CHICAGO — It’s about noon on a Tuesday and Nina Simms is 3 1/2 hours into the workday, her eyes shifting from her laptop only long enough to take a sip from her water glass, which sits next to an empty coffee cup. When the 28-year-old Evanston, Ill., graduate student is done, she won’t punch out at a time clock; instead, she’ll leave her neighborhood coffee shop.

Laptop users like Simms are increasingly soaking up wireless Internet connections and electrical outlets at their local coffee shops, along with their lattes. Their presence creates a delicate challenge for some owners who want to keep a welcoming atmosphere but also maintain the type of customer turnover necessary to run a profitable business.

Some coffee shop owners try to strike a balance by providing free Wi-Fi connections in two-hour windows, requiring patrons to make a purchase to receive the Wi-Fi password. In some high traffic Starbucks locations in New York City, managers have resorted to blocking access to electrical outlets, the idea being that laptop users will pick up and leave when their batteries run dry.

Panera Bread locations around Chicago and the suburbs limit customers to 30 minutes of W-Fi access daily during the lunch rush, employees at several locations said, and have done so for the last couple of years.

Sony is even developing an electrical outlet that can read a user’s identity and set limits on electricity use, essentially allowing businesses to charge people for charging their devices.

At Cafe Jumping Bean in Chicago’s Pilsen neighborhood, owner Eleazar Delgado blocks Wi-Fi access during peak weekday afternoon hours and all day on weekends.

He started limiting access in late 2007 after receiving complaints from crucial lunch-crowd customers who couldn’t find a seat among laptop users. When some people called him “nuts,” he worried the decision would kill his 18-year-old business. Instead, the move proved fruitful — revenue increased easily by 30 percent, he said.

“I was amazed,” Delgado said. “The weekend policy worked like a charm. … People were hanging out. Now we have space for people to eat.”

In fact, he’s mulling eliminating Wi-Fi access.

But John Kim, one of two brothers behind The Brothers K Coffeehouse in Evanston, Ill., a popular cafe for Simms and other laptop squatters, doesn’t see the point of charging for or blocking Internet access.

“If it gets to that point of business where you’re watching to that minuscule a detail, you’re missing the point of a coffeehouse,” Kim said. “I love it, as long as I have space for it, which is generally the case.”

In fact, he placed plug multipliers at each electrical outlet, and installed a counter along two windows where laptop users can post up to enjoy the view. He thinks the time may come when he and his brother have to start encouraging laptop users to move along. For now, he plans to upgrade the Wi-Fi system with a faster Internet connection.

“I view this as a place where anyone and everyone can come,” he said. “Until we’re full a lot, it won’t be an issue.”

For laptop workers, coffee shops offer a form of social interaction more commonly found in a traditional office environment, and rarely afforded in one’s living room or home office.

According to a December 2010 survey of 1,000 people by the nonprofit global human resources association WorldatWork, 34 percent of U.S. respondents said they worked from a cafe or restaurant in the past month, up from 23 percent in 2008.

“We’re social animals. We like to have other people around,” said Kate Lister, president of Telework Research Network, a research firm that focuses on work conducted outside of the office. Today’s coffee shops hark back to the marketplaces of medieval times, she said, where groups of entrepreneurs can gather and make business connections.

“The coffee shop is the next chamber of commerce,” she said.

Though one would think of the bustle of a neighborhood coffee shop as a distraction, the occasional grinding noise of coffee beans or the political debate at a nearby table actually allows some laptop users to better concentrate on work.

“I like having activity that is not personally relevant to me,” Simms said. “It’s not too quiet, but not too distracting.”

Simms spends four to five hours every weekday and some weekends working from Brothers K, and typically buys just a latte and a bagel.

“It usually takes three hours to finish a drink and any space constraints usually don’t exist then,” she said.