I'm not happy about the Supercharger location in Providence, RI. It seems to only work for people coming from NYC to the Cape, and really not that well for them either. For anyone coming from the North or West of Boston, it's way out of the way. For people coming from the South it's not all that great since, if they want to get to the outer Cape, e.g. Provincetown, it's a pretty long shot at 121 miles, 242 miles round trip. Charging in P'town or anywhere on the outer Cape is very difficult so, like other "end of the world" places, the round trip mileage seems like the best metric.
If instead, it were at intersection of 495 and 95 in Mansfield it would only be 108 miles to P'town and would be very helpful for people coming from the North or West on 495 or 95. It would only add 5 miles or so for people coming up from NYC compared to 195 out of Providence and they'd avoid Fall River and New Bedford.