Slid a battery on checked the power and inserted the USB adapter. Now I have a portable power socket to use with the batteries that already have.
Step 2: Cutting The Housing
I was pondering wether to wire a step down circuit from 18v to 12v but seeing that the adapters will take 12 - 24 volts I decided just to add a fused link.
I Started by cutting the top of the housing off just above where the trigger was.