That service could cost Volta $6-8 per charge at 100kW stations, depending on the electricity costs in your area, so how are they making money? Volta's revenue model is based on advertising, and it seems the locations are also sponsoring the charging stations to some extent. "Volta optimizes the convergence of electric vehicles, real estate owners and brands," the company wrote. "Brick and mortar locations benefit by attracting upscale customers and hosting them for longer while sponsoring brands leverage the stations to generate meaningful uplift."

In other words, EV owners are often high earners who might spend lots of money shopping, and advertisers using Volta's big screens will also get to target these folks. That demographic trick may work well at upscale shopping spots, trendy organic supermarkets and other places where well-to-do, environmentally conscious shoppers hang out.

Volta's current business model works in a similar way, but until now, it hasn't provided any fast-charging stations. For the new network, the company will use "data modeling and venue customer behavior" to find the ideal mix between fast and Level 2 chargers. Fast chargers will have power levels from 50 to 100kW, and you'll initiate charging via Volta's mobile app. Volta will determine where to put the new charging stations based on "data-driven models that forecast charging trends," it said.

The first free Volta DC fast-charging station will be arrive in Norwalk, Connecticut later this month. The company will then focus on larger cities like Los Angeles, San Francisco, Washington DC and Chicago.