A power supply unit includes a plurality of the interface ports and a plurality of power delivery units, each coupled to one of the interface ports and configured to extract power from data signals communicated over the interface ports by remote devices. A sharing circuit is coupled to each of the power delivery units for generating a power supply voltage from the power extracted from the data signals. A controller is configured to generate a communication line power loss estimate for each of the interface ports and configure the power delivery units to balance amounts of power supplied by each of the remote devices based on the communication line power loss estimates.