USB cable for your device
Any 5-volt car cigarette lighter adapter
Cut the USB end off the cable for your device and strip the insulation. You’ll use the black and red wires to connect to the adapter. Twist together the other two wires.
Cut off the end of the cigarette lighter adapter that does not plug into the cigarette lighter. Use the knife to strip the insulation to reveal the black and red wires.
Twist the two red wires together and the two black wires together. Wrap tape around the joints to insulate them.
Plug it in and charge up your phone in the car.
This project was excerpted from The Big Book Of Hacks: 264 Amazing DIY Tech Projects, a compendium of ingenious and hilarious projects for aspiring makers. Buy it here. And for more amazing hacks, go here.