GM-VOLT : Chevy Volt Electric Car Site

The two most closely guarded secrets about the Chevrolet Volt have been its price and its fuel economy while running in generator mode.

Now that we know the price, how about the other secret?

It turns out we may never see an official announcement from GM even after the car launches into retail deliveries.

GM has insisted, rightly so, the Volt should not be compared to other cars, and that its in a class of its own. Without doubt for the majority of drivers during the majority of their drives the Volt will use no gas at all. And although gas will burn at a certain rate while the generator is running, its contribution to overall fuel economy may be minimal.

When GM announced last Summer that the Volt could get 230 mpg on average over time, they took into account nightly recharging and typical driving patterns. It was an illustration but not fact.

The fact is the EPA is still trying to determine the best method for creating a consumer sticker for the Volt. Recently ratified SAE J1711 standard will be used to measure the car’s efficiency and still takes use over time into account.

Because the typically slow-moving bureaucratic EPA still hasn’t concluded what label the Volt will have, GM admits they might not even have one from them come November when the car reaches showrooms.

“Its possible the EPA still won’t have a label when the Volt goes into production,” said GM spokesperson Rob Peterson. “They’re just trying to do what’s right.”

Instead GM may issue its own detailed chart label to go with the car illustrating typical fuel usage in a variety of scenarios that will serve temporarily.

“The VOLT will have a label for launch with a lot of information to assist the customer,” says Volt vehicle line director Tony Posawatz. “It will not be the final label beyond 2011 MY.”

The eventual EPA label “will have a lot of info including a fuel efficiency number if you never charge your VOLT,” he said.

As for who will release that generator (CS) mode MPG, it “wont be GM,” said Peterson. We won’t then likely get fuel economy in generator mode estimates until the cars is driven for extended periods by early buyers and the media.

Recently there has been a lot of Internet controversey with at least a dozen articles covering a story out of the Telegraph in England. Of course, GM-Volt.com was the first to notice this claim and publish it, all the other sites followed.

The author, Andrew English, claimed the 65% calibration version Ampera/Volt prototype seemed to have a flat torque curve at high velocity. He wrote that an engineer claimed GM was planning to correct this by connecting the gas engine driectly to the drivetrain. I had checked in with Rob Peterson who said the claim was untrue and unfounded, and is not the case. Rob explained to us the Volt uses clutches and a planetary gear system to maximize performance and efficiency.

Despite this, English published a second report called “Volt Shock.”

In this repert he outed his source. “We are considering driving the wheels directly from the petrol engine,” said Andreas Voight, an Opel project engineer. There are a number of different ways we could do it, but the whole thing is subject to some intellectual property rights negotiations so I can’t say any more,” said Voight. “You will see an announcement this autumn.”

While that story may be shocking, it remains untrue. Sam Abuelsamid from Autobloggreen determined Voight is simply a technician whose job (?former) is to simply shuttle cars for journalists and who has no actual knowledge about Volt engineering. Know the type?

Another bad piece of journalism came out fo hybridcars.com, who won’t even publish authors’ names. The anonymous author claimed an “exclusive” interview with Rob Peterson. In that interview Peterson’s comments were taken out of context and distorted to make it seem the Volt would act like a parallel hybrid in range extended mode. Peterson was simply saying it was theoretically possible but the author left out the part where he said it wouldn’t. Anything is possible.

What many authors don’t know is that the Volt has two electric motors that can act either in parallel at times, in other cases one acts as the traction motor to drive the wheels and the other acts as a generator. The system uses 2-mode technology to determine which configuration is optimal for that driving moment. It never, however, includes a direct ICE to wheel configuration. For more deatils see my post with Volt powertrain engineer Alex Cattelan.

Finally to put this all to rest, I asked Volt vehicle line director Tony Posawatz if any of this rumor was true, if the ICE ever drives the wheels.

“No.” said Posawatz. “I don’t know how those folks got so confused.”

Got it?

When the Chevrolet Volt concept was first unveiled in January 2007 it illustrated the use of a 1-L 3-cylinder combustion engine.  Other variants of the Voltec propulsion system, then known as E-Flex, were also demonstrated at various times.  These included hydrogen fuel cell and diesel concepts.

In the end GM decided to go with a 1.4 L normally aspirated 4 cylinder engine that will also be used in other GM cars including the high volume Chevy Cruze expected to launch in the fall.

GM has apparently been continuing to study other possible range extenders, according to a report from Edmund’s, with the hope that one of these could make its way into the second generation of the car expected in the 2013-2014 timeframe.

One of the barriers to the Volt making it to high sales volumes is the considerable expense not only of the battery but of the complex extended range drivetrain, something pure EVs like the LEAF do not have to contend with.

“Right now, the propulsion system is too expensive, even with using an existing engine,” said GM’s new vice president of global vehicle engineering, Karl Stracke.

Stracke explained that GM is looking carefully at several different range extenders for future generations.  These systems include two cylinder gas engines, diesel engines, and even rotary or Wankel engines.

“We have a strategy to go rotary engines or a two-cylinder [gas] engine making 15-18 kW,” said Stracke.  ”Rotary has a higher fuel consumption but here’s the advantage [holds up his hands to form round, frisbee-sized shape] — packaging.”

Stracke has even piloted a rotary engine-powered Volt prototype.  ”I have driven the car already,” he said.

“One rotor could be enough,” he added. “Of course with the higher rpm of a rotary, you need to have an NVH solution.”

Stracke also believes a diesel powerplant could find its way into the Volt.  ”The cost of the engine would be higher for the manufacturer,” said Stracke of the diesel engine, “but the fuel costs would be cheaper for customers.”

To reach high volume sales, not only does GM have to lower the cost of the powertrain but also the cost of the battery pack.  And, for the first time in the history of GM-Volt.com a GM executive finally admitted the total cost of the Volt’s 16 kwh lithium-ion pack.

The pack costs “roughly $10,000,” said Stracke.  He also said that GM is “working aggressively to get that cost down 50 percent” for the next generation Volt.

“The future of the automobile has never been as interesting as it is right now,” said Stracke. “Big question is, what new propulsion system will come next?”

Source (Edmunds)

Many people who fancy buying and driving a Volt plan to use little or no gasoline.  Since the car will accommodate up to 80% of the population’s driving needs purely on electricity, GM has to prepare for an engine that may be rarely or never used.

A similar concern is the possibility of old gas becoming stale.

GM is using a pressurized zero evaporation gas tank to keep the gas fresh.

“It’s like shrink-wrapping your food,” engineer Trent Warnke told Ward’s Auto. “It keeps the fuel from aging.”

GM will also recommend low gas using consumers only fill their tanks halfway to prevent spoilage.

In addition, the car will have a special algorithm in its control software to ensure the gas engine runs at least once every 60 days to keep things circulating.

The engine will only run while the car is in motion, and will only do so for about 10 minutes. This is sufficient time for the control unit to perform some diagnostic checks as well.

Thus far, the 80 or so pre-production Volts have endured over 500,000 collective miles of test driving, with one car having completed 66,000 miles.

Starting in May, 300 more pre-production or validation vehicles will be built on the full-scale Detroit Hamtramck assembly line. These will be used for testing by engineers, consumers, and the media.

The first saleable car is scheduled to be built on November 1.

Peak all electric range occurs when driving between 45 and 50 mph.

Source (Ward’s Auto, subscription only)

With each passing day, week, and month the excitement builds as the Chevy Volt eases towards mass production later this year.

Earlier this month GM opened its dedicated battery assembly plant capable of producing enough packs to build tens of thousands of Chevy volt’s per year.

Another critical component of the car is its gas-engine range-extending generator.

The engine will be a 4 cylinder 1.4 L Ecotec powerplant, which will also be put to use in the Chevy Cruze. That car with a turbocharger is expected to acheve up to 40 MPG on the highway.

These engines will be built in Flint Michigan at a facility called Flint Engine South.

This week that plant began installing the equipment that will be used to build the engines, and will be ready to start mass prodution in about six months.

“We have a lot of work to do, but we’re getting there. We should be able to start running parts in July,” said Paul Matney a team leader on the production line.

Chevrolet Volt assembly will begin in Detroit-Hamtramck in March, so the inital three to four months of preproduction validation builds will have to reply on engines imported from Austria, until the Flint facility is fully up and running.

Old equipment is still currently being moved out and most of the new equipment has yet to arrive. The facility is currently producing the 3.6 L V-6 engines in use in the Buick Enclave, Chevrolet Traverse, GM Acadia and Cadillac CTS.

“Our goal is to get this up and running as fast as possible,” said GM spokesman Tom Wickham about the new tooling.

GM is investing $202 million to retool the plant to produce the Volt and Cruze engines.

Source (MLive)

The Chevy Volt’s gasoline engine/generator has a unique role in this car. It doesn’t operate as do gas engines in conventional cars in that it does not turn the driveshaft. The Volt is first and foremost an EV and the engine’s only job is to spin a generator to make electricity whenever the battery reaches its low point.

We have learned that the generator will operate through an ideal RPM range anywhere from around 1400 to 4000 RPMs. The RPM and the engine load are varied by the car’s power electronics based on the need for power, which is assessed and adjusted continuously once the pure EV range is depleted.

Combustion engines run at one of two four-stroke cyles. The most commonly used is the Otto cyle. The Atkinson cycle is more efficient as it allows all four strokes (intake, compression, power and exhaust) to occur in a single turn of the crankshaft. This allows the power stroke to be longer than the compression stroke thereby generating more work for the same  amount of energy.

Toyota, for example, uses an Atkinson cycle engine in its Prius to maximize efficiency and thus fuel economy.  Atkinson cycle engines tend to be lower power and therefore slower off the start, though that is offset in hybrids by electric motor supplementation.

Many people have therefore asked whether GM will use the Atkinson cycle for the Volt’s generator.

GM-Volt has learned from reliable sources it will not. The generation one Volt engine is an Otto engine.

We have no more information than that or the reasoning why, but feel free to speculate in the comment section.

Keep in mind, GM of course has access to Atkinson engines as they are used in their 2-mode hybrid trucks currently on the market.  The Volt generator will also be used as a common part as it will also be the powerplant for the high volume Chevy Cruze.