Tuesday June 14th 2011


The Verdict’s in on the Chevy Volt – 4 stars out of 5 for GM’s plug-in hybrid electric car

GM has made a huge leap into the 21st Century by pursuing the Volt. If ever this company needed a new car on which to hang its future, the time is now, and the Volt is it. This car and its future offspring should win back the attention of the motoring public — and we say that genuinely!

40 Vancouver electric vehicle enthusiasts test drove pre-production Chevy Volts.  Guest blogger John Stonier has this (semi-)exclusive look at GM’s new plug-in hybrid EV, in a post first published at evworld.com, whose goal is “to provide a human face to the topic of sustainable transportation.”

General Motors issued a very special invitation to the Vancouver Electric Vehicle Association last week to drive the two Chevrolet Volts visiting the city for the 2010 Winter Olympics. GM generously offered 40 of the Association’s 210 members a unique opportunity to learn more about the car while it is still in pre-production. The event also allowed GM to get feedback from enthusiasts with years of electric car driving experience.

GM has produced 80 third generation pre-production prototypes, two of which came to the Olympic city. This version of the Volt should be close to the final production car due to roll out of a Detroit facility later this spring. Of the 80 cars, most are used for testing and development purposes, but these two vehicles were finished for public display and will be prominently featured during the Olympic Games over the next few weeks. According to GM officials the first production cars will be available in Washington DC, Detroit and California later this fall. Canada should see our first Volts in showrooms later in 2011.

While in Vancouver, the Volt has special licensing arrangements for use only in designated Olympic lanes, and private roadways, so VEVA’s driving course was limited. However everyone had a chance to sit behind the wheel, glide the glossy centre console shift into drive and punch the accelerator to their satisfaction.

GM has put a lot of practical and innovative engineering into this metamorphosis from internal combustion to electric, even though the Volt still carries a piston engine under the hood. The serial electric design (all electric drive, with on-board gasoline generator to recharge the battery when needed) was chosen to take away the range anxiety that continues to pre-occupy the auto industry. As EV purists, VEVA members weren’t so thrilled with this extra complexity for the car. As a first offering from a major auto company, it’s a step in the right direction. A full electric vehicle is only more and better batteries away.

While our test drive opportunities were somewhat limited, VEVA members rated each of the following aspects of the car with one (needs improvement) to five(excellent) stars:

Safety 5 Stars *****

GM has done a very thorough job on safety with the Volt. Any powerful energy technology needs to be treated with respect, and here GM has excelled. The car is controlled by an array of computers that continuously check all of the five main systems on the car through the low voltage 12V system starting when you first turn the key. Not until all system and safety checks are completed does the high voltage traction battery become activated. When charging these checks ensure that no energy flows through the charging plug until all systems are properly connected, and when the plug is removed all high voltage energy is removed from the plug and surrounding area. You can’t activate the car’s traction pack unless the plug is removed.

Visibility from the driver’s seat is good. The colourful and crisp information displays show everything you need just below the sightline. Available all electric range (“AER”) distance is prominently displayed, as well as the gasoline range down to the kilometer, so Volt drivers never have to wonder how much juice is left. You might be distracted from the centre console touch screen which provides three menus displays and controls including energy flows, system status and other cabin features. In the event of an accident, inertial switches immediately open the high voltage contactors, de-energizing the motor drive and traction pack systems, while maintaining low voltage power to braking, steering and all other safety systems remains at the driver’s disposal. Under the hood the complexity is hidden by large plastic covers limiting access to the major components. Easy accessed 12V battery boosting points are prominent at the top of the compartment for the very rare occasion that you might need them (but very handy for giving boosts to drivers of conventional cars). Eight air bags and self-tensioning seat belts round out the main safety features.

Styling and Design 4 Stars ****

When the first concept vehicle rolled down the runway at the Detroit Auto Show in January 2007, the design was sleek and macho. Concepts are concepts, and the production versions seldom seem to live up to their dream car namesakes. The pre-production version of the Volts we drove retains that sleek and distinctive feel of the concept, while also being a practical vehicle for a broad cross section of the driving public. The five-door hatchback design is nicely packaged, making this a versatile sedan with lots of storage.

Inside, the cabin the central console forms an airy channel down the centre of the car. Under it lies the central energy store, the T – shaped traction battery pack that begins near the gear shift and runs aft to the rear of the cabin where it Ts out under the rear floor boards.

All of the drive components are housed under the hood. Between the front wheels lies a consolidation of the electric drive motor, gasoline generator, power control systems, and traction battery charger. When you look at this, there is a lot of complicated equipment here that may be more than many consumers need or want. A larger battery and you could lose more than half of the complicated mechanical components here. See our parting comments.

Efficiency Outlook 4 Stars **** (pending final production car road test)

We won’t know exactly how efficient the Volt will be until we can fully road test a production model. As it is now, the Chevy Volt is the second most aerodynamic car that GM has ever produced. With a coefficient of drag of approximately 0.28 it is second only to that other legendary vehicle produced by GM, the EV-1 (which had an incredibly efficient coefficient of drag of 0.21!).

Thermal management is key to efficiency in electric systems, and here Volt engineers have excelled by crafting integrated liquid cooling and heating throughout the five main systems: Drive motor, drive motor power control, gas engine/generator, traction batteries, and charging. Sophisticated monitoring and control systems ensure that no system overheats, and that electric drive systems are cooled for maximum efficiency. In extreme cold conditions the system ensures that the traction pack does not get too cold – it actually receives heat to ensure top performance.

Rounding out efficiency, GM told us they have been working on new low resistance tires, but we don’t have any specifics to pass on at this point.

Electric Drive Components 4 Stars ****

The drive motor provides 111KW of peak power, more than enough for a sedan of this size and class. The Volt should easily outperform any internal combustion engined car in its class, and at the stated zero – 60mph in 9 seconds, it would be respectable. Our micro-course acceleration trials certainly reaffirmed that potential. Even after the AER has been used, and the Volt is running on its 53KW gasoline generator, a full 111KW of power is still available for acceleration due to the battery management system that always keeps enough energy in reserve for such bursts when required. (We have no pictures to show you. GM insisted no photos be taken under the hood.)

Volt drivers immediately feel the power of electric traction, and the elegance of power without excessive clatter or emissions. Acceleration is responsive and re-assuring, as is the electric ‘regen’ braking (reclaiming some of the energy used to accelerate back into the traction pack). This should extend the service duty of the four wheel disc brakes two to three times that of conventional cars. Energy flows are displayed in real-time on the centre console depicted as “balls” of energy that pulse either to the wheels while accelerating or from the wheels when regen braking. Is this a good thing? VEVA feels that educating drivers and passengers of real time energy flows are the perfect feedback loop for training more efficient drivers over the long term.

Traction Pack (16KWh High Voltage Battery) 4 Stars ****

For the traction pack (the ‘gas tank’ of the future) GM selected LG Chem’s lithium manganese chemistry for this supplier’s quality control and long term experience. It was not a linear decision from all accounts. More than 200 cells provide a total voltage of 380V and 16KWh of energy, enough (GM says) to power the vehicle 64km AER, and approximately 500km under generator assisted power. We think the design consideration to use fewer cells (compared to the Tesla roadster at 6,800 cells) is a good and sensible choice for both reliability and safety. Fewer connections mean fewer potential points of failure.

The gas generator charging system is designed to always leave enough juice in the traction pack to operate the car normally, even if you’ve reached the gas tank range threshold. This approach protects the traction pack from discharging beyond the limits that threaten performance longevity.

The Volt’s battery management system design has paid strict attention to the fundamentally important factor of active thermal management. This means that all electrical components are kept within their appropriate operating temperatures; cooled when more efficiency results, and in the event of freezing temperatures, warmed to provide full performance in all conditions. This feature alone will go a long way to ensuring long term performance and safety of the traction pack.

GM officials stated that, on average, 75% of drivers don’t drive more than 64km per day, so it’s possible that some people may never touch the fuel in the tank for the generator. Will the fuel go stale? According to GM, there are routines built into the generator system that will turn the generator on during regular operation periodically to ensure that this won’t happen, and to ensure that this system gets a regular work-out to ensure reliability.

We think the size of the main traction pack could be larger. GM has chosen a very reliable lithium ion chemistry from a very reliable supplier. GM’s choice results in lower energy density than other formulations available, and therefore less energy storage on board. Also, lithium manganese batteries deliver lower peak power than other chemistries, limiting the potential performance possible. Other electric cars currently in production have 50-230% more energy storage on board (e.g. Tesla Roadster, 400km or 250 mile range, 53KWh), and will use chemistries that will provide more punch in power. This is not a bad thing for the extended range hybrid Volt, but GM has actively chosen not to pursue more AER than 64km.

Despite these reservations we believe Volt engineers have built a solid traction battery system and platform which should facilitate evolution to a full electric version of the product line. We hope it won’t be long before GM will offer a full electric vehicle, without the gasoline auxiliary power system complexity; the additional manufacturing cost; and longer term maintenance costs that come with this component.

Think EV-2. All the elegance of the original EV-1, with the substantial improvements to energy storage and human interface technology advanced by the mobile electronics and internet sectors in the last ten years. In the next ten years, the focus will be on even more improvements to large format battery technology, and this is where we should be able to say good bye to the internal combustion engine for most applications.

Re-Charging Systems and Times: 4 Stars ****

Chevrolet is using the new SAE J1772 charging plug standard. Two cords come with the car, one for your home garage to be hard-wired into your house by a qualified electrician. A second cord is stored in the trunk for charging away from home, and can plug into any 120V or 240V conventional outlets.

This is much less expensive than some of the other proposed charging systems where electric car companies are offering multi-thousand dollar home charging systems (plus installation charges). The home cord will be wired to a 240V– 30A circuit in your home, essentially the same as your normal dryer plug. The SAE J1772 system does allow for higher amperages, so an oven plug (240V – 50A) service would be preferable – both are standard wiring in North American homes. In any case, the Volt is only going to draw just above 20A during any charge period, or about 3 hours on a 240V circuit for a fully discharged battery. (10 hours with regular 120V outlets).

Mobile Interface: Will your car have its own face book page too? 5 Stars *****

In the human interface area, GM has really done something fantastic. Leveraging their On-Star two-way communications network, Volt engineers have interfaced scheduled charging and vehicle monitoring into the latest downloadable app for your mobile phone (you can also do this from the console inside the car directly). Volt owners will be able to schedule what time they want their cars to charge which will take advantage of lower overnight rates for electricity, where available, or, simply ensure that your car is fully juiced for regular use. It will also tell you what the state of charge is at any time, and monitor key events such as when your charging is interrupted for any reason. This is just the beginning of the technological features electric car will make reality, and we look forward to more innovation in the future.

Overall: 4 Stars ****

GM has made a huge leap into the 21st Century by pursuing the Volt. If ever this company needed a new car on which to hang its future, the time is now, and the Volt is it. This car and its future offspring should win back the attention of the motoring public — and we say that genuinely!

The next step must be a full electric model without the secondary gas powered system under the hood, never the less, we are pleased with the results to date, and we look forward to seeing the Volt in showrooms soon.

– John Stonier

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This article was originally posted on Climate Progress