Step 1: Get Car USB Charger
Got mine for $1
Step 2: Collect Parts
You'll need a few 9vt batteries(some dead and new) And old 9vt battery clip(or you can make one after opening an old 9vt for parts) Solder and a soldering iron A USB cable to test to a phone or other device. A volt meter for testing voltage and coonections.
Step 3: Disassemble
In order to get started unscrew the charger and open the case. Once open you can cut the wires to the tip of the charge that goes into the car cigarette lighter.
Step 4: Rewire
Now the red wire inside my charger was actually negative when I put a 9vt to it. So I de-soldered the spring and wire and connected the battery clip. Once I tested it, I soldered it.
Step 5: Salvage Battery Clips
Now with plies at the top and seam of a 9vt, pry apart the protective metal until you have exposed the top battery clip. Then clip the small metal strips from the cluster, leaving a battery clip. Do this until you have 3 clips seperated.
Step 6: Assembly Battery Circuit
The first two battery clips need to lay upside down and arranged so the circle(+) and Hexagon(-) are next to each other Like this. ---- ---- | + | | - | | - | | +| ---- ---- Then solder one connection + to - Next solder another clip so the + will be accepting a minus and vise versa. Like so - + ---- ---- | + | | - | | - | | +| ---- ---- Solder and the clip two 9vts to the circuit. Test and you shoulder get 18vt on you meter. If so test the charger connected. You should seeee the led light. Test your connections if not. Now test the output voltage by placing you positive lead to the first lead in the USB post from left to right. And the negative to the far right lead in the USB port. A 5vt cuurent should be seen.
Step 7: Reassemble
Now you can put this together how you wish I wanted to kind of keep the same plastics so I just melted a place for the battery clip so I could clip the circuit to the Two 9vts the clip on the USB charger to them. Superglue and J.B. Weld to seal and stabilized the battery clips together without worrying about the solder joints coming loose.
Step 8: Test Again.
I'm glad I did this before adding the super glue because my red wire for the battery clip came loose so I resoldered a stronger wire on the circuit board. I tested with my IPhone and was able to charge it at least 5% in a few minutes. Ill test it dead and see how long and how many 9vts for a full charge.