How to charge my Ubuntu phone's battery off my Ubuntu laptop's battery?

When I plug my BQ Aquaris Ubuntu phone into my laptop running 14.04.3 LTS and shut down the laptop while the phone is charging the phone keeps charging...

Once I unplug the phone however, it doesn't charge any more after I plug it back into any of the the USB ports of the shut-down computer.

How can I continue charging my phone's battery off my laptop's battery?

_{I know: it's a bad idea as it'll drain the laptop battery, but this is an emergency and that's what I need right now! :P ;-)}

Solution 1:

Easy:

1. Turn on the laptop
2. Go to the BIOS settings (no need to fully boot the computer)

3. Make sure charging external devices during low power states is enabled (if the option is present)

   

4. Plug in the phone

5. Shut down the computer.

Now the phone will charge off the laptop's battery again!

If that doesn't work:

1. boot up the computer fully into Ubuntu and:

   sudo apt-get install acpitool
   

2. Do a:

   acpitool -w
   

   to see the ACPI capable devices

3. Then do:

   sudo acpitool -W iDevice
   

   where iDevice is the device you want to switch from *disabled to *enabled