- Despite promises that the Chevy Volt will operate as an electric car at all times, it will in fact at times be directly driven in part by its internal combustion engine.
- The mechanical link between Ecotec internal combustion engine and drive wheels will be at high speed.
DETROIT — It's the big headline currently on GM's media news site:
Um, well, no. Even conceding that all engineering projects involve compromise and chalking that phrase up to marketing hyperbole, the Chevy Volt isn't as electric as GM pretends it is. And it isn't as electric as GM has been saying for the past three years. You know, GM statements like this one:
In fact the Chevy Volt is a plug-in hybrid and it has more in common with conventional "series-parallel" hybrids like the Toyota Prius than the marketing hype led us to believe. There are circumstances in which the Volt operates with the internal combustion engine directly driving the front wheels. That's right, like a Prius.
At the heart of the Volt is the "Voltec" propulsion system and the heart of Voltec is the "4ET50" electric drive unit that contains a pair of electric motors and a "multi-mode transaxle with continuously variable capacity." This is how GM describes it:
The 4ET50 is, however, in fact directly bolted to the 1.4-liter, four-cylinder Ecotec internal combustion engine. When the Volt's lithium-ion battery pack runs down, clutches in the 4ET50 engage and the Ecotec engine is lashed to the generator to produce the electric power necessary to drive the car. However, under certain circumstances — speeds near or above 70 mph — the engine will directly drive the front wheels in conjunction with the electric motors.
As in the Prius, the Volt's drivetrain includes a planetary gear set that acts as a transmission. The intricacies of planetary gears are many, but in rough terms each element (electric engines and internal combustion engine) of the Prius or Volt drivetrains are hooked up to different elements of the gear set. In the Volt, its Ecotec engine is clutched to the outer ring gear and as the car's speed reaches the edge of efficiency for the electric motor, that ring is set from its normally rigid mounting in the 4ET50's case and allowed to spin. That has the Ecotec driving the front wheels.
The Volt's Vehicle Line Executive Doug Parks confirmed that there is, on occasion, a mechanical connection between the internal combustion engine and drive wheels in an interview with Norman Mayersohn of The New York Times. This isn't idle speculation or educated inference; it's an admitted fact.
What's vexing here is that GM hasn't been forthright in explaining this. It's not like this sort of operation isn't an integral part of the Volt's drivetrain — the engineering team has to have known this is how the car would work for a while now. But even today, GM's press releases and consumer information insist that the Volt is always and solely electrically driven. That's simply not true.
Frankly, we were lied to. Back in June, John O'Dell who edits Edmunds.com's eco-obsessed sister site The Green Car Advisor reported on rumors that last minute revisions would have the Volt using a direct mechanical connection between its Ecotec engine and drive wheels. So O'Dell asked GM's spokesman Robert Petersen directly if the rumors were true. Petersen clearly denied the rumors and insisted the Volt (and its European brother the Opel Ampera) would be driven solely by electricity.
Inside Line says: Don't believe everything GM says. No matter how many times they say it.— John Pearley Huffman, Correspondent
Add A Comment »
owlafaye says:
08:41 PM, 10/25/2010
mfennell is a thinking engineer...good post.
General public knowledge regarding power transfer losses is minimal. I am simply amazed that GM engineers didn't simply balk when the powers that be proposed the VOLT...whoever gave them the blueprint apparently hates job/people/past at GM.
VOLT is one of the silliest most complicated automotive ideas in history. I believe the Owens Magnetic did a much better job back in 1919 or so. Ask Jay Leno, he has one.
Folks here are correct in that GM is destined for another bankruptcy.
owlafaye says:
08:29 PM, 10/25/2010
The VOLT concept is now over 1400 days old and the design has changed numerous times.
A conventional automobile has:
1- An engine driving the wheels
VOLT has:
1- An engine driving a generator
2- A generator driving a motor(s)
3- Motor(s) driving the wheels
TWO additional POWER TRANSFER LOSSES !!!
In electric mode, the VOLT runs on pure battery supplied electricity...but only for 40 miles! Then the engine kicks in and supposedly runs at constant speed as it drives the generator and the motors simultaneously. At higher speeds, where more power is needed, the engine also drives the wheels through a ring gear set.
Sound complicated? It is VERY complicated. The engineers at GM are in this very deep and they have constantly re-designed the many, various and complicated options without getting satisfactory overall mileage or longevity.
The VOLT will be plagued with problems and will prove to be incapable of delivering on any of its promises. This is a modern day EDSEL destined for ridicule and ultimate failure.
MARK MY WORD ! 10/25/2010
drkhorse35 says:
11:28 PM, 10/24/2010
For seppo57, voltfan, and all you other 'GM can do no wrong' people out there, you are about to get your bubble burst. Did you not read the full Edmund's article? If so, let me refresh your memory with three little tidbits from it, actually recent quotes from GM press releases, statements, and publications: "2011 Chevrolet Volt Reinvents Automotive Transportation In A Complete No Compromises Electric Package"; "The Chevrolet Volt is not a hybrid. It is a one-of-a-kind, all-electrically driven vehicle designed and engineered to operate in all climates."; "Unlike a conventional powertrain, there are no step gears within the unit, and no direct mechanical linkage from the engine, through the drive unit to the wheels."
Well boys and girls those three quotes are at the very least patently misleading, if not downright lies that GM has perpetrated on the consuming public. Let me be clear, I do think that GM currently builds some great vehicles, and I hope that they, as well as Ford and Chysler, succeed. But I don't appreciate being misled and downright lied to concerning the capabilities of a product! Don't get me wrong, I do believe that having the gas motor as a range extender is an excellent idea and the only way to go right now until we get pure electrics with 300-400 mile ranges, but don't lie to me about the use of that motor GM!
Yes, Popular Mechanix did name the Volt as a "Top Pick", but they call it a PLUG-IN SERIES HYBRID, and the range/mpg numbers PM got were not flattering. PM measured the EV range for three different modes of driving and it averaged 33 miles, about 17.5% below what GM advertises. PM also measured the "charge sustaining"(i.e. extended range) mode which uses the gas engine to drive the front wheels at/above 70 mph or when the battery pack is depleted and, including the EV range, got a best of 37.5 mpg city and 38.15 mpg hwy. That's not quite the "230 mpg city" that the prior GM CEO Fritz Henderson stated the Volt would get! To answer qdp's question about why those mpg numbers are so low you might consider the 3700+ pounds curb weight, as much as the old rear drive full size Chevy Impalas of the 60's!.
Then there is the cost? One of the ealier bloggers stated you can drive 40 miles and not cost you anything. What, is electricity free where you people are from? The Volt lists for over $41K, about 44% more than a basic Prius, and gets about 17.5% worse combined city/hwy mileage than the Prius. PM also stated that the interior component quality was not up to par.
Mind you, I personally wouldn't buy a Toyota but if someone who was dead-set on buying an electric type vehicle that was actually usable asked me, depending on their needs I might recommend the Ford Fusion or Escape (both can attain up to 41mph on electric only)or the Prius. I might even recommend the Leaf if they were gonna max out at say 50 miles per day. Right now I would not recommend the Volt because it's way too PRICEY!
digitalzombie says:
11:39 PM, 10/23/2010
LOL, yeah... I'll take the Prius then. They sorta misled me too. I thought the engine was powering the generators not the car.
I guess this post is going to take a lot of angry fan boys cause they're going to defend GM to the death.
With this new revelation the Volt is probably going to be a flop. I don't think the difference is big enough to buy this overprice hybrid over a prius. Sigh, come on GM!
haole says:
12:50 PM, 10/21/2010
So does this jeopordize its $7k tax rebate...I dont know what the qualifications were for that?
If this is the case then the Prius should qualify for the same $7k. It seems like its more similar than different than the Volt. And how do they know if most people will actually plug in every night or not becuase if they dont plug in then they will actually be getting worse gas milage than Prius drivers if the battery isnt charged.
I havent heard much about the plug in prius but im guessing it will be a lot cheaper than the volt depending on the battery packs they decide to go with.
hwyhobo says:
07:06 PM, 10/18/2010
Thank God someone at GM still has some braincells left and decided to build a more practical vehicle. Now let's wait till they drop the price by $15K, and they will have a winner...
seppo57 says:
06:04 PM, 10/17/2010
This article is a joke. There is one obvious criterion to figure out whether a car is an EV or a hybrid: Can you drive it normally on battery alone. The answer in the Volt is yes, the answer for the Prius is no (and by driving I mean actually using the accelerator - no special driving technique). The fact that the Volt does have an engine to extend its range might just be the feature that makes EVs palatable to a large audience. If, in range-extend mode, it is more efficient to couple the gas engine to the wheels directly at high speed, what's the big deal? Are you suggesting Chevy should pick an inferior option for cosmetic reasons?
I guess there is still a quality difference between Edmunds and professionals like Car & Driver and Motortrend: This is a blogging operation, the other two actually employ journalists...
voltfan says:
04:57 PM, 10/16/2010
The Chevy volt is a true electric driven car with a 4 cylinder internal combustion engine attached to a 55 kw generator that will supply electricity to the Volts battery to extend the driving range from the 40 miles charge range this is a true electric car that is driven by an electric drive motor there is no connection between the internal combustion generator to the drive train.
In the nissan leaf the range is supposed to be 100 miles If you feel that you need to travel more than the 100 mile range of the nissan leaf thats 50 miles out and then the return 50 miles less any electricity used to run the ac and other accessories your true range can be as low as 60 to 70 miles thats 30 miles out and 30 miles back the range is limited to your available charge.
You can in the Volt. The Volts range isnt limited to the charge of the battery pack after the battery is depleated to 20% of it charge the generator will turn on and produce electricity to supply the battery and electric drive motor and extend your range way beyond that of the nissan leaf after the Volt hits the market all of the bad hype will disapear it will be better than the prius or nissan leaf.
1919diesel says:
01:50 PM, 10/15/2010
IL, go get into your Nissan Leaf and cry all the way home!
Oh yeah, that's right, you won't make it all the way home because your Leaf ran out of charge, since you decided to run an errand on the way, or you ran the A/C or the Heat and it was cold or hot outside, and you were driving faster than 55 MPH on the highway,.... in other words, you drove the golf-cart like you would a normal car, and it's batteries ran out of juice, so now maybe someone in a Volt will stop and give you a lift to the nearest gas station so you can fill up your gas can... oh yeah, that's right, you need a really really really really really long extension cord so you can plug into that handy dandy non-existent charging station at the next exit. Or else you need a tow truck (with a GAS or DIESEL engine) to haul your cutesy leaf home to tuck in, I mean plug in at night..............
bodyblue says:
08:33 AM, 10/15/2010
"Your inability to understand that everyone who disagrees with you is not a plant no doubt calls your motives into question for many."
I completely understand that not everybody is a professional blogger. But there are some plants on here, and if you say you are not then I belive you. My motives, as you call them, are to find liars and plants...they are easy to spot and fun to expose. They easily turn the thread into a political one (one of the reasonse I put some political comments out there was to bait them into it) AND every single one had the same views.....what a surprise! The blogosphere is full of professional bloggers who join sites when told to for the purpose of pushing an agenda....both left or right. This time it was the UAW and their ilk. They show up for a few days and agitate then they are gone. Then there are folks like 1487 which defy description. He defends GM to the death and no one on here can figure out why. Everybody has a different opinion and has a right to talk about it. The way they present such opinion defines what kind of person they are. I was hot and over the top on this thread because of how heated it became. I hate liars and dishonest posters more than anything and will never stop pointing them out. Hope that helps you understand better.