The guidance for how to store an EV for an extended period of time varies between manufacturer and vehicle, so we would suggest consulting the owner's handbook for any specific guidance. As a general rule we would advise charging the main vehicle battery to at least 50% to ensure it does not discharge completely during the time it is left parked. You may wish to consider using a trickle charger on the 12V battery to ensure this remains functional also. EV batteries should ideally be stored between 20% and 80% rather than 100%, so unless you can remotely control the state of charge while you are away it may be better to leave the vehicle unplugged.