A power management device for controlling a delivery of a DC-power from an external DC-power supply device, wherein the external DC-power supply device operates at least in a powered-device detection mode wherein the external DC-power supply device detects whether an external DC-powered device is connected, and in a powered-device operation mode wherein the external DC-power supply device provides DC-power to the external DC-powered device, the power management device comprising: - a power interface unit configured to receive DC input power from the external DC-power supply device and provide DC output power to the external DC-powered device in an accepting operational state of the external DC-powered device; wherein the external DC-powered device is operable, in accordance with a predetermined power-acceptance criterion, in either the accepting operational state wherein the external DC-powered device is detectable and receives DC power from the external DC-power supply device or a non-accepting operational state; wherein the external DC-powered device is not detectable during the operation in the powered-device detection mode, - a power-acceptance decision unit which is configured to determine whether or not the power-acceptance criterion is fulfilled and, in case it is fulfilled, to provide a power-acceptance command to the external DC-powered device and indicative of an instruction to operate in the accepting operational state; - a voltage-level comparison stage connected to the power interface unit and configured to deliver a switching control signal with a respective signal state indicative of a DC-voltage amount currently supplied by the DC-power supply device; - a switching unit, which is configured to receive the switching control signal and to mutually connect, when the signal state of the switching control signal indicates that the DC-power supply device is currently operating in the powered-device detection mode or in the powered-device operation mode, the power interface unit and an energy storage unit that is configured to store electrical energy currently received from the external DC-power supply device via the power interface unit. - a power interface unit configured to receive DC input power from the external DC-power supply device and provide DC output power to the external DC-powered device in an accepting operational state of the external DC-powered device; wherein the external DC-powered device is operable, in accordance with a predetermined power-acceptance criterion, in either the accepting operational state wherein the external DC-powered device is detectable and receives DC power from the external DC-power supply device or a non-accepting operational state; wherein the external DC-powered device is not detectable during the operation in the powered-device detection mode, - a power-acceptance decision unit which is configured to determine whether or not the power-acceptance criterion is fulfilled and, in case it is fulfilled, to provide a power-acceptance command to the external DC-powered device and indicative of an instruction to operate in the accepting operational state; - a voltage-level comparison stage connected to the power interface unit and configured to deliver a switching control signal with a respective signal state indicative of a DC-voltage amount currently supplied by the DC-power supply device; - a switching unit, which is configured to receive the switching control signal and to mutually connect, when the signal state of the switching control signal indicates that the DC-power supply device is currently operating in the powered-device detection mode or in the powered-device operation mode, the power interface unit and an energy storage unit that is configured to store electrical energy currently received from the external DC-power supply device via the power interface unit.