I'm working on a project to connect a Finch bot to a Raspberry Pi, with a portable battery pack for power (the battery pack provides two USB type-A outputs). Normally, the Finch runs on a long USB cable from a computer, so it gets both power and data via its one type-B port. For this project, I need to provide data from the Pi, and power from the battery pack to the Finch. I want to avoid using a USB hub, if possible, because all relevant hardware must be mounted onto the Finch. So, could I split open some USB cables, and connect the data wires to a USB cable coming out of the Pi, and connect the power wires to a USB cable coming out of the battery pack (thus ending up with a kludgy Y-split cable)? It seems like if this were possible, the cable would already exist, but I haven't found one. Before I go nuts with the soldering iron, can I get some feedback? 
Is it possible to split a USB cable to take power from one source and data from another?
usb