Shares of Ford Motor Co rose more than 7% on Friday after the No. 2 US automaker announced plans to allow its electric-vehicle owners access to rival Tesla Inc’s charging stations in North America.

Ford CEO Jim Farley told CNBC that Tesla’s Supercharger could become the standard for electric vehicle charging in the US, but added: “With the adapter and the software, we don’t really have to choose what the standard is now, but I do. Think it will work in the free market.”

Ford shares rose 7.6% to $12.25 in afternoon trading, while Tesla shares rose 7.5% to $197.95.

US Transportation Secretary Pete Buttigieg praised the Ford-Tesla deal but told CNBC that the Biden administration will not mandate electric vehicle charging standards. “Tesla has built a phenomenal network. I think it’s great news to have them be a part of this effort.”

Access to charging stations has so far been seen as one of the main obstacles to wider adoption of electric vehicles, analysts said.

Farley added that GM and other automakers will “make a big choice” between Tesla’s EV charger and the Combined Charging System (CCS).

CCS is a competing charging plug standard for DC fast charging.

GM says an open charging network and standards are the best way to drive EV adoption across the industry, and that it has worked with other automakers to develop an open connector standard in CCS, a “truly universal solution”, available now for fast charging.

Since 2012, Tesla has developed and deployed its own high-speed on-board charger, called the Supercharger, which can add 322 miles (518 kilometres) of range in just 15 minutes.

Farley said Ford has about 10,000 fast chargers, and the deal with Tesla will double that number.