Instead of opening the wall wart, why don't you just cut the USB cord in half and then buy replacement ends off of someplace like eBay or Amazon? Then you'll have two chords one with a wall wart and then the other one that you can take in your car with you in plug into a USB port in there or just wire it internally getting your need for soldering out of your system, LOL to a 12 volt cigarette lighter charger for automotive and you'll have two hard-wired Chargers.
One to go and one to stay LOL