GM-VOLT : Chevy Volt Electric Car Site

The Chevrolet Volt entered mass production on November 11th, the first 350 cars began shipping to customers on December 13th, and on December 15th the first owners began to take possession.

Sixteen consumers, including me, have been driving saleable Volts as part of an advisory panel for over a month.  These car are performing beautifully though some minor quirks have sometimes appeared.  Part of our job as advisers has been to help point these out.

It turns out some of things I have noticed and reported on here have been acknowledged and engineers have continued to tweak and improve.

For example, I noted early on the brakes seemed to be less intense when moving at low speeds such as when edging into  parking spot.  Last week engineers came out to my home and upgraded some of the car’s software responsible for controlling the brakes.

Vehicle line executive Doug Parks explained that GM has “tweaked the brake calibrations to smooth out the pedal feel throughout its travel.”

I had also noticed the charge port door didn’t seem to close as solidly as I would have liked.  Parks said the “charge door mechanism (has now been) improved on production cars for better latching.”  In fact he noted GM engineers have made significant changes from the test car I am driving.  ”We completed lots of little tweaks here and there and the production cars are even better,” he said.

Vehicle line director Tony Posawatz also advised me that the full production car people are now receiving will be noticeably improved and refined from the captured test fleet version I am driving now.  ”We still feel there is a lot of work to do,”  said Posawatz.  ”There’s always fine tuning of the process whether a physical change or a process change at the plant, that’s just the way things work.”

GM plans to be “very very responsive” to customer feedback says Posawatz, and in fact GM engineers will be “on-call” through the holidays to field any concerns from the first drivers.  ”If we do get feedback from the field we will look at it to see if we can address it,” he said. Change that could be implemented may include “software upgrades, physical changes, etc.”

Posawatz expressed gratitude for the 4-year marathon effort we’ve made here on GM-Volt to promote and contribute to the car, and admitted GM has monitored the site closely and incorporated many of the ideas expressed here into the car.

Thanks to all that have contributed, our car is finally in customers hands.

GM and IBM announced this week that they have partnered to develop the software which GM used to develop and perfect the Chevy Volt. This includes the sophisticated battery simulation software that allowed the car to be developed in only 29 months from the point of greenlight. GM had to project and simulate how the battery would function and operate over a ten year/150,000 mile lifetime in that compressed period, a feat IBMs software helped to achieve. Both IBM supercomputers and software development tools were utilized in the process.

IBM software and supercomputers were also used to design and develop the multitude of electronic controls systems within the the Volt and to determine the optimal way for them to interact, creating an ideal “system of systems” configuration.

“Software and controls are a key differentiator, and have significant value in driving vehicle development and providing unique solutions to our customers, especially in vehicles as advanced as the Chevrolet Volt,” said Micky Bly, GM Executive Director of Global Electrical Systems, Hybrids, Electric Vehicles and Batteries. “We must have the ability to deliver innovative electronics and software faster than our competitors and that requires us to develop our vehicles with a set of world-class software processes and tools.”

“IBM is focused on providing our clients with higher value capabilities that enables them to transform the way they develop and design not just the products they deliver, but innovate in the markets in which they compete,” said Robert LeBlanc, Senior Vice President, Middleware Software, IBM. “The Volt represents the convergence of the manufacturing and digital environments that are at the core of building smarter products.”

The Volt contains and relies on 10 million lines of computer code that controls its 100 electronic components. In comparison, a Boeing 787 Dreamliner has just 8 million lines of code. The Volt is 40% electronic, up from the 5% electronic rate of the typical car in the 1980s. Not only that, but Bly states “we can safely say that there’s a 40 percent to 60 percent increase in software code relative to another (conventional) car.”

In particular, it was IBM’s so-called Rational software that GM used to design and test the Volt. IBM acquired the company Teleologic in 2007 and as a result expanded its Rational Software line into automotive applications. The software enabled engineers to quickly make changes in the system and predict the results on-the-fly as development progressed.

It was GM’s goal to design this incredibly complex car so that its orchestra of computerized electronic processes operate seamlessly below the surface to simply create a fun and pleasant user experience.

It is certainly hoped daily Volt drivers never need to learn about all these items, because if they do, it is likely to mean something has gone wrong.

“We haven’t done a vehicle this complex in the history of GM,” said Bly . “The software–the control side–is what ties together (the mechanical components)…It’s really the heart and soul of how the car performs.”

IBM software itself is not used inside the production car.

Source (IBM) (CNET) and (ZDNet)

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 journalists 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 years 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.

A significant focal point of the Chevrolet Volt launch debriefing that I attended focused on detailing the inner workings of the car’s electric drive unit. This has been dispersed across the Internet often inaccurately and to much controversy that’s rather unwarranted.

I was one of a handful of journalists that attended a presentation by Larry Nitz, GM’s executive director of EVs and hybrids, in which he fully explained the way the system works.

The system was first designed in mid-2007 at which point GM decided to build what up to then was only a concept Chevy Volt. The patent was applied for around that time, and only two weeks ago the company was advised the patent was awarded.

The key components are the 111 kw electric motor, the 55 kw electric motor/generator, and the 62 kw 1.4 L gasoline engine.

The core element is the large electric motor which always turns the driveshaft. The car is always electrically driven. The motor turns the sun gear of a planetary gearset which itself is then connected to the driveshaft through two sets of gears set at a 7 to 1 combined gear reduction ratio. In this state of driving the generator is used to only recapture kinetic energy during motor braking and coasting which is then fed back into the battery. It is grounded to the crankcase by one of three clutches.

The next drive state occurs when the car is still in EV mode, but reaches around 70 mph. At that point the 111 kw electric motor begins to spins too rapidly and loses efficiency, around 6500 rpm. To improve efficiency the system kicks in the smaller 55 kw electric motor to operate in parallel. GM thought a lot about this element and considered instead adding a second gear, but figured they could simply use the generator because at these speeds, “it’s not doing anything, ” said Nitz. “It’s just along for the ride.”

It does so by releasing a second clutch, disengaging the ring of the planetary gearset from its formerly fixed position against the case, which then causes coupling of the generator into the ring gear of the planetary. The parallel input from the smaller motor then allows the RPMs of the larger motor to be reduced, improving the overall efficiency of the system. By allowing the second motor to participate, engineers gained an additional 1 to 2 miles of electric range.

The third state of the system occurs when the battery state of charge drops to a 20 to 25% state of charge, and extended range or charge-sustaining operation commences. There is still a buffer in the battery used to handle the dynamic responses of the vehicle in this mode.

At low speeds, the gas engine comes on board and spins the generator motor simply to produce electricity sufficient to supplement the battery and supply the electric motor. The engine is locked to the generator through a third clutch, and the ring gear stays grounded to the crankcase. GM calls this a weak one motor series that is battery dominant with the engine in the background picking up the average amount of energy the vehicle needs.

The fourth and controversial state commences when the vehicle reaches speeds of 70 mph while in extended range mode.

As in EV mode the ring gear is decoupled from the case by the clutch and the smaller electric motor is once again allowed to operate in parallel with the large motor, increasing the system’s efficiency. The difference here is that the smaller motor is still being turned by the engine and not electricity. Thus the engine becomes coupled with both electric motors and all three work together to turn the driveshaft. Thus the gas engine participates in turning the wheels mechanically although indirectly. The generator is decoupled from the ring gear again when speeds drop back below 70 mph.

Thus although the engine generator can participate in mechanically driving the wheels it never does so directly or in isolation, at all points in time the large electric motor is the main driver of the wheels.

By adding this element, engineers were able to improve fuel efficiency by 10 to 15%.

There has been considerable blogospheric controversy over this as this appears to contradict GM’s previous statements that the engine never drives the wheels. Nitz said GM had to be coy about this element due to intellectual property reasons, and now that the patent has been awarded can finally be more transparent.  He still says there is no solitary direct mechanical drive because to do so would require a clutch to the sun gear decoupling the 111 kw electric motor, something that doesn’t exist and doesn’t happen.

Does this element play a major role? It depends how often you drive over 70 mph and extended range mode.

Next question. How important is it to you?

See a video of Mr. Nitz’ whole presentation here.

The Chevrolet Volt’s technical details are now being laid bare for all the world to see. Motor Trend magazine was the first to get a full debriefing on how the Volt’s powertrain functions and according to GM engineers I have just spoken with, have done an excellent job explaining this.

As you are reading this article I am spending a full day driving the Volt more than 100 miles throughout Detroit in both EV and extended range mode and attending technical briefings on the inner working of the car. More on this soon.

Frank Markus of Motor Trend took the car for an extended test drive and found it lived up well to GM’s promises. He also explains the inner workings of the Volt’s transmission for the first time. The previously reported patent application found by our own reader Cab Driver was confirmed as accurate.

Here’s how it works.

The drivetrain has a bit in common with the Prius and Ford hybrids. It consist of a single planetary gearset, two electric motors, and one gas engine. Motor Trend thinks the design is superior and more efficient than Toyota’s, and according to GM engineers with whom I spoke, is on the verge of patented.

There is a large central sun gear turned by the 149 horsepower electric motor at all times. Around it is a planetary carrier which turns the wheels. When the car is in charge depleting mode, an outer ring is locked to the case. The engine and generator are disengaged.

When the car reaches 70 mph the main motor spins too fast to be maximally efficient, and a clutch disengages the ring from the case. This allows the second electric motor to participate and both motors act in parallel to reach speeds of 101 mph with adequate power.

In charge sustaining mode, the gas engine goes on and clutches to the generator causing it to produce electricity to continue powering the main motor.

However of particular interest, when going above 70 mph in charge sustaining mode, and the generator gets coupled to the drivetrain, the gas engine participates in the motive force. GM says the engine never drives the wheels all by itself, but will participate in this particular situation in the name of efficiency, which is improved by 10 to 15 percent.

Markus liked driving the car and he noted he was surprised about the direct mechnical connection.

Motor Trend found 0 to 60 in 8.8 seconds in EV mode and 8.7 seconds in extended range mode. This difference was verified to me by engineers. Noting it to be “no sports car” the Volt still blows the Prius away (9.8 seconds 0 to 60).

Though not specifically tesing it, Markus said drivers should expect fuel effieicny when running on gas from high 30s to low 40s.

He also noted the Volt will flash a dash message “low propulsion power” when going up steep grades in extended range mode and will drop to 40 MPH. This will not happen if mountain mode is engaged ahead of time, which will leave extra energy in the battery, causing the engine to go on sooner.

They found it quiet as well as quick and nippy in traffic.

The brakes were noted to be suprtior to the Prius, and do an excellent job mating and feathering initial regenerative motor braking and eventual disc caliper braking.

Motor Trend also was abe to map the behavior of the Volt’s generator and found it generally followed power demand in the way a customer would expect.

Motor Trends bottom line: If the gas/electric and plug-in sport sedans (Fisker, Tesla) and supercars (Jag, Lotus, Porsche, Ferrari) are as well-engineered as this subcompact, enthusiasts need not fear the 60-mpg future.

Source (Motor Trend) and (Motor Trend)

There are several pieces of information about the Chevy Volt that have been accepted as immutable fact since early on in the car’s transparent developmental process.  One of those has to do with the amount of usable energy that will be drawn from the battery to drive the car.


We have always been told the Volt would use 8 kwh to drive 40 miles, and thus about 50% of the battery’s total capacity, operating within the roughly 30 to 80 percent state of charge band. This number also indicated the vehicle’s efficiency is roughly 5 miles per kwh


At the Consumer Advisory Board information conference, Volt vehicle line director Tony Posawatz issued an addendum of sorts.  The Volt will use “a little bit more” than 8 kwh.  He would not be specific about how much more, instead assuring us we “will found out” when we start driving the car.


Britta Gross who is GM’s director of infrastructure indicated how much electricity consumers should expect to draw from the grid in order to fully recharge a depleted battery. “Assume an upper bound of 10kWh needed to fully charge the battery (from empty),” said said. This would include grid energy also used to condition the battery.


The Volt will issue monthly statements describing how much energy the car has consumed which will be sent to email via OnStar and be accessible on myvolt.com.


Over time as the battery degrades the car’s electric range will gradually decline.  The pack should reach about 70 to 75% of capacity after 8 years/100,000 miles.  The car will gradually increase the usable state of charge band, however, to continue enabling the 25 to 50 miles of electric range.


The car can continue to be driven long beyond that 8 year/100,000 mile point, and in secondary applications the battery could be used for an equal number of years.  Eventually consumers will see electric range degrade, though the generator will always be there to allow normal usage.


If you’re feeling a little adventurous you can also discuss this post in our new and improved GM-Volt Forum.