Apparatus comprising an electronic device such as an electronic smoking device to be powered by a battery in first and second different modes that consume different levels of electrical power； and a part that produces a magnetic field such a permanent magnet, that is separable from the device in preparation for its operation. The electronic device is configured to detect changes in the magnetic field at the device and in response thereto, to change its mode. The magnet may be included in packaging for the device so that whilst in the packaging, the device is switched to a low power storage mode and automatically switches to an operational mode when removed from the packaging ready for use.
