|Electric cars can take a while to charge. In part, thatís because the alternating current electricity that comes from the grid has to be converted to direct current before a carís batteries can store it, and the capacity of the electronics that make the A.C.-to-D.C. conversion is a bottleneck.
General Motors may have a way around that. The electric version of the Chevrolet Spark, G.M.ís second offering in the electric vehicle market, comes with a standard SAE port for A.C. charging as well as two extra receptacles that will accept a D.C. charge. The charging system also includes a communications link so that the car can tell the charger its optimum voltage and amperage numbers.
There is a catch: at present, it is difficult to find a D.C. charger.
Several companies are developing D.C. electric vehicle chargers, which will certainly lend an extra bit of complexity to the process of coming up with charging network standards. Eaton and Fuji Electric are a couple of the companies with D.C. quick chargers on the market.
Connectivity may also be an issue. The Spark EV is the first electric vehicle to be equipped with the American-spec A.C. port plus D.C. port in a combo plug. The Nissan Leaf and the Mitsubishi i-MiEV also have provisions for D.C. charging, but their charging ports are for Japanese Chademo-standard chargers.
The Sparkís extra circuitry could make a considerable difference, said Larry Nitz, G.M.ís director of global electrification. According to G.M., on 110-volt house current, a charger delivers one kilowatt of power; on a 220-volt circuit, the kind that runs an electric oven or clothes dryer and which most buyers are expected to use for home E.V. charging, a charger delivers three to six kilowatts.
But a D.C. charge can deliver 50 kilowatts, he said, and a fully depleted Spark could be restored to an 80 percent charge in 20 minutes. The D.C. quick-charge capability is not intended for home use, but for public places, Mr. Nitz said. New York Cityís expanding grid of fast charging stations would seem to be likely candidates for such technology.
The D.C. quick charge system would be of less importance for the Chevy Volt Ė which can run on gasoline when its battery pack is low Ė than to the electric-only Spark, which has no gas engine as a back-up.
G.M. has not said exactly how far an 80 percent charge will take the Spark EV; in fact it has not said what the carís range is. But the automaker showed off the Spark on Tuesday at a factory northeast of Baltimore that it said was the first in the country to make drive motors for electric cars. (Hitachi produces the Voltís drive motor.)
A Spark EV I drove around a test track achieved, according to a dashboard display, 4.2 miles per kilowatt-hour Ė which one grass-roots calculator estimates is the E.V. version of 121 miles per gallon Ė on a 1.6-mile course. The test drive included some speeds typical of urban traffic and one neck-bending jackrabbit acceleration. The Spark EV weighs about 3,000 pounds and goes from zero to 60 miles an hour in under 8 seconds.
Unlike the Nissan Leaf, which was designed from the ground up as an electric car, the Spark EV is adapted from a gasoline model. Engineers say they made it more aerodynamic with adaptations like block-off panels where the grille used to be. The panels are stamped in a grille-like pattern without actual openings, because the car does not need the air flow through the compartment. Under the grille, the Spark EV has an air intake with louvers that automatically close at high speed to reduce drag.
The Chevrolet Spark EV will be introduced this summer in California and Oregon. Company officials predict modest sales. Whether a $12,995 gasoline-powered minicar assembled in Korea can be turned into a strong-selling battery-powered electric at nearly twice the price remains to be seen; G.M. said the Spark EV would sell for less than $25,000 after tax incentives.
What is certain is that the electric vehicle industry is in its infancy, meaning many of its facets are still in flux. Which mode of charging will emerge as the dominant one Ė public or private, 110 volts or 220 volts, A.C. or D.C., American- or Japanese-spec Ė is far from settled.