Is it possible to split micro USB to USB cable so two cables (data + and data -) go to the PC with USB and two other power cables go to power brick?


Yes, but not quite what you suggest.

You would have to feed D+/D-/GND to the PC, not just D+/D-. This would allow the PC to communicate without supplying power.

It's then possible to split off the +5V cable and GND to an external +5V power supply. In order to do this, you would need to split open the cable where you want to splice off your power supply, preferably without damaging the D+/D- cables as these are controlled impedance and don't particularly like having random bits of cable or solder joints in them.

Once the outer insulation is split open, you can remove a small section of insulation from the GND cable and solder on the GND from your second cable. Then also cut the +5V cable and solder it instead to your second cable.

Finally, carefully cover everything up with heat shrink tubing or similar.

Basically you would have something like:

Cable Splicing

Image Source

  • \$\begingroup\$ So you are telling me that I would have to make two cables from one GND and then connect one half to PC side and the other one and +5V to power supply? \$\endgroup\$ Feb 21 '16 at 16:54
  • \$\begingroup\$ @CarlJohnson if you take a standard USB cable and leave the D+/D-/GND cables intact, then you can splice on your the GND cable for your supply to the existing one by soldering it on. See my edit \$\endgroup\$ Feb 21 '16 at 17:02
  • \$\begingroup\$ So I take off the isolation from GND from the cable I will use for data and cut the +5V then solder GND from power supply to the existing GND from data cable (that was not cut) and solder +5V to the micro USB side of data cable and it should charge from power supply and be able to exchange data with PC? \$\endgroup\$ Feb 21 '16 at 17:10
  • \$\begingroup\$ @CarlJohnson yes. \$\endgroup\$ Feb 21 '16 at 17:13
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    \$\begingroup\$ @CarlJohnson If you cut the data cables, you may have screwed up their impedance which basically will render the cable useless. Also if you have made it much longer that may make it so lossy that it is rendered useless as well. You could try adding a 1k or so resistor between the 5V pin of the USB port (the end of the wire that was disconnected) to GND and see if that helps - the port may require a small current draw in order to register the device is there (unlikely, but possible). \$\endgroup\$ Feb 21 '16 at 20:43

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