Exemplary power supply systems according to the present invention include circuitry that is configured to provide DC power and configured to receive a input signal that originates from a portable electronic device (the “PED”) and to provide a output signal to be sent to the PED. Such circuitry is configured to be coupled to the PED via a connector having a first, second, third, and fourth conductor. Such a connector is configured to be detachably mated with a power input interface of the PED to transfer the DC power to the PED, a ground reference to the PED, the input signal from the PED to the circuitry, and, in coordination with the input signal, the output signal from the circuitry to the PED, which is usable by the PED in connection with control of charging a battery of the PED based on the DC power provided by the circuitry.