Mary Barra and Elon Musk may be intense business rivals, but they sounded like old friends as they chatted. Twitter this month about a deal that could help remove one of the biggest barriers to electric vehicle ownership: not enough chargers.

Barra, the CEO of General Motors, had just agreed to follow Ford Motor in adopting charging technology developed by Tesla, the automaker led by Musk. The agreements will allow GM and Ford customers to use some of Tesla’s fast chargers. Fear of not finding a charger is one of the main reasons some people hesitate to buy electric cars, surveys show.

Barra raved about Tesla’s “fantastic” team. Musk said it was an “honor” to work with her.

Beneath the surface of those jokes, there were probably some difficult corporate calculations. GM, Ford, and numerous charging companies and equipment providers have agreed to work with Tesla because they desperately need the company’s help. In addition to selling more electric cars in the United States than all other automakers combined, Tesla operates the largest fast-charging network in the country.

But the decision to work with Tesla carries great risks for the rest of the auto industry, which will depend on Musk, a mercurial leader, for essential technology. Tesla’s proprietary charging system, which recently began to be called the North American Charging Standard, is not overseen by an independent organization like other technical standards. The company has said it intends to hand over control to that body, though some competitors are skeptical about how much control Tesla will hand over.

The deal also carries risks for Tesla. Exclusive access to the company’s charging stations, some of which already had long lines during busy hours, has helped the company sell cars to customers who might chafe at having to wait behind Ford and Chevrolet.

Battles over technical standards are common with any new technology. The results can be painful for companies or consumers who bet on the wrong horse. Just ask anyone who has bought or invested in a video recorder, cell phone, or digital music player that later became obsolete.

The stakes with cars are much higher: They cost tens of thousands of dollars, and replacing gasoline-powered vehicles with electric models is key to tackling climate change.

Some industry officials fear that complicated corporate maneuvering over charging technology could discourage people from buying electric cars.

“It creates confusion,” said Oleg Logvinov, North American president of the Cargo Interface Initiative. The organization is a forum for manufacturers, equipment suppliers, and charging companies that use Tesla’s main rival to the standard, known as the Combined Charging System.

Buyers, Logvinov added, “will probably wait until I can figure out which one wins.”

Ford, GM, and most manufacturers other than Tesla have made cars with CCS plugs, which are the standard in Europe. Charging networks operated by companies like Electrify America and EVgo primarily offer CCS plugs.

Tesla’s plug is lighter and easier to handle, but it only fits company cars. Under agreements with Ford and GM, Tesla will offer an adapter early next year that will allow cars from those manufacturers to connect to about 12,000 of their fast chargers in the United States. In 2025, Ford and GM plan to make models designed to take the Tesla plug without an adapter.

The combined influence of Tesla, GM, and Ford effectively forces charging network operators to install Tesla plugs and may make the CCS plug obsolete, at least in North America, for years to come. Rivian, a smaller electric vehicle company, said last week it would also switch to Tesla’s plug, and other manufacturers are considering doing so as well.

“For us, it’s important to make sure that charging is really accessible and easy for customers,” RJ Scaringe, Rivian’s chief executive, said in an interview.

As the Tesla plug becomes more mainstream, people with cars designed to use the CCS plug will become increasingly reliant on adapters which, for safety, are limited in how much voltage they can handle and will charge more slowly.

Tesla’s system is known for being easy to use and reliable, while CCS chargers can be finicky. Frustration with the existing charging network is clearly one of the reasons Ford and GM decided to team up with Tesla.

“I absolutely don’t think this would happen if the other networks were more reliable,” said Ben Rose, president of Battle Road Research, which tracks the electric vehicle industry.

But one of the reasons Tesla’s system works well is that the company designs and builds the entire system: the car, the software, and the charging hardware. Tesla will lose complete control once other automakers join its network.

Operating chargers that can power dozens of vehicles from many different manufacturers is extremely difficult.

“We charge 50 different models,” Cathy Zoi, chief executive of charging company EVgo, told an audience in New York this month. Manufacturers sometimes don’t inform EVgo about changes to the vehicle’s software, she said, leading to connection problems. “And the shipper is blamed,” she said.

Tesla built a charging network because there were few places to charge in 2012 when it began selling the Model S, its first full-size passenger car. Tesla doesn’t disclose financial information about the network, but analysts say the company probably loses money by charging people to buy its cars. Tesla did not respond to a request for comment.

Tesla has 19,700 charging ports in the United States at about 1,800 stations, according to the Department of Energy, while there are 10,500 CCS ports at 5,300 stations. Only 12,000 Tesla chargers will be available for Ford, GM and Rivian vehicles.

The decision by other automakers to partner with Tesla and generate revenue for a competitor is an acknowledgment that Musk’s company has the most experience operating a charging network.

Musk has vowed not to disadvantage GM and Ford customers, and the other auto companies say they believe him. “TO The GM customer will be treated as a Tesla customer, and that’s part of the deal,” Alan Wexler, a General Motors executive who handled the negotiations with Tesla, told reporters in New York this month.

But it’s unclear who will make sure the charging equipment is safe and works as well with Tesla’s rivals as it does with Tesla itself, and arbitrate any disputes between the company and other automakers.

Tesla is in talks with the Charge Interface Initiative to designate it to play the same role in the company’s technology that it already does at CCS.

Competitors are betting that government regulators would step in if Tesla tried to create a charging monopoly. Some are glad someone is taking the initiative to remove a major impediment to EV sales.

“We are really on this accelerated growth curve,” said Brendan Jones, chief executive of Blink Charging, which plans to install Tesla plugs on its network. “This will really propel the industry forward.”