White Marsh Mall in northern Baltimore County has eight Level 2 charging stations. The Volta stations are free and are supported by ads displayed on a large screen. Signs at each station limit a stay at two hours.
The eight Voltas are distributed around the perimeter of the mall. When I was there on a Saturday evening, all eight were open and available.
On a side note, the IKEA store adjacent to the White Marsh Mall is having a big solar canopy being built in their parking lot. There are also five ChargePoint Level 2 charging stations in the White Marsh Park and Ride lot.
Keep an eye out for Volta free charging stations at other retail shopping areas. They seem to be making a push for expanding in the Washington, DC and Baltimore area.