Computer fans vary in size and voltage requirements. Some fans, such as the tower cooling fans, operate at 12 volts while Central Processing Unit (CPU) fans may operate at seven volts. Computer fans can also be used for a number of hobby projects that are not computer related. Toy hovercrafts and toy water boat propulsion are the first projects that come to mind. Each of these projects requires wiring a computer fan to a battery.
Set the two lantern batteries side by side. Cut a 5-inch piece of electrical wire. Strip 1/2 of an inch of insulation off of each end. Connect one end of the wire to the negative terminal of battery #1. Connect the other end of the wire to the positive terminal of battery #2.
Strip 1/2 of an inch of insulation off of the red and black wires attached to the computer fan. Connect the red computer fan wire to the positive terminal of battery #1. Connect the negative wire of the computer fan to one of the terminals on the switch. Connect the other switch terminal to the negative terminal of battery #2.
Turn the switch to the on position. The computer fan should come on.