An electronic vapor provision device comprising a battery assembly 8 and a vaporizer 24, wherein the battery assembly 8 comprises a power cell 10 and a computer 12, the vaporizer 24 is releasably connectable to the battery assembly 8 and the computer 12 comprises a computer processor 16 and a memory 18； wherein the computer 12 is configured to detect whether the vaporizer 24 is connected to the battery assembly 8 without use of the electronic vapor provision device by a user； and to substantially remain in a sleep mode until the vaporizer 24 is connected to the battery assembly 8.
