A system comprising a battery-powered device and a power supply for one or more battery-powered devices, the power supply comprising: a power input ; and an electrical output connected to the power input ; and the battery-powered device comprising: a power input providing power to the device ; a housing having an opening for receiving a smartcard ; at least one electrical contact within the housing, the at least one electrical contact being connected to the power input of the battery-powered device ; and wherein the at least one electrical contact is further configured to electrically connect to at least one conductive pad on the surface of the smartcard introduced into the opening of the housing; and characterised in that the power supply further comprises one or more protrusions , each having at least one electrode connected to the electrical output ; each protrusion of the one or more protrusions of the power supply is configured to enter the opening of the battery-powered device , the at least one electrode of each of the one or more protrusions is configured to provide electrical power from the power input of the power supply to the at least one electrical contact of the battery-powered device to provide electrical power to the battery-powered device , and the at least one electrical contact of the battery-powered device is further configured to electrically connect to a protrusion of the one or more protrusions of the power supply introduced into the opening of the housing. the power supply comprising: a power input ; and an electrical output connected to the power input ; and a power input ; and an electrical output connected to the power input ; and the battery-powered device comprising: a power input providing power to the device ; a housing having an opening for receiving a smartcard ; at least one electrical contact within the housing, the at least one electrical contact being connected to the power input of the battery-powered device ; and wherein the at least one electrical contact is further configured to electrically connect to at least one conductive pad on the surface of the smartcard introduced into the opening of the housing; and a power input providing power to the device ; a housing having an opening for receiving a smartcard ; at least one electrical contact within the housing, the at least one electrical contact being connected to the power input of the battery-powered device ; and wherein the at least one electrical contact is further configured to electrically connect to at least one conductive pad on the surface of the smartcard introduced into the opening of the housing; and characterised in that the power supply further comprises one or more protrusions , each having at least one electrode connected to the electrical output ; each protrusion of the one or more protrusions of the power supply is configured to enter the opening of the battery-powered device , the at least one electrode of each of the one or more protrusions is configured to provide electrical power from the power input of the power supply to the at least one electrical contact of the battery-powered device to provide electrical power to the battery-powered device , and the at least one electrical contact of the battery-powered device is further configured to electrically connect to a protrusion of the one or more protrusions of the power supply introduced into the opening of the housing. <EOS>