There have been electric cars almost as long as there have been cars, but for the last eighty years of the electric car’s life, it has been relegated to the farthest fringes of the automotive universe. Electrics have been held back by their batteries, which don’t pack nearly as much energy as a tank of gasoline and therefore hobble these cars with a painfully short driving range.
General Motors, Toyota, and others who toyed with electric cars in the recent past proved that neither lead-acid nor nickel-metal-hydride batteries had the moxie to dependably propel us down the road. The move toward electric propulsion spun its wheels until engineers eager to tap clean, quiet power came up with an interim plan: team electric energy with internal combustion. The concept was called hybrid propulsion, and the first hybrid arrived here for sale in late 1999.
Even though the Honda Insight was priced below $20,000 and was EPA-rated at 70 mpg on the highway, America wasn’t ready for a weird-looking two-seater, no matter how much gas it saved or how generously Honda subsidized the price. The Insight was crushed by the sensible-shoes Toyota Prius hybrid, which arrived eight months later (after a three-year warm-up in Japan).
All hybrids now bow to the Prius’s success. In spite of its confoundedly complex gas and electric powertrain, Toyota has sold more than a million of them in forty-plus countries. Investments in hybrid technology have begun paying off.
But for hard-core electric fans, the Prius is merely the initial crack in a clean break from internal combustion. The goal is to plug into the electrical grid to avoid gas pumps at any cost. Some of them are spending more than $100,000 for a Tesla Roadster.
The plug-in movement, which began with the radical fringe, is now gathering momentum. Practically every hybrid-vehicle manufacturer has an experimental plug-in on the auto-show circuit or gathering test-fleet data. The aftermarket has also joined the party. A123Systems in Watertown, Massachusetts, sells a $9995 Hymotion L5 Plug-In Conversion for 2004 through 2009 Toyota Priuses. This 5-kilowatt-hour (kW-h) lithium-ion (Li-ion) battery piggybacks the factory’s 1.3-kW-h nickel-metal-hydride (NiMH) batteries. While pure-electric driving is still limited to speeds of up to only about 20 mph, the division of labor is shifted in favor of the cleaner, cheaper electric side of the Prius’s propulsion system. Li-ion batteries are not silver bullets, but they provide some 50 percent greater energy storage capacity than the NiMH batteries currently in hybrid use.
Enter the Volt
Squeezing more miles out of each gallon by using electricity makes sense in a world of increasingly expensive petroleum. A smarter way to solve the hybrid equation is by using smidgens of gasoline to make electric cars attractive to tomorrow’s commuters. This is the game changer, the plug-in car that fans have been advocating.
You already know that the Chevrolet Volt has a battery pack that, when plugged in overnight, provides about 40 miles of pure-electric driving. Now that the wraps are off the production version scheduled for sale in two years, GM is finally adding information to the hype clouding this project.
The Volt will be a four-passenger, hatchback sedan. Major chassis components are shared with GM’s new global compact platform, but extensive alterations were required to accommodate the five-foot-long, T-shaped Li-ion battery pack. If the show car was a chopped-top Camaro with vestigial rear doors, the production aesthetic leans more toward the Chevy Cruze that debuted at the Paris show. Here’s why: Few budget- and energy-minded consumers purchase racy-looking cars. The squished roofline left insufficient headroom for four adults. And, according to designer Bob Boniface, 400 hours of wind-tunnel effort trimmed the Volt’s drag coefficient by 30 percent, thereby adding several critical miles to its electric-only range.
A 149-hp (111-kW) AC motor drives the Volt’s front wheels through speed-reduction and differential gears. All of the propulsion torque flows via this path. For that and other reasons, GM calls the Volt an electric car – specifically an Extended-Range Electric Vehicle, or E-Rev – versus a plug-in hybrid.
The word hybrid has traditionally described a vehicle employing two forms of energy conversion. By this definition, the Volt is a series hybrid, because the energy produced by combustion is converted to electricity before it’s used to drive the wheels. Jon Lauckner, GM’s VP of global program management, believes otherwise and offered these reasons why the Volt is not a hybrid:
- Propulsion is handled strictly by the electric motor.
- The gasoline engine runs only when the battery is depleted.
- The car’s performance is determined by the drive motor and battery system.
- The primary fuel is electricity.
We expect the court of common sense to find GM guilty of coining yet another catchy name – plus the inevitable acronym – that only confuses those interested in joining the plug-in movement. But how the Volt is categorized pales in comparison with how far it leaps ahead of Toyota in the green-car game.
The Volt’s battery pack consists of more than 220 Li-ion cells capable of storing 16 kW-h of energy. Each cell is roughly the size and shape of a thin paperback book. Compared with the cylindrical cells powering the Tesla Roadster, this prismatic configuration is advantageous for both packaging and temperature distribution. A cylindrical cell tends to be hot at its center and cool at its periphery, while a flatter cell has an even temperature distribution that’s easier to maintain with a cooling system.
After initial discussions with twenty-three battery companies, GM began working in earnest last year with two cell producers – LG Chem based in Korea and A123Systems, the firm selling Li-ion batteries to Prius owners craving extra wattage. Although production contracts are pending, clues offered about the specific chemistry inside the cells suggest that LG Chem will be GM’s battery supplier.
While Li-ion batteries typically last no more than a few years in laptop and cell phone applications, such short service won’t cut it in the car world. Since the Volt’s batteries are considered part of its emissions control system, they must be guaranteed for eight or ten years, depending on the state where the car is sold. To stretch the useful life of the Volt’s batteries, GM engineers developed means of precisely monitoring their state of charge so that the pack can be maintained between 30 and 80 percent of its total capacity. A second measure is keeping the battery pack’s temperature between 68 and 77 degrees Fahrenheit during driving and while plugged in for recharging. GM vice chairman Bob Lutz adds, “We’re putting a very generous warranty provision into the Volt’s cost structure, because the only real way to simulate ten years [of battery use] is to wait ten years.”
Plugging into a 110/120-volt wall socket for eight hours or a 220/240-volt outlet for three hours charges the Volt for daily pollution-free commuting while consuming about a dollar’s worth of electricity. When a trip exceeds 40 miles, a 1.4-liter four-cylinder engine powering a 53-kW AC generator automatically fires up to relieve the battery pack as the source of electrical energy. This engine, which has an aluminum head topping an iron block, will run at some (unspecified) constant speed between 2000 and 4000 rpm. To minimize noise and vibration, the Volt’s propulsion motor, gasoline engine, and generator are bolted together in one assembly supported by rubber mounts.
Thanks to its onboard generator fueled by a few gallons of gasoline, the Volt doesn’t have the bugaboo that plagues every other electric car (including the Tesla Roadster): what GM aptly calls “range anxiety.” Instead of praying you make it home before the last state-of-charge bar winks off, you drive placidly on for a couple hundred more miles with the gasoline-powered generator supplying the electricity. The generator doesn’t fully recharge the battery pack, because you can do that by plugging in at home for one-sixth the cost.
The Volt already has legions of both advocates and detractors. Tree huggers can’t wait to get their arms around them. Hollywood writer and director Chris Paine is filming a sequel to Who Killed the Electric Car? called Revenge of the Electric Car. The government sees the Volt as the near-term payback for taxpayer money previously invested in advanced propulsion research. The electric utilities are giddy over kilowatt cars, because recharging them in the evening will make better use of their existing generating capacity (read: increased revenue).
On the negative side, Dr. Menahem Anderman, president of Advanced Automotive Batteries, is doubtful that Li-ion batteries are ready for prime time. And while no one we queried felt the Volt will generate a profit for years, John Casesa, a leading auto-industry analyst, believes that Wall Street appreciates GM’s leap forward with new technology and investors will therefore be more willing to own its stock.
Car enthusiasts will surely regard the Volt as the perfect car for their parents. With a curb weight of about 3700 pounds, a 9.0-second 0-to-60-mph acceleration rate, and a top speed limited to 100 mph, the Volt’s driving thrills will be modest. Since all 273 lb-ft of its torque is available at 0 rpm, the surge from a stoplight will feel like the initial rush of a skyscraper’s elevator. But Volt owners are more likely to take pride in the three-digit gas-mileage rating expected from the EPA.
Economics will strongly influence the Volt’s prospects for success. Lutz hopes that the government will offer early Volt adopters a $7500 reason to join the plug-in movement. A second incentive will be the $1700 or so annual savings available to those who drive a Volt in pure-electric mode 15,000 miles per year in place of a gasoline-powered car. But the grandest What’s Next is the Volt’s price. We’re guessing it will cost $34,995 after the government’s rebate, but no one can accurately predict what life will be like in 2010.
Bob Lutz, GM’s vice chairman of global product development, switched his electric car polarity about a decade ago. The epiphany came while he was CEO of Exide Technologies, a leading lead-acid battery maker. “I used to be a huge opponent of electric vehicles,” Lutz recently recalled, “and I delivered thoughtful speeches about what nonsense they were. But at Exide, I learned about battery technology. As is the case with internal combustion engines, constant development has yielded a two-percent rise in lead-acid efficiency every year.
“I became fascinated by the idea of a fully electric car, but there was no budget at Exide to build the advanced lead-acid concept car I had in mind. I believed that when lithium-ion came onstream, it would be possible to store enough energy to get it done.”
In January 2006, Lutz summoned Jon Lauckner, GM’s VP of program management, to discuss building a pure electric car for the 2007 Detroit auto show. Instead of saluting the boss’s proposal, Lauckner objected. “I felt that a battery/electric compact with 300 miles of range would have no room for passengers,” he remembers. “So I proposed an alternative, which became the Volt: a battery just large enough to cover daily commuting needs backed up by a small engine-driven generator for longer trips.
“Since that meeting, we studied various alternatives but kept coming back to the Volt’s configuration. In contrast to technologies aimed at more efficient uses of fuel, this approach begins to sever the link between petroleum and the automobile.”