The electric car maker Tesla plans to swiftly multiply its supercharger stations across the US so drivers can travel coast to coast without worrying about losing power.

CEO Elon Musk said the company would triple the number of stations by June and expand again to have them in most cities in the US and Canada by the end of the year.

"It is very important to address this issue of long-distance travel," he said on Wednesday. "When people buy a car, they're also buying a sense of freedom, the ability to go anywhere they want and not feel fettered."

Tesla has supercharger stations, which allow drivers to recharge in about an hour, on the east coast as well as California and Nevada. In between drivers must charge overnight using ordinary electric current, a serious limitation.

Within two years Tesla plans to have almost the entire country, not just big cities, within range of a supercharger.

Musk's announcement followed a spate of good news for Tesla – it is now profitable and earning rave reviews – as well as more problematic headlines about Musk's admiration for Margaret Thatcher and his withdrawal from a Mark Zuckerberg-backed political advocacy group.

Musk, speaking at a question-and-answer session at the All Things Digital conference in Rancho Palos Verdes, California, said updates to Tesla cars will give drivers a map of charging stations.

The ability to use superchargers is standard on high-range Tesla models and optional on cheaper models.

In addition to spreading across the continental US the network will add more stations to heavily trafficked routes such as the corridor between New York, Boston and Washington DC, which will have a station every 80 to 100 miles.

Musk said Tesla hoped to improve the technology so Model S cars could get three hours of driving time from just 20 minutes of charging. He plans to drive his five children in a Model S from Los Angeles to New York this summer.

The billionaire, who also founded Space X and Solar City, clashed with the New York Times earlier this year when a reviewer, John Broder, said he ran out of power and was stranded while trying to drive from Washington to Boston using the supercharger network.

Musk accused Broder of taking a detour to deliberately run out of power, triggering an acrimonious exchange. The paper's public editor concluded the reviewer took what appeared to be casual and imprecise notes, leaving him open to valid criticism, but acted in good faith.

Musk revisited the row in his conference speech and alleged Broder committed a "low-grade ethics violation".

The Model S has since won glowing reviews elsewhere. Tesla has become profitable and its share price topped $100 this week for the first time. Musk said economies of scale and technological refinements should let the company produce a car priced under $40,000 within a few years.

He said he decided to make electric cars because sustainable transport was needed yet manufacturers shunned the idea. "The industry was operating under two false premises. One, that you could not create a compelling electric car. And two, that no one would buy it."

Musk made headlines earlier this month by dropping out of fwd.us, a Zuckerberg-sponsored political action committee pressing for immigration reform. The group stirred uproar among liberals by supporting pro-immigration reform politicians who also backed oil drilling in Alaska and the Keystone XL pipeline.

"Initially, I agreed to be a part of FWD.us because I agree with immigration reform. But I think the methods that were employed - it was a little too Kissinger-esque, Realpolitik," said Musk. "We shouldn't give in to the politics. If we give in to that, we'll get the political system we deserve."

An earlier, fleeting foray into politics in April stung the tycoon when he tweeted about Britain's late prime minister. "Always admired Margaret Thatcher. She was tough, but sensible & fair, much like my English nana."

Indignation and trolling prompted him to step back. "No more political comments for me now that I've shot off both my feet."