A battery is a device that, when charged turns Electrical Energy into Stored Chemical Energy. Then when it is in a complete circut, such as a circut to power a lightbulb, it turns that Stored Chemical Energy Back into Electrical Energy which flows along the wires to the lightbulb which converts the Electrical Energy to Light and Heat Energy. in a circut with a motor instead of the light bulb when the Electrical Energy flows through the wires to the motor the motor converts the Electrical Energy into Mechanical energy to power itself.