If you're on a road trip and find that you forgot your car charger for your phone or other USB device, Popular Science shows off how to make one on the fly using a USB cable and any 5-volt car cigarette lighter adaptor.
The process is incredibly simple. All you need to do is cut the USB cable, and strip the insulation to reveal a red and black wire. Do the same to the cigarette lighter adaptor. Finally, twist the black wires together, then the red, and wrap some tape around them to insulate them. When you're done, you've created an emergency car charger that works just about as well as anything you'd purchase at a store.
Hack Yourself An Emergency Car Charger [Popular Science]