite a few knocking on the door as of this writing.
___Do you know of any Prius or Prius II’s that have set world records in the last 4 + years? I know of a particular Insight that did just 2 weeks ago ;-)
___Lastly, I have a lmpg more then double that of the Prius II’s CR average so please hold your thoughts about the Honda’s not being real hybrid’s until you see what is actually doable by those supposed non-Hybrid’s.
___Finally, Hybrid’s are achieving the EPA estimates posted if driven and setup properly. There is also a much higher percentage of non-Hybrid pilots that have achieved this task without all the setups and techniques used by us Hypermiler’s.
___Good Luck
___Wayne R. Gerdes
A true hybrid means that a vehicle can run "Independently" on either gas or electric or both. Only the Prius can do that.
___Really? Did you know that a 2000 Honda Insight could travel ~ 1 mile on the pack alone after you have ran out of fuel? Not with today’s latest ECU updates as Honda took that capability away but it can. What does that make it? A non-hybrid? An all electric “BEV” for short? A pure Hybrid?
Doing research on the hybrids, everything I have read so far has recommended the Prius over the Honda hybrids when everything is taken into consideration. Why else would Ford and Nissan among others, license Toyotas' Hybrid Synergy Drive system to use in their own vehicles.
___If you would have done your research properly, you would have found that a Prius will never pay for its increased costs by fuel savings alone. Why not consider an 04 Accord or Camry PZEV instead? Larger, safer, better performing, much less expensive, and just as green if you purchase one from any of the following including California, New York, Vermont, Maine, or Massachusetts.
As a point of reference, I did check with greenhybrid.com and the Prius still bests the HCH by 1.5 mpg according to them.
___1.5 mpg difference between the Prius II because it is a Hybrid vs. an HCH because it is a non-Hybrid according to you? What is the Prius I since it is achieving just 1.5 mpg less then the Prius II by those documenting their tank data? An also ran?
The HCH is classified as a Compact car, whereas the Prius is classified as a Midsize car. No contest there.
___Not only is the Ford Focus ZX3/ZX5 a compact, it is also larger then the Prius II. Interesting point, isn’t it. I believe Autoweek is now classifying the Prius II as a Compact now given the way Toyota designed it around the EPA cabin specs.
The Insight may get higher mileage, but it certainly isn't a family car, being only a 2 seater. If you are happy with a Honda hybrid, that's great, that you too are a environmentally conscious person that wants to save our planet. To me though, the Prius is head and shoulders above the others ...
___I loved the part about may get higher mileage. Give the average owner a 5-speed Insight and a Prius II and there isn’t any may about it ;-)
___Since this thread is supposed to be about gas mileage, the Prius II isn’t giving its owners anywhere near EPA estimates for most purchasers whereas for greater then ½ of those reporting tank over tank from their HCH’s, it is? In both cases, they offer great fuel economy but make sure you understand the above before making any conclusions about your own research
___Personally, I would love to remove all the Hybrid HW from my Insight. I would be receiving even more then double what you might receive in your daily single occupant commute in a Prius II. Place a 1.0 L Honda designed iCDTi in her and she would be good for 150 mpg. Even my 03 Corolla LE w/ Auto’s last tank beat most Hybrid drivers last tank Best practice for fuel economy in a true mid-size automobile? A 2.2 L iCDTi Honda Accord from Europe. Best practice for cleaning the air with low emission standards? Any affordable and available PZEV and not just the Prius II which is slowest car in the entire Toyota lineup available here in the states! Not to mention it is also one of the most costly in comparison to what you can pick up a Toyota Echo, Corolla, or Camry for. Maybe Toyota should place the Corolla’s 1.8 L ICE in the Camry for better fuel economy and ~ the same performance as that of the Prius II? How about placing the 1.5 L from the Echo in the Corolla to match the Prius II’s performance and increase its fuel economy possibly? What about placing the 1.5 L atkinsonized PZEV of the Prius II in an Echo w/ a stick? All 3 would offer even closer fuel economy to that of the Prius II if not better in the case of the Echo but for thousands to tens of thousands of dollars less cost and have similar performance. So what is your point?
___Wayne R. Gerdes
I would have sworn I read somewhere that Honda licensed some part of their Hybrid technology from Toyota. I think it was on the Insight only. That was back in 2000 when they both hit our market.
PSD is way too complex? Differential has at least one Planetary gearset. Automatic transmissions have at least 3 Planetary gearsets. If you are having trouble understand PSD, animation might help.
The car at rest. The wheels(purple ring) does not move. Therefore, the MG1(yellow) is generating electricity. If HSD does not need to recharge battery, it'll just shut down everything.
--------------------
Accelerating. Remember, HSD E-CVT do not shift gears. So, instead of downshifting(increase in torque), HSD taps into high torque 50kw MG2. As you can see below, the wheels starts to move and the MG1 is still generating electricity. That electricity combined with the battery power the MG2 to provide 295lbs-ft torque! This set up allows Prius to have smaller battery since MG1 can also generate on-the-fly.
For more info: http://home.earthlink.net/~graham1/MyToyotaPrius/Understanding/Co- ntents.htm
"the PSD has dreadful efficiency at low speed where it could be performing better. (Too much power churning.) Fortunately there is a better way. The Series Hybrid offers a path to make serious advances in vehicle propulsion."
HSD is series-parallel hybrid design. It has advantages of both series and parallel hybrid designs. At low speed, it can run on pure electric and recharge battery when needed. This characteristic is that of a series hybrid. When more power is demanded, combined effort of ICE and electric motors were put into use. This characteristic is that of a parallel hybrid.
Dennis
___Here is an entirely different take on the whole Hybrid fuel economy discussion.
___Tell you what Let’s put a little wager on your more efficient HSD drivetrain theory in the real world. When you do in fact purchase a Prius II, I will lay $100 cold ones on the fact that Misterme and his HCH w/ CVT will clean the floor with you over a given lengthy distance or terrain in the fuel economy or absolute range department. Other then deep inside a city possibly given the Prius can run for a few blocks on the pack alone If you would care to take on my Insight, well let’s just say I will up the wager just for the excitement of it all. Let us say title for title? And you can drive 35 mph or less if you would like 8-) To make it even more interesting, I will even spot you 500 miles in a total range run!
___As it stands, I know > half of the HCH owners that are reporting tank over tank in the real world hybrid database are beating EPA combined estimates. The Prius is a bit tougher nut to crack as has been mentioned so many times before. It is just tougher to reach 55 mpg as a lifetime average in one is all When and or if you finally do hit 52 mpg and with a range of over 750 miles, you might just begin to compete with my lowly 03 Corolla w/ Auto!
___Fortunately for all hybrid drivers no matter if it’s in the HCH, Insight, or Prius, we have a few tricks available to us that our regular ICE brethren don’t have access too. With a bit of practice, these things (hybrid’s) will kill a regular ICE when setup and driven properly. The big word is if setup and driven properly
___Good Luck
___Wayne R. Gerdes
Putting up a fight between me and Misterme? No, thanks but nice try.
Dennis
___Not a fight in the least but a simple hybrid against hybrid run for mileage or range. I know Misterme places his and his HCH’s capabilities on the line each and every day as he drives to work and back. That 800 foot climb to and from is one nasty SOB as well! You on the other hand seem to speak accolades about a particular Hybrid from behind a PC monitor instead of the windscreen like the rest of us in the real world
___Or you could always take me on in a Hybrid for Hybrid grab. I wonder what I could Ebay a brand new Prius II for anyway ;-)
___Good Luck
___Wayne R. Gerdes
A cheap personal attack. You do this when you are in the loosing side of the argument. Did VCM discussion broke the last straw? We all know your pattern now, Wayne. You are incapable of connecting dots to get the big picture. That is the very reason you fail to see the long-term. Your car engine power and fuel economy estimates are way off as well. I am not going to zoom low down to your personal attacking level and pull out "your wife card" on you because you can beat me with experience. Delete msg#22 or I am going to ask a moderator to do so.
Dennis
Dennis
P.S: On mid Aug, I am off to Cancun for a week.
Hatchback
Smart/Entry
Stealth Mode (I can travel 42 MPG on electric.. can you?)
Built in NAV
Way better rear seating
Vehicle Stability Control
Nifty buttons on the steering wheel for climate contol, radio etc
Great styling (can't argue with the Prius's success!)
Electric A/C (what does yours have?)
Bluetooth (WAY cool feature)
..and that marvelous feature of the "START" button... a wonderful often missed safety feature of the Prius (NO KEY TO JAB YOU in an accident)
Shall I go on... or is it hurting too much?
I go by the major mags and consumer reports and ALL of them got better mileage with the Prius. You know something? Even if the HCH DID get better mileage than a Prius.. I'd STILL get the Prius!
I suggest he go to the Honda board to expouse his Hondas' virtues. I stand by my statements made
previously. See #14. Thank you...
I thought you didn't want to continue comparision between HCH and Prius. Wait, what comparison? Consumer Report compared 4 door family sedan and HCH didn't make it there because the acceleration of HCH is too slow. In that comparison, Prius gets double the mileage than other cars that were compared to. MPG is not the only thing in the equation. Every little things add up and the bigger and more powerful the hybrids get, the more difference you will see.
It looks like IMA HAH tuned for power is starting to lack in the low emission department already while HSD SUVs with more power, are still going to be super ultra low emission.
It would be nice if Emunds has online database of each vehicle fuel economy. BTW, HCH should be compared to the classic Prius because they both are compact sedans. In real world, I believe even classic Prius gets better mpg than HCH.
Dennis
A cheap personal attack. You do this when you are in the loosing side of the argument.
___Given you apparently don’t own a hybrid, have probably never driven a hybrid, and are probably afraid of losing the real world challenge I offered, I would say you have much to learn about real world hybrid efficiencies. In other words, the real world is a lot more relevant imho.
You are incapable of connecting dots to get the big picture. That is the very reason you fail to see the long-term. Your car engine power and fuel economy estimates are way off as well.
___Really? Like how the Prius is the slowest of all Toyota sedans offered to us in the states from 0 - 30 and 0 - 60. You seem to bring up the 30 - 50 numbers but the only place that has been posted is Toyota’s own press release and they didn’t even post a time to accomplish the task! I already know how slow the HCH and Insight are and I have made no bones about it. The dots you are failing to connect here is how efficient an Atkinson cycle ICE is (4% increase by most accounts with a > then 4% loss in torque).
Your car engine power and fuel economy estimates are way off as well.
___I post my fuel economy results on an ~ 10 day basis, how about you? As for power and efficiency, my numbers are way off? You not only missed that the HAH is supposedly capable of 38 mpg on the highway (not 32 like you thought) which does overtake the std. 240 HP ICE of the Accord V6 by a mere 26%. You also mentioned that the HAH will not be a SULEV? The 240 HP ICE of the Accord V6 is already a ULEV-II so it might yet still be SULEV rated when it arrives later on this year?
I am not going to zoom low down to your personal attacking level and pull out "your wife card" on you because you can beat me with experience. Delete msg#22 or I am going to ask a moderator to do so
___You just did and no. If you believe your particular choice of automobile is so efficient, take the challenge.
___Djasonw:
why don't you and I take a drive out to Illinois. We'll take my Prius and go there in "style". LOL!
When we get there, we can even have Wayne ride on Prius making total of 3 ppl. How would three of us fit in his Insight to do the comparison, unless Wayne wants to ride in the trunk?
___Don’t you live in NY? With your hybrid driving skills, you probably couldn’t make it across Ohio before running out of gas. So much for your “At least with the Prius you not only get great mileage” statement when Corolla drivers are surpassing your personal best(s) I will be more then happy to take your new Prius away from you if you are interested in the challenge of this Insighter and I will allow you the same extra 500 miles :-) And with the Corolla, I know it fits 4 and has received better fuel economy and range then you have ever seen so far. Maybe you need to learn to drive a bit better because you are having problems in the fuel economy area by the sounds of your mileage you have discussed to date.
Dennis..we'll have to make the trip in early Fall.
__Your on! Title for title. I will throw in the Corolla for good measure just so you don’t feel that you lost your Prius II for something less then close to equal value
___Terry2hu:
It seems xcel doesn't seem to understand that this is a board for PRIUS owners to discuss their PRIUS, NOT Honda hybrids!
___Did you forgot to read the title of this thread? It is called “Hybrid Gas Mileage: Good? Bad? As Expected?”.
___Let us recap and bring the thread closer to its calling So far, the following applies as reported in the Real Hybrid Mileage Database:
20 of 37 HCH drivers that have reported their actual tank over tank data are exceeding combined EPA estimates or 54%.
4 of 10 Honda Insight drivers that have reported their tank over tank data are exceeding combined EPA estimates or 40%.
1 of 6 Prius I drivers that have reported their tank over tank data are exceeding combined EPA estimates or 16%.
4 of 55 Prius II drivers that have reported their tank over tank data are exceeding combined EPA estimates or 7%.
___Given the title of the thread, who is more likely to be satisfied with their mileage, the majority that are beating EPA estimates or the majority that are not? Fortunately, there will be more Prius II drivers exceeding the EPA combined estimates in the near future but as of this writing, I can see more dissatisfied Prius drivers then HCH drivers in regards to their particular Hybrid’s fuel economy from those posting their tank over tank data to date.
___Good Luck
___Wayne R. Gerdes
Since you are the one who wanted this challenge, you will pay for the expense and for my time. Explain in detail, how you want it to be with precise rules of engagement. If you accept it, I'll seriously think about it.
Dennis
I wouldn't want all those Corollas passing me in the left lane! Imagine this shmuck is knocking the fact that I am getting close to 50 MPG with average speeds of 75-80 MPH with 35 PSI fr and 33 rr. Can't do that will a Corolla. Maybe with an Insight, but I do get claustrophobic, hence my aversion to that toy.
YES.
85.7 MPG over 967 miles from a single tank of gas without filling. The red icon on the top left means that Prius had run out of gas. The next question is, can HCH do 85.7 MPG?
Dennis
Actually, anyone could. Just set the cruise control to 35mph and let the computer do all the work. ;-D Gerdes effort not required! HAHAHAHA
Dennis
In another word, HCH can not achieve 85.7 MPG at any speed. What is the ceiling for HCH and at what speed? That would be interesting to know.
"Didn't see your red icon"
You dont' see that red icon that is covering the "C" of Comsumption?
Dennis
There are no data. That's the whole point. No HCH has gotten 85.7 MPG at any speed. Maybe someone can find out the ceiling of HCH. The best candidate would be Mr.Gerdes.
"No, I only see a blank unlinked picture box in IE or Netscape. Might be the firewall."
Anyone see the picture? I can definately see it. If not, all my efforts of posting all the pictures are just a waste!
Dennis
"the speed-torque characteristic of a typical electric motor is complementary to that of a high output gasoline engine". So with that in mind what do these geniuses do? Why, they conveniently slap a motor on the side of the 4 cyl and call it "integrated". And you can cover me with mustard and call me Hotdog too, but when the electric motor is only 10kw that makes about as much sense as for the WWF to pair Danny DeVito and Arnie Schwarzenegger as a wrestling tag team. What they should have done was take a planetary box with a 2.5:1 ratio, drive the planetary carrier a la Prius and connect the sun gear to the electric motor. This would have yielded a generous 90 ft-lbs instead of 36 ft-lbs. Two problems now arise 1. when engine does 6000 the motor will be doing 15000 but then GM's EV1 motor did 11900 (75mph )and it was 10 times larger. 2. Back EMF will cause (at higher revs) uncontrolled overvolting of the HV bus. [Body diodes become 3-phase full wave rectifier]. The solution is not to use a fixed field machine, remove those neodynium high energy magnets from the rotor and revert to a rotor excitation winding fed from slip rings (a more expensive solution) but you can now reduce the excitation at high revs and maintain full power from this motor over the full speed range. The increased torque during acceleration would allow the use of a smaller capacity engine. The 10 second burst of current would have to be within the discharge capability of the HV battery which may be Power limited. So I guess I am saying that there is not going to be a lot of difference between a Hybrid and a nonHybrid Honda as things stand, What you are getting is an Atkinised engine of lower performance which naturally is giving better mileage. If I went Honda I would buy the nonhybrid and keep myself from pressing hard on the loud pedal if I wanted to save gas.
1) "Hybrids running independently": Counter-example: Insight
2) "Rational economy(cost of car-fuel savings)": Counter-example: Accord/Camry
3) "Fuel economy": Counter-example: HCH
4) "Larger Size": Counter-example: Focus
5) "More seats than the Insight": Counter-example: Corolla, Accord etc (with a European car thrown in too!)
Yes! Exactly! What most of us (Prius 04) owners love about this car is the whole package: Great fuel economy, low emissions, roomy, greatly enhanced functionality from the hatchback design, plenty of additional safety features/techno-wizardry (VSC, side/curtain airbags/SS/SE etc), Toyota reliability, 7 year track record for the technology, comfortable ride, reasonable handling and acceleration. Sure, you can find cars that "beat" the Prius on any one of these features but we bought ours for the "whole package" and it is outstanding in that regard.
As for mileage, I am now over 50 mpg (per tank) regularly. This surprises me since my commute is only 5 miles long - not the ideal distance to demonstrate the true mpg of any car. From looking at this and other sites it does appear that most recent posts report MPG's at and over 50 mpg. For those considering purchasing this vehicle to use in a cold weather climate (Northeast Ohio for me), I think it is reasonable to expect mpg's averaging over 50 mpg for 7 months per year, dropping down to mid 40's for 5 months per year. Of course, this will vary a few mpg up or down depending on your commute (most important in my opinion), driving styles, tire PSI's etc.
I did not mean to offend you. I said "IF" you are. If not, then fine. I posted explanation so other readers might find useful. That's all.
HSD transformed and simplified the whole car by removing reduntant parts and consolidated most of the jobs into one primary part of the hybrid drivetrain. That part is hybrid transaxle.
A car is a very complex piece of machineary. To understand how HSD transform the whole car is not easy. It would not be right to say that Power Split Device is too complex because it is not. It has six moving parts permently connected with ball bearings.
To achieve the highest MPG/fuel economy, one will need to understand how each hybrid design is different.
"What they should have done was take a planetary box with a 2.5:1 ratio, drive the planetary carrier a la Prius and connect the sun gear to the electric motor"
I am confuse if you are suggesting a change for HCH or Prius. Prius PSD has 2:1 ratio for sun:planet gear. When the ICE is at 5,000 RPM, MG1 is at 10,000 RPM when the ring gear is at rest.
"The 10 second burst of current would have to be within the discharge capability of the HV battery which may be Power limited."
Prius' battery pack is 1.5kWH. If 50kW MG2 were to give 295 lbs-ft torque boost, the battery can last 90 seconds. But then battery ECU would not let the battery drain below 40% SOC, so the driver has 54 seconds of electric supercharger, assuming the battery has 100% SOC to begin with. If the battery has 80% SOC, the driver will still have 36 seconds.
Dennis
It is called Hybrid Transaxle. It is the size of traditional transmission but contains much more functionality such as electronically controlled CVT, electric motors to drive the car, generators capable of recapturing at least 80kW(not 10kW like HCH) of energy, acts as flywheel, replaces ICE starter and alternator, and many more!
Hybrid Transaxle "slap" between ICE and wheels like a transmission would. This is what Nissan will buy from Toyota among other things for Altima Hybrid.
"All that technical jargon still doesn't explain why HCH gets about the same MPG as Prius as reported by its owners."
Please remove your filtered glasses which makes you see only what you want to see. I just met a fellow during Tuesday chat with brand new HCH CVT. He is getting 36mpg and it is summer, not winter now. Most of the low Prius mpg you read in the news are winter before broken in.
"If HSD's refined, sensible more complicated system is "far superior" to Honda's simpler "Slapped and bolted" then why the about the same MPG?"
Prius is one class higher than HCH, faster acceleration in most(if not all) situations, gets higher MPG, longer battery warrenty, and many others that djasonw listed.
"show us where HSD beats IMA in MPG...not by 1 or 2 MPG but by 10 or 20MPG"
Compact cars are already very fuel efficient. When a faster and more responsive mid-size car beat a compact car in fuel economy, it means a lot. The difference will get greater when comparing with much larger hybrids between HSD and IMA!
Dennis
This device splits ICE's 72% torque to the wheel and 28% to the generator. The amount of horsepower that split is controlled electronically. Note that horsepower is a function of torque.
Dennis
It's simple, the more a hybrid can rely on electricity, the more gasoline a hybrid will save.
"What is the 0-30 and 0-30 specifications for Prius- I haven't located any."
Prius' 0-60 is about 10 seconds. According to Car And Driver magazine, Prius' 30-50 is 5.5 seconds. It will be safe to say that Prius' 0-30 is around 4 seconds.
"We both know our cars aren't rockets."
I was surprised that HCH didn't make it to Consumer Report family car comparison test due to the performance issues but Prius did.
Dennis
I see USBSEAWOLF2000 has put up the Prius transaxle. You can see that neither of its two motors is constrained to run at the speed of the engine so they can work together to force optimal torque from the engine. Is that a good thing ? Yes, its a very good thing. This is only my third post this year, let's hope my technical writing will get better. Time for some math. Honda says their motor produces 36 lbs-ft @1000RPM but this is only represents 5.1 KW By extrapolation we can probably expect the full 10kw @2000RPM. Considering that the engine is barely producing torque at 1000RPM shouldn't the motor be producing 10kw here. You would think so because by the time the engine gets to 2000RPM that 1.3 litre will be starting to bite. And any power at all from the electric motor will start to become increasingly insignificant and less relevant as the torque from the engine rapidly ramps towards 87 lbs-ft as the engine gathers speed. Beyond 2000 RPM the electric motor torque will drop inversely with speed (because at full voltage the electronic controller will sit in current limit and supply constant power). In my previous post I alerted you to the fact that the motor was incorrectly geared and should be turning at least twice as fast as the engine so that it could deliver power to the system lower down the torque curve. I suggested that the mismatch was akin to pairing Arnie and DiVito as tag team wrestlers. It was meant to be humurous; clearly I was being too obtuse. But you can appreciate that 10Kw from 1000 to 2000 rpm could be useful. It would appear as 72 lbs-ft initially fading to 36 LBS-ft at 2000rpm in the area where the engine is weakest. But that would require the insertion of a 2:1 step up gear of course. Finally going back to that Honda website, did any one notice from their figures that at 3000Rpm the IMA provided only 18lbs-ft of torque? Get your calculator and and see that that works out to be 7.67kw. Where did the 10KW go ? Well that's exactly the problem when you use fixed field machines at high speed, it gets harder to force current in against the back EMF of the motor. I suggested the use of variable excitation to overcome that. It's probably not worth it for an extra 4lbs-ft of torque. But you could get a lot more than 4lbs-ft if you really cared enough. I am not going to speculate how much that's for the after market tuners to decide. THNX to USBSEAWOLF2000 and Misterme, I'm done.
Anyway, just test drove an 04 Prius. My old man has ordered an 05 which he should be getting in late September or early October. This car is awesome. From the smart entry to the xenon head lamps and DVD navigation system, I think the $24G price tag is a bargain. I loved the near silent ride when the car is running on battery alone. Acceleration actually felt better than a Corolla or 4 cylinder Camry. Both my dad and I test drove the car and needless to say, we were both impressed. We couldn't drive the car for too long since it was someone else's pre ordered car. The salesman, whom my dad knows for a longtime really did us a favor.
Did you use "Enter" to skip a line? I notice the board deletes extra "Spaces"
"If you could take a minute and go over to the Hybrid Honda Accord 2005 forum and look at that impressive post #193 USBSEAWOLF2000 prepared, you will find a color image of the HCH engine/transaxle."
I just found out that Prius's MG1 is at least 30kW, possibly 35kW.
"Beyond 2000 RPM the electric motor torque will drop inversely with speed "
If you want to see it visually, take a look at the graph.
"It would appear as (HCH's IMA) 72 lbs-ft initially fading to 36 LBS-ft at 2000rpm in the area where the engine is weakest. But that would require the insertion of a 2:1 step up gear of course."
We know Honda's IMA to ICE is 1:1, meaning engine RPM turns exactly at the same rate as the 10kW electric motor. There is no transmission between ICE and 10kW electric motor.
For Prius, PSD enables three way CVT. It means ICE RPM and electric motors RPM can continuously vary to combine maximum output from gas and electric drivetrains. ICE, 30kW MG1 and 50kW MG2 ratio can vary at any time to maximize efficiency and fuel economy. All of this is made possible by a Pepsi can size PSD!
I've pointed this out many times but no one seems to understand.
Dennis
In a nutshell what I was suggesting was moving the electric motor base speed down from 2000rpm to 1000 rpm artificially with the aid of a 2:1 reduction. In case you may not be familiar with the term "base speed".
Base Speed is the lowest speed at which the motor can deliver full rated power.
I was assuming that Honda wanted to assist the engine where it was weakest i.e. at 1000 rpm.
So to connect a motor of 2000 rpm base speed -no one disputes this value do they ? - directly to it means that you only get the benefit of 5kw of power. Not the 10kw that you might have expected from the hype surrounding this vehicle. I call that a mismatch -an error.
A financial tradeoff against the cost of coupling it separately on to the engine crankshaft via a 2:1 reduction gearbox.
Without a gearbox, the only way they could get get 10kw power at 1000rpm would be to stretch the motor from its current 65mm thickness to 130mm. This goes with the general theory of machines that low base speed machines are always of larger frame size. There is no free lunch if you want to directly connect an electric motor to the crankshaft.
And that, as we know, is what they did.
Analyzing the IMA system
We get at 2000rpm the rated 10kw while still pumping out 36lbs-ft.
But then at 3000rpm it has dropped to 18lbs-ft (Honda's figures)
If it was having no problems shouldn't this figure be 24lbs-ft !!! I don't know, you tell me.
Clearly the controller being presented with higher frequencies and higher motor back EMF has run out of "headroom on the bus voltage" and is no longer able to supply the current needed.
The transistors can put out the right frequency ok but it seems they've lost control of the current which is now being determined by the physical attributes of the system viz inductance and back EMF.
And if it is 6lbs-ft lower than expected at 3000 rpm .......
Any guesses what the Integrated Motor Assist might be assisting at when the engine reaches a full bore acceleration at 5700rpm ? 2lbs-ft perhaps ?
I don't know about you but that to me is one lame system. I would be happy to hear a rebuttal from genuine Honda fans. No salesman tirades thankyou very much.
Why doesn't the Prius '04 have this problem particularly now they are using the lower 201v HV battery pack. Well, they headed it off by incorporating a seamless 500 volt up converter which gets energised before the inverters run into a voltage headroom shortage. Knocking the volts up will keep the inverters in control.
Dennis any other issue ?
Finally I hope tech talk won't scare anyone away who wants to post fuel consumption etc. Can't beat hands on experience. I believe that driving style and temperature are the largest factors affecting fuel consumption but knowing about your vehicle's system can be of help. For instance with the Honda Civic the above tech talk reveals that the IMA is fairly ineffective if the engine goes above 3000 rpm while accelerating.
In closing, I must mention that on insightman's site he's put out an interesting fluff piece on Fuelorexia nervosa, you might wanna see.