Solder a bit of solder to all stripped wires. USB and coil cable.
BEFORE you solder all the wires together two important things:
- Cut your pieces of shrink tubing and put them on the wires first!
- Once you have soldered one end, make sure that you connect the same colours to the same colours at the other rend too!
One thing that I forgot here is to add another piece of big heat shrink tubing BEFORE soldering so that I can over all the individual cables and truly link the two (USB and coil cable) together --> strain relief!!!