Auto injector with charger safety

Provided is an auto injector (4) connectable to an electrical power supply comprising a cartridge receiver (300), an ejector member (202), and a housing (6) accommodating a battery (10) and a first electrical connector (12) accessible via a connector opening (14) for accepting a second electrical connector (18) of the electrical power supply. The cartridge receiver is configured to receive a cartridge (700) containing a medicament. The auto injector further comprises a blocking member (100) coupled to the ejector member. The blocking member is configured to move between a non-blocking position wherein the connector opening is not blocked when the ejector member is in the first ejector position and the cartridge has not been received in the cartridge receiver, and a blocking position wherein a connector opening is blocked when the ejector member is the second ejector position and the cartridge has been received in the cartridge receiver. The provided configuration of the auto injector reduces the risk of serious electric shocks for users as it is not possible for a user to connect an electrical charger to the auto injector while a cartridge is installed in the auto injector.