Clarification: Gas Engine Can Help Drive the Volt Starting at 30 MPH

[pow]

As regular readers here know, I have faithfully followed every detail of the Chevrolet Volt story and every morsel of news since the car was no more than a show car shell and a pen and paper idea.

Over these months and years we’ve run into many controversial moments.

Perhaps none has been as controversial as the present “gas engine driving the wheels” fiasco.

Earlier this week I attended GM’s first media press conference where executive engineer Larry Nitz described how the Volt operated. In the lecture he specifically mentioned 70 MPH as the point where the combustion engine can contribute power indirectly to the driveshaft. He was quite specific this can only occur once the vehilce is in extended range mode.

I reported this information in great detail here in a post called Chevrolet Volt Electric Propuslion System Unveiled.

Soon after, news started coming out suggesting the engine can help drive the car at even lower velocities. I sent a note to Mr. Nitz, and spokesperson Rob Peterson responded:

The engine WILL NOT turn on while the car is in electric driving mode (which for your trip two days ago approached 50 miles) – simply put, it is a full-performance battery electric vehicle.

Once the battery is depleted, the Volt’s gas-powered engine engages to create the power needed to extend the range of the vehicle several hundred additional miles. In extended range mode the Volt is powered by either a 1-motor series or 2-motor combined mode. The vehicle will select the most efficient mode for the driving condition: 1-motor series – for operations almost exclusively below 30 mph; 2-motor combined almost exclusively above 70 mph. At speeds in between 30-70 mph, the Volt will select the most optimally efficient drive mode amongst the two.

So it turns out the engine can contribute motive force to the Volt even at speeds from 30 to 70 mph presumably when the power demand calls for it such as hills and strong acceleration. Perhaps even more than that, Peterson wouldn’t say.

Volt chief engineer Andrew Farah explained this a bit more in an interview.

“The 70 mile an hour thing, we’re really not sure where that came from,” he said. “Somebody didn’t get the story right.”

He said there were specific determinants when the engine would provide input to the driveshaft. “Its’ really more an issue of torque and power than it is of speed,” he said.

The Volt has internal programming to determine at what points the engine should be coupled in. “It has an efficiency map, and based on the efficiency map it will decide what to do,” said Farah.

The gear-heads among us, myself included, want to know exactly how the Volt works, and for that reason these details are important. In the big scheme of things, though, and to most consumers, it really doesn’t matter. The car will carry you for 40 miles without gas. That’s the promise.

After that it becomes a hybrid. It is actually the reverse of current hybrids like the Prius in that in the Volt the electric motor is the main player, and the gas engine is the minor assistant. In most of today’s hybrids the opposite is true. This allows the Volt to have the unmistakable feel of pure electric drive in all circumstances. To that I can fully attest.

Do I feel GM lied to me as some whiny journalist have claimed? No. Lying is too strong a term. It was more of a corporate decision to conceal these details until an appropriate time to keep a competitive edge.

I don’t feel betrayed, or frankly really care at all. And to all the journalists getting lit up about all this I’m really not sure what the fuss is all about..ruffled feathers?

What it is about is having the most people use the least oil as possible, without compromising their lifestyles in a car that’s good looking, high tech, and fun to drive. And to that mission the Volt holds true in a big way.

GM has done an amazing thing here despite all the odds against them, an for that I am extremely pleased that I have committed nearly four year of my life evangelizing this car. I should be getting my Volt in just 10 days, and I can’t wait.

So let us have a moment of silence and allow this controversy to die a natural death.

http://gm-volt.com/2010/10/15/clarification-gas-engine-can-help-drive-the-chevrolet-volt-starting-at-30-mph/

[hyperv6]

I think once these cars hit the road few people will car what does what when they see the results.

I just hope the recalls and problems are few. I fear what these media types will do with even a simple recall.

You can see the misinformation that come out in a election throught the media so what is to stop them from trashing companies and cars.

Toyota, Nissan and Honda are in fear of this car. It can scap all thier plans and money spent on their own plug ins.

I can't wait to hear how life with your car goes. you need to start a log here has let us know how daily life is with this car.

Edited October 15, 2010 by hyperv6

[Drew Dowdell]

Well, that's not what the Volt's powertrain chief engineer told me and that's not what the presentation GM gave said.

The statement was that the second motor was used above 70mph because running the primary motor above 6000 rpm was energy inefficient. If you're not above 70mph, then the efficiency issue isn't there.

I'm not disputing what's in this post really, but just watch your own presentation GM, that's where it came from.

[GXT]

Well, that's not what the Volt's powertrain chief engineer told me and that's not what the presentation GM gave said.

The statement was that the second motor was used above 70mph because running the primary motor above 6000 rpm was energy inefficient. If you're not above 70mph, then the efficiency issue isn't there.

I'm not disputing what's in this post really, but just watch your own presentation GM, that's where it came from.

The inefficiency issue would exist whenever the Volt is on the ICE and the ICE isn't assisting. At the risk of once again being labelled a TROLL, as I have been saying for years, the ICE driving the wheels will tend to be more efficient than the ICE generating elec to drive the motor. It appears to just be that much worse over 70 because of the way the volt's "transmission" works. That's why it makes sense to drive the wheels with the ICE even under 70. And that is yet another reason why the Prius is more efficient on the ICE.

Go figure that after years of GM misleading (if not lying... but I won't go there) about this issue that there is confusion now. However I think the real reason that there is confusion is because GM is still doing their best to minimize/gloss over this issue.