A battery charger (20; 20A), comprising: a housing including a plurality of charging ports (25; 25A), each of the plurality of charging ports (25; 25A) configured to receive a battery pack; a power supply module configured to be electrically connected to a power source and configured to supply power to the battery charger (20; 20A); a controller configured to select one of the plurality of charging ports (25; 25A) that is to receive a charging current, and generate a charging signal to enable the selected one of the plurality of charging ports (25; 25A) to receive the charging current; and at least one protection circuit configured to receive the charging signal from the controller when the at least one protection circuit is in a normal operational mode, characterised in that the at least one protection circuit includes a first semiconductor switch and a second semiconductor switch, wherein the first semiconductor switch is configured to allow the charging current to be supplied to at least one of the plurality of charging ports (25; 25A) when the at least one protection circuit is receiving the charging signal from the controller, and wherein the second semiconductor switch is configured to prevent the charging current from being supplied to the at least one of the plurality of charging ports (25; 25A) when the at least one protection circuit is not receiving the charging signal from the controller; wherein each of the at least one protection circuit further includes a thermal fuse; a control resistor configured to be electrically connected with the second semiconductor switch, and positioned adjacent to and thermally coupled with the thermal fuse; wherein when the charging current is being supplied to the at least one of the plurality of charging ports (25; 25A) and the at least one protection circuit is not receiving the charging signal from the controller, the second semiconductor switch is configured to allow current to flow through the control resistor to heat up the control resistor such that heat generated by the control resistor is configured to open the thermal fuse. a housing including a plurality of charging ports (25; 25A), each of the plurality of charging ports (25; 25A) configured to receive a battery pack; a power supply module configured to be electrically connected to a power source and configured to supply power to the battery charger (20; 20A); a controller configured to select one of the plurality of charging ports (25; 25A) that is to receive a charging current, and generate a charging signal to enable the selected one of the plurality of charging ports (25; 25A) to receive the charging current; and at least one protection circuit configured to receive the charging signal from the controller when the at least one protection circuit is in a normal operational mode, characterised in that the at least one protection circuit includes a first semiconductor switch and a second semiconductor switch, wherein the first semiconductor switch is configured to allow the charging current to be supplied to at least one of the plurality of charging ports (25; 25A) when the at least one protection circuit is receiving the charging signal from the controller, and wherein the second semiconductor switch is configured to prevent the charging current from being supplied to the at least one of the plurality of charging ports (25; 25A) when the at least one protection circuit is not receiving the charging signal from the controller; wherein each of the at least one protection circuit further includes a thermal fuse; a control resistor configured to be electrically connected with the second semiconductor switch, and positioned adjacent to and thermally coupled with the thermal fuse;