The Tesla Motors Supercharger station in Milford, Conn.Jim Motavalli The Tesla Motors Supercharger station in Milford, Conn.

Tesla Motors officially opened on Friday the first 480-volt Supercharger stations on the East Coast, effectively making possible a Boston-to-Washington trip in the company’s Model S sedan, which the Environmental Protection Agency has rated at 265 miles of range with the larger 85-kilowatt-hour battery pack.

The stations, which can deliver up to 150 miles of range in 30 minutes, are at highway rest areas in Milford, Conn., and Wilmington, Del. On a visit Friday morning, the Milford stations (on both sides of the highway) sat somewhat forlorn under lashings of heavy rain.

On the southbound side, a nonelectric Saab 9-5 was occupying one of two spaces marked with signs reserving them for people charging the Model S, the only car able to use the stations. “We can’t forbid nonelectrics from using the parking spaces,” Shanna Hendriks, a Tesla spokeswoman, said. “We can only hope that people respect the signs.”

The actual stations are more modest than the giant obelisk that Tesla showed the press in September when it opened its first travel corridor, in California. The white chargers are about six feet high and conveniently close to the rest area’s amenities. Tesla developed its own fast-charging protocol, which uses a smaller connector and thinner cable than its competitors.

In an interview earlier in the month, Commissioner Dan Esty of the Connecticut Department of Energy and Environmental Protection said he was proud of the state’s role in bringing Tesla fast charging to the state.

Although the stations were officially opened on Friday, Christina Ra, another Tesla spokeswoman, confirmed that one of the two Milford locations had been ready to dispense electricity before that. A Greenwich real estate agent, Ken Edwards, said in text messages that he plugged his Model S into the southbound side on on Saturday and in 35 minutes added enough power to extend his 70 miles of remaining range to 200.

Other electric cars, like the Nissan Leaf, can be equipped for fast charging. But the Tesla Supercharger network is exclusive to the Model S, which Ms. Ra said was engineered to accept its specific form of rapid electricity transfer. The Tesla Roadster is similarly out of luck, but Ms. Ra said, “In the future, all Tesla models will be able to supercharge.”

All of the Supercharger stations will eventually be supplied by solar power, Ms. Ra said, though it could take a few years before that goal is achieved for the entire network. More stations in the Boston-Washington corridor are also likely, she said.

By JIM MOTAVALLI