Superchargers work at 400v DC and send digital information about the vehicle over the pilot line. So basically it would be difficult to steal from a supercharger.
You would likely have better luck with J1772 station if your charging unit can accept 240v AC.
That answers my question, supercharger seems out of the question, till somebody reverse engineers the communication protocol, and Tesla have anonymous or the same vehicle showing up at multiple charging spots. Does the J1772 have any authentication? Is there such a thing as a free charging socket?
J1772 uses an analog pilot, The vehicle communicates it is ready to charge when the pilot is pulled down from 12v to 6v with a 886 ohm resistor and diode.
Some charging stations are free and others have a fee and require a card/membership.
Say I have an eBike/DIY electric vehicle, how can I charge it for free?
I've had a look at the EVSE open source specs, and the various types of EV power connectors/adapters which may or may not trick a supercharging station into giving me free power. Obviously some power handling circuitry would need to down-volt down-amp to safely recharge a 48/72v LiPo/Li-ion battery pack.