Most electric vehicle drivers charge them at home

A car uses a level 2 electric charger on Polk Street across from City Hall in San Francisco. A car uses a level 2 electric charger on Polk Street across from City Hall in San Francisco. Photo: Liz Hafalia / The Chronicle Photo: Liz Hafalia / The Chronicle Image 1 of / 4 Caption Close Most electric vehicle drivers charge them at home 1 / 4 Back to Gallery

In a bid to boost electric car sales, Bay Area cities have installed hundreds of public charging stations where drivers can top off their batteries.

The stations are considered essential to warding off "range anxiety," the fear of running out of electricity on the road. But a new survey suggests that many plug-in car owners rarely use them.

Just 10 percent of charging happens at public stations, according to the survey from PlugInsights. Seven percent of charging takes place at work. In contrast, 81 percent of electric car charging happens at home.

PlugInsights is a service of Recargo, a Southern California company that makes apps for electric vehicle drivers. PlugInsights tapped the growing pool of Recargo users to conduct its survey on drivers' habits and attitudes, gathering data from 3,247 people.

Car companies and electric vehicle advocates have always expected that most charging would happen at home. It's impossible, after all, to beat the convenience of filling up in one's own garage.

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But Norman Hajjar, PlugInsights' managing director, said there's another factor at work. Most public charging stations are "level 2" chargers, which typically add between 10 and 20 miles of driving range for each hour of charge. For many drivers, Hajjar said, that's just not enough.

"Level 2 charging is not a practical way to bridge two distant points," he said. "The majority of people say they're using level 2 charging when they absolutely have to."

Survey respondents had kinder words for level 3 stations, also known as "quick chargers" or "fast chargers." Those can top off a battery in 30 minutes.

But they cost more to install than level 2 chargers, and as a result, remain somewhat rare. According to PlugInsights, there are just over 300 level 3 public charging stations installed across the country, compared with more than 12,000 level 2 public chargers. (Those figures don't include Tesla Motors' proprietary Supercharger stations, which work only with Tesla's Model S sedan.)

Hajjar said government agencies wanting to promote electric cars should install more level 3 chargers on high-traffic routes between cities.

"I would focus on looking at ways of creating urban corridors covered by level 3 chargers," he said. "Without that, (drivers) are on a leash, and they just don't venture far from home."

The Bay Area has 49 public fast chargers, according to the U.S. Department of Energy. That number pales in comparison to the area's 1,186 public level 2 chargers.

The Bay Area Air Quality Management District spent $316,766 to install 172 public level 2 chargers, viewing electric cars as a way of fighting climate change. Damian Breen, director of the district's incentives program, considers the effort worthwhile, even if drivers prefer the faster, level 3 stations.

"You have to understand, what's out there right now is a safety net," he said. "Some of them are highly, highly used, some of them not so much. I think the investment we've made in them is wise, because people know they're not going to get in trouble. They can feel safe using their vehicles."

John Sarter of San Rafael often plugs his Nissan Leaf into public charging stations during work meetings in San Francisco. Several downtown garages include level 2 chargers, which add about 12 miles of range to his battery pack per hour. For obvious reasons, he prefers stations that are free, although it's sometimes hard to find one that isn't occupied.

"The demand is exceeding supply at this point," said Sarter, 52.

And yet he, too, would like to see more public level 3 chargers.

"If I'm really trying to get somewhere, the level 2s really aren't that useful," said Sarter, who has his own green building firm, Off the Grid Design. "If they really want to focus on adoption, they really should focus on level 3s."