I saw on the Tesla Motors website that the Supercharger is capable of adding up to 150 miles of charge to a compatible Model S in 30 minutes. If that is the max, what is the typical rate of charge? I ask this because I know that Lithium Ion batteries usually charge quickly, but the charge rate slows down as the battery becomes more "full". If I have 50 miles of range left in a Model S, how much range can I expect will be added by the Supercharger in 30 minutes? How does having 100, 150, 200 miles left affect this?