Automatic watches don’t have a battery but they are equipped with a mechanism so that they wind themselves. Additionally you can wind the watch manually by turning the crown of the watch.
The operation of an automatic watch
An automatic watch is also called a self-winding watch. When the automatic watch is fastened to the wrist it winds itself by the movements of the wrist and arm. This happens because there is a weight starting to move, it starts spinning and winding the spring.