Another challenge is the fact that utilities will often charge a hefty “demand charge” per month because of the high load these chargers can put on the grid, says Arindam Maitra, a senior project manager at the Electric Power Research Institute. Fast charger owners will have to pay that fee even if no one uses the station. At least one DC fast-charging system charges $7 per charge, which is more expensive than buying gasoline for the equivalent range in a conventional car.
There are also reasons to doubt that electric vehicle owners will use fast chargers regularly. Most drivers in the U.S. travel less than 100 miles a day, and those who need to travel farther might find electric vehicles inconvenient, even with fast charging. Most of the electric vehicles on the market now and coming out in the next few months travel less than 100 miles on a charge. And cars with a larger range, like Tesla’s Model S—which costs $88,000 for the 300-mile version—are out of the price range of most drivers (see “Can Tesla Survive?”).
If battery costs come down significantly and 300-mile EVs become the norm, fast chargers located between cities such as Los Angeles and San Francisco and Boston and New York could be attractive. Pasquale Romano, CEO of Chargepoint, which has installed a network of about 10,000 conventional charging stations and is starting to add some fast chargers, says: “DC fast charging is very important in long-haul charging and occasional emergency charging. You’d drive a few hours, and stop and have lunch while you charge. They’re needed to make the ecosystem work.”
But Romano doesn’t see such fast chargers becoming common. “It’s not going to be a world where there’s DC everywhere and you’ve replaced gas stations,” he says, adding that most charging will be done at home or at 240-volt charging stations around town.
GM’s head of electric vehicle infrastructure development, Britta Gross, thinks 30 minutes is still too long to wait on a road trip. “Americans are very time-conscious,” she says. GM’s Volt doesn’t require fast-charging for long trips—it just uses the on-board gasoline generator to boost the range by about 300 miles (see “Teardown Reveals the Remarkable Complexity of Chevrolet’s Volt”). GM’s upcoming Spark EV, however, won’t have a gasoline generator to extend its range.
In terms of the adoption of these vehicles, Gross says, the first priority is having inexpensive 240-volt charging stations in people’s homes, followed by similar stations at workplaces for people who don’t have garages at home, both of which would allow electric vehicles to play to their strength—short commutes. She thinks DC fast chargers might have a niche market for those who live in cities and can’t charge at home or at work. They could use the cars to commute, charging up over lunch every few days.
Garrett Beauregard, senior vice president of engineering at Ecotality, is worried about another problem: building too many charging stations, conventional or otherwise, too quickly. “Overpopulation is bad. Some people oppose incentives that have allowed chargers to be installed,” he says. “We don’t want people pointing and saying, these things cost how much, and they haven’t been used in six months?”
Hear more from Tesla at EmTech MIT.