Have any of you had experience with DC Fast Chargers (480V)? I heard they can charge your vehicle in less than 30 minutes. If you have used them, how long did it take to get a full charge and what does it cost? Are there some locations that allow you to use for free? Seems like there aren't very many out there and if so are they available or do you have to wait in line to use it? How do you find them?