In order for a an ATM, or other credit card reader, to detect the credit card code, it has to have some type of motor. Instead of needing a motor, like ones we built in class, all you need to do is swipe a credit card in a reader. The movement through the reader acts exactly like a motor. The swiping movement causes the magnetic field to become a current in the system, alowing the electronics to be picked up. If you do not "swipe" there will be no current giving you a "dead battery