Pearlridge Center on Sunday opened the first in a series of electric vehicle charging stations that will let people charge their vehicles for free while they shop, a feature that will be provided at Kahala Mall on Wednesday.

Within six months Volta Industries plans to have 20 to 40 EV charging stations installed across Oahu — all at no cost to consumers.

Volta relies on advertising at its charging stations to generate revenue while providing EV owners free charges, which can take hours to replenish if a vehicle is fully drained.

Oahu had 495 electric vehicles registered as of January.

At a blessing and ceremony at Pearlridge’s Uptown parking lot on Sunday, state Rep. Mark Takai called Volta’s charging station an important step for Hawaii.

Takai lives near the mall and has logged almost 14,000 miles on his 2011 Nissan Leaf, an all-electric car.

"This is fascinating," said Takai (D, Newtown-Pearl City). But Takai already was anticipating problems from the expected demand in the free service at the station near Pearlridge’s main food court.

"With only one stall (at Pearlridge Uptown), the challenge will be to develop some kind of courtesy protocols" among EV owners, Takai said.

Most of Hawaii’s charging stations have been installed at hotels and government buildings and require some kind of fee.

The company Better Place installed a charging station at the Town Center of Mililani that is free to users this year, courtesy of a federal grant, but which will charge a fee after that.

Two-year-old Volta Industries is the first company in Hawaii to underwrite its costs through sponsors. Advertisers will have their messages seen by mall shoppers, said Volta’s co-founder Scott Mercer.

The company is focusing its network of charging stations on Oahu, which has the biggest market in Hawaii for both advertisers and their potential customers, Mercer said.

The use of Volta’s stations will be on a "first-come, first-served" basis and will be available during mall hours at Pearlridge and Kahala, Mercer said.

"There won’t always be someone in line for the charging station," he predicted.

Pearlridge security will monitor the demand, said Fred Paine, Pearlridge Center general manager.

"We don’t really have any rules or regulations," Paine said. "We would love to have a problem where there were too many people that needed the use of it. So we’ll just monitor it, and I’m sure we’ll work something out."

A second free station will be available later this week at Pearlridge Downtown near the entrance closest to Cold Stone Creamery. Kahala Mall will unveil two adjacent EV stations in its parking lot across from Whole Foods on Wednesday, Mercer said.

While fully charging a depleted EV can take up to 15 hours, Mercer said many charges will be far quicker.

For example, he said, a friend drove his EV from Kailua to Pearlridge Center via the H-3 last week to have lunch with Mercer.

Mercer’s friend topped off his batteries in 20 minutes at the Pearlridge station, he said.

Asked how long the network of Volta charging stations will remain free, Mercer said, "It’s free forever."

There are no projections of how the availability of a free charging station might increase the number of shoppers, Paine said.

"We just wanted to be the first to get this done," he said. "We wanted to be the first in the area."