I was trying to connect a wifi adapter to a raspberry pi today but the pi’s usb ports could not supply enough current to the device. A powered USB hub would be the ideal solution to this problem but I didn’t have one handy. The workaround I used was cut open the cable, strip the insulation of the red and black power wires and attach separate wires so that a power supply could be connected.
Here is the cable split open: ( I cut one of the wires by accident then re-soldered it and put heat shrink on it)
Then strip the insulation of the red and black wires and solder on the external power wires: