Published: Dec 19, 2014 1:10 p.m. ET

By CLAUDIA ASSIS ENERGY REPORTER

SAN FRANCISCO (MarketWatch) — Tesla Motors Inc. Chief Executive Elon Musk tweeted Friday that a battery-pack swap station for the company’s electric cars is operating between San Francisco and Los Angeles in “limited beta mode.”

In a video on Tesla’s website, Musk is seen talking in general about battery swaps. He says the swap option will be another step in “convincing the skeptics” that an electric car is more convenient than a gasoline-powered car.

“That’s what convinces people finally that electric cars are the future,” Musk said in the video, which compares an Audi filling up at a gas station and a Model S having its battery swapped.

In the video, it takes the Audi about 4 minutes to leave the gas station, enough time for two Teslas to get their batteries swapped.

Drivers can either use a Tesla TSLA, -0.51% supercharger station to recharge the battery in their car, which is free, or choose to swap the battery, which would take a minute and a half but not be free, Musk says in the video.

According to Tesla’s website, supercharger stations can provide half a charge to car batteries in as little as 20 minutes. There are 142 Tesla supercharger stations in North America, according to Tesla, including at least seven between San Francisco and Los Angeles.

Tesla is based in Palo Alto, Calif., some 40 miles south of San Francisco. Tesla owners can also use other charging stations, but it would take longer to power up their cars.

Tesla shares fell 1% on Friday, but looked poised to end the week up 4%. So far this year, Tesla shares have gained 44%, which compares to gains of 12% for the S&P 500 index SPX, +0.33% and gains of 2.4% for the Russell 2000 RUT, +0.14% a small-cap benchmark.