electrongeek
Metrology Fanboy
If that existing 120V outlet on the outside of the house is the only one on that circuit, it can easily be rewired as 240V going to a NEMA 6-15 outlet. This is a simple re-wire at the load center, it has the hot wire going to one 20 amp breaker on one phase, and the former neutral wire going to a 20 amp breaker on the opposite phase in the load center. Since the circuit is still only carrying 12 amps, the existing wiring is fine. You just need the 240V specific 6-15 outlet. This will give you 11 mph charge rate. An electrician could do this for you very easily and cheaply - theoretically.
If the wiring for that circuit is actually rated for 20 Amps, you could install a 6-20 outlet and charge at almost 14 mph while drawing 15 amps.
The bug in the ointment is that any other 120V outlets on the same wiring circuit would also need to be converted to NEMA 6-15 or 6-20 outlets and 240 Volts. That may not be a viable option for you.
If the wiring for that circuit is actually rated for 20 Amps, you could install a 6-20 outlet and charge at almost 14 mph while drawing 15 amps.
The bug in the ointment is that any other 120V outlets on the same wiring circuit would also need to be converted to NEMA 6-15 or 6-20 outlets and 240 Volts. That may not be a viable option for you.