When your electric vehicle's battery is fully charged, current flow is automatically stopped so it won't cause damage to your car's battery.
Please be mindful of others when using public charge points. Most charging points are meant for charging, and not long term parking. Public charge points might have a time-based pricing model that encourages EV drivers to relinquish the use of the charger when the battery is full. Please note that you will in these cases be billed even after the battery is full, should you continue to occupy the charger.