Step 1: Objective
For my phone, a 1Amp charger was enough, but you can use any that fits.
Step 2: Materials and Tools
A 12 v plug in USB charger 1A or greater
Fuse splice kit to suit your vehicle
Additional 2Amp fuse
Insulated wire - 16-18gauge
Of course you need a car preferably with a blanked switch housing where you want your power supply. Mine is a 3rd generation 4 runner.
Soldering iron and solder
Dremel - engraving and sanding bit, cutting wheel
Drill- 1/16drill bit
Hot glue gun
Step 3: Dissassembly
Undo the front screw and put aside the face plate.
Undo the metal band , open the housing and take the board out. There is usually a spring or fuse connected to the + terminal. The negative terminal are the metal straps that compress in the outlet if the plug were used as it should.
Remove the switch blank from the car and put aside.
Step 4: Measure Up and Cut
Use the USB circuit behind the blank to check for fit.
Once determining it can work, mark out cuts on the face plate so it mounts on the back of the switch plate.
Cut USB faceplate so it fits snug against the back of the switch blank.
Trim the blank where needed, but keep within the outer raised edge of the blank, keep in mind where the faceplate mounting screw goes.
Mark out the opening for the USB, led light if you have one and the faceplate mounting screw. The faceplate acts as a stencil , so it should be easy .
I screwed the face play to the back of the switch for ease, but you can remove it after marking.
Using the dremel trim out the plastic from the back. Do not go straight through , but get as close to it as you can.
Drill out holes for the led and faceplate screw.
Remember the head of the screw is small so keep the tolerance tight.
Mount plastic backing to the faceplate and trim housing to allow it to fit behind the switch blank.
Offer it up for fit on the car.
Step 5: Wiring
Solder wire from the ground (-) the springy bands or the - terminal on the board. I removed the springs altogether and went straight to the board
Solder wire to the (+) terminal on the USB board. The pointy end of the charger.
Reassemble the housing with the switch blank in place.
Using the fuse splitter - install the 2amp fuse on the tap.
Find the accessory fuse on the inside fuse panel. You can u do the battery terminals , but it's not really necessary.
Connect the (+) wire from the charger to the fuse splitter . Do not plug in to the fuse box !!
Connect the (-) wire to ground - any bolt or score that firmly tightens to the body of the car will do. You may need to have spare wire to reach an inconspicuous place, I used the bolt just under the fuse panel.
Make sure there are no exposed wires on the (+) connection!!!!
Find the accessory (acc) fuse. With the keys out of the ignition, pull the fuse and install it in the fuse splitter.
Plug the splitter in place on the fuse panel.
Double check your wiring, once your comfortable - adda bit of hot glue to stick the housing to the back and seal up the wiring coming out of the USB housing.
Turn the ignition to acc- your USB should work. If it doesn't - check the wiring .
If it does - pop in the USB switch blank and enjoy your work!
Disclaimer : I am not responsible for any damages caused by doing this mid - intended or otherwise. Proceed at your own risk!