Two more sets of car-charging stations are being unveiled in the Triangle, part of a growing effort to test the technology as well as assure owners of electric vehicles that they won’t be too far from a charge.

Morrisville recently postponed plans to hold a ribbon-cutting ceremony on a pair of charging stations in the parking lot of the town Chamber of Commerce but plans to reschedule soon. Meanwhile, the Durham Museum of Life and Science was set to make two car-charging stations available starting Saturday. Both sets of chargers are free and open to the public.

Demand for the stations remains modest at best; all-electric vehicles like the Chevy Volt and the Nissan Leaf remain an unusual sight on Triangle roads.

But it’s important to lay the groundwork for electric cars so that drivers consider them a viable option, said Jeff Barghout, director of transportation initiatives for Advanced Energy, a North Carolina-based nonprofit that works to help utilities develop energy efficiency measures, such as Duke Energy’s plug-in vehicle study.

“It’s a ‘the chicken or the egg’ situation,” Barghout said.

The Morrisville stations are part of a two-year study started by Progress Energy to understand the impact of charging vehicles on the electric grid. The company, now Duke Energy, is using the stations to track how often they are used and when. Duke will track the stations’ use until the program ends in April.

Duke has installed 42 stations across the state, 18 of them in the Triangle. In addition to the chargers at the Durham Museum of Life and Science, the company hopes to install six more before the end of the study.

Duke Energy won’t release data on the stations until the study ends, but Advanced Energy’s Barghout said their use has increased over the period of the study.

Duke Energy’s charging stations are far from the only ones on the street. The city of Raleigh has installed several units as part of its plan to become a national leader in electric-vehicle preparations.

In 2009, Raleigh was one of three cities to partner with the Rocky Mountain Institute on Project Get Ready, which aims to help cities prepare for the growth of electric vehicles.

As part of the initiative, the city has installed 29 charging stations, with 18 of them open to the public and the other 11 reserved for the city’s fleet of electric vehicles.

Raleigh’s stations were used 4,737 times in 2012, said Donnamaria Harris, spokeswoman for the Office of Sustainability, noting that numbers increased each quarter. Harris said the average charge time was between one and two hours, suggesting that drivers are using the city’s stations to “top off” their batteries rather than fully charge their vehicles.

A Virginia-based company, Evatran, will soon install wireless charging stations for use by Raleigh city vehicles. Evatran’s chargers are mounted to the ground, much like a manhole cover, allowing a vehicle to park over the charger and refuel without being physically plugged in.

Raleigh will be a pilot program for the new technology, meaning there will be no cost to the city.

Raleigh’s Praxis Technologies has also gotten in on the charging-station boom. In 2011, the company received a grant enabling it to distribute 19 stations to different groups across the state, including the American Tobacco Campus in Durham and the American Institute of Architects headquarters in Raleigh.

The chargers at AIA’s building are used several times a week, by residents and people coming to the building for presentations, said David Crawford, the group’s executive vice president. AIA might be ahead of the electric car trend, but Crawford felt the units fit the building’s purpose.

“The community knew this was a project for sustainability,” he said. “We wanted to incorporate green technology.”

Albert Kurz, Praxis’ CEO, estimates that all 19 of the company’s charging stations were used about 5,000 times in 2012, a substantial increase over previous years. About 80 percent of those charging sessions took place in the Triangle.

Praxis’ units were not installed to meet an existing demand but to set up a system for a future in which electric cars are the norm.

“We did not go out with the expectation they would be used immediately,” said Kurz.

Kurz said the company’s goal for the units was to help combat “range anxiety”: drivers’ concern that an electric car’s battery will run out of energy before they reach their destination. Praxis’ hope is that its units will help the public become more comfortable with the idea of electric vehicles.