Discussion in 'In the News' started by xcel, Oct 5, 2012.
Edited because it won't let me delete it.
This is the same behavior I see in my wife's first generation FFH above 34mph. My guess is that it is spinning the engine (with no fuel) to keep from exceeding the electric motor RPM limits. This is what the Prius does for "Warp Stealth" and also what one of the PHEV conversion kits for the Prius II does to allow higher (highway) speed EV only driving.
Why is the car charging the battery and then shutting off the engine at highway speeds? It will suffer unnecessary conversion losses, true?
Seems to me if you are asking for more-or-less constant power at highway speeds (DWL), the most efficient thing for the car to do would be to keep the ICE on and drive the wheels directly like the Prius does. If you are P&Ging that's a different story, of course, but it sounds like rmcmast is doing more DWL.
Could it be that the C-Max does better on the EPA tests because there is very little constant speed, but a lot of speed changes? It could be making hay on those speed changes through electronic P&G of sorts.
Doesn't make sense to me intuitively, but perhaps?
Thanks, I may have been using the term "gliding" incorrectly. I was referring to coasting while still in Drive. I noticed early on that there was some battery drain with the C-Max anytime gliding in N which was the same in my 2009 FEH. In the FEH I could highspeed coast or glide with fuel cut. I probably need to start using glides in N if I have quite a bit of charge in the battery.
I got 48.3mpg on the drive to work today (28 miles). Traffic was light so I could let speed bleed off climbing hills and coast down in EV. 55° OAT.
Why would spinning the engine draw current from the big pack? Couldn't the power electronics shut off current between the e-motor and the pack while coasting in neutral?
CRT1 -- Hybid Candy--excessive use of EV. My hunch is something like that is the game the Ford Engineers played to get the inflated EPA figures. It's not that they lied or the car isn't capable of producing those numbers, it's that knowing the test's protocols they set up the car for optimal performance on the test, which at the worst may impede the owner's ability to max MPG in the real world (ie big conversion losses, loss of true gliding/coasting). At the very least, it's cynically deceptive marketing.
That being said, I think it's the perfect car for my parents and there is a slight chance we'll buy one for the business--more likely the V because of its larger cargo area.
AATG, I'm not sure what the Prius does for warp neutral but Ford ECVT implementations do not appear to have a true "disconnected" neutral state. The RPM limits are for the bearings in the motors and when the Prius does this trick it spins the engine with the pack to avoid having those motors exceed specifications (because this is a 3 input system with the "gear ratio" determined by the speeds of all three inputs). There is an excellent descriptive analysis of this mechanism at the link below from Hobbit:
Sean, That could be it. What seems to be happening though is it's always pulling a charge even at slower speeds.
Thanks Sean -- I didn't realize it was the battery spinnig the motor.
Drive to work, half freeway. 41.1 mpg. Drive home, no freeway but some 55 mph. 50.9 mpg. If only I wasn't always in a hurry in the morning. From now on I will post in the C-MAX forum unless we want to keep using this one.
Re : Ford’s Goofy C-MAX Hybrid Commercial
Hello all: I have driven the c-max two more times since the last post and here are the results... Yesterday I went out on MA 146 for another round trip test. Temperatures were 61 degrees and I kept the speed right at 65mph. Mile marker to mile marker round trip I only achieved 36mph. I then reset the indicator as I exited the freeway. I managed 61mpg on the 5 mile or so trip back on 30-45mph surface roads. Moments later I hopped into a 2012 Fusion hybrid with about 11k miles on it. I did the exact same drives and got virtually the exact same numbers. Interesting to note is that the cmax is rated at 47 across the board and the 2012 ffh is rated at 41 city and 36 hwy. The FFH achieved its hwy rating at 65mph. The C-max fell way short. I then did the exact same drive in my 2005 prius moments later with 321k miles on the clock and original batteries. I pulled 50mpg at 65mph mile marker to mile marker and an indicated 87mpg for the surface roads from the freeway exit back to the dealership. It looks like Ford is in some serious trouble...
The sales guy was very nice but tried to suggest that it take 2,000 miles until an American car hits its epa. He claims the seals need to adjust. I know that this is bull&%^#. The sales manager agreed with my but tried to claim the Afcd may be off. I know that is BS as well. They know they are screwed they just do not want to admit it yet...
Today I drove yet another c-max, this time on I 495 near Franklin MA. The same round trip tests yielded again 36mpg at 65mph and this time the temps were 66 degrees. Terrain was a bit more level than MA 146. I was originally considering the c-max a potential replacement for my 2008 Nissan Altima hybrid but not anymore. I believe the c-max is a nice vehicle but I am very dissapointed in the fuel economy. There will soon be a lot of ticked off owners and I hope the word gets out so people will not make a 26k-30k mistake. More info after the next test drive.
I'd ask the sales critter why suggest that it take 2000 miles until an American car hits its epa yet the C-Max manual says 1000 - I would say 500 should do it
Wow, this is really shocking. Not sure how it gets such terrible FE at steady-state speeds on the highway. It must have bad aero. Did Ford release a Cd? Thanks for the report.
I'm still considering the Energi because I could do probably 80% all-electric and probably only do 5% of my miles on the highway using the ICE.
Right then, if it cannot best my '99 Elantra out on the highway, it's sure as heck not coming home to my driveway . I truly hope Hyundai shoves their hybrid drive into their smaller lineup. In any case, I still have about 3-4 years before I move out of my current Prius, so it'll be interesting to see what happens here in the next two years.
The Ford C-MAX hybrids Cd = .30
That's not too good, combined with more frontal area compared to a Prius or FIT. Do you think this is the whole story?
While aero would have an effect, the 55 mph steady state numbers should easily blast out its EPA highway and Jesse's drive are showing that is not quite in the cards. I am not sure although the Ford calibration engineers are the best in the business when it comes to hybrids.
I am eager to perform a top off to top off calibrated run and then the steady states to generate a Speed vs. FE curve if only to satisfy my own curiosity.
Here's a 7 mile test drive comparison.
1. Salesman drove the first 1.5 miles: net down hill so my drive back to the dealership was net up hill -- have to tell him to stop that.
2. C-Max started cold and spent much of the above in EV mode so the engine was only slightly warm when I started.
3. HCH2 engine was warm: sat for approximately half an hour then covered the 1.5 miles to the start of the test.
4. HCH2 tires 56psi -- 50% grill block. C-Max stock and active shutters.
5. C-Max started 50% SOC--dropped to 25% started forced charge last 1/4 mile.
6. HCH2 SOC: no change -- SOC has been persistently high this week .
7. 58f -- windy
8. 30-45 mph stoplight strung roads + a last 3 mile uphill stretch of 55 state hwy.
9. When I did a Prius V back to back my HCH2 only beat it by a few MPG's and it had the better trip.
10. A good amount of neutral glide in the C-Max -- seemed to coast better that way then any position I could find with my right foot.
47.7 mpg indicated - acutal ? - 7 miles - 54mpg peak - 453 miles total - 33mpg indicated .
58.7 indicated - 60.4 actual - 62mpg peak
Trip home from the dealership -- it was a good day.
66.4 indicated - 68.1 actual.
C-Max is an EV wanna be -- too much hybrid candy -- lots of energy conversion losses and the engine has a hard time staying warm due to the excessive EV use--it's thirsty when it starts. It's an Atkinson cycle engine, with all of the claimed advancements in Ford's varible valve timiming you'd think that it would have a low RPM gas sipping mode for holding steady state / dwl, but instead it burns battery juice.
Absolutely love everything else about it...maybe the Energi will be the star???
Thanks for the report AATG. It is curious from your report and others that the car is tuned to do a charge and EV glide. This can be advantageous under some circumstances but it is costly as you point out due to conversion losses if used to much. Is there an EV button on this car that allows you to choose when to glide by shutting off the ICE? Do you think this would yield improved results?
Great report! Do you remember what the Prius v achieved on your back to back vs. your HCH-II?
I was just on the phone with Bob Winger who is heading out to possibly purchase a C-MAX or even put $'s down on an Energi this weekend. I told him my thoughts about the interior, the cargo cap, the actual mpg buyers may expect all up against the Prius and Prius v and for him and his wife to go into this purchase with their eyes wide open.
It needs at least three changes with a least two selectable modes:
1. True soft-glide / stealth mode under the 62mph EV limit: no gas, no battery drain.
2. A gas sipping super highway/steady-state timing set-up for the ICE -- maybe it has one and I couldn't find it in my short drive or perhaps the engine never got hot enough??
3. A mode to make (2) the default low rpm state rather than the current EV mode.
Leaving the shaky battery issue asside -- I'll take Honda's IMA system anyday.
The brochure highlights the in EV mode stating something to the effect that the ICE only comes on to sustain the charge or to add power. The salesman said essentially the same thing...it must be a feature they are advertising.
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