Automatic watches are charged by movement. These watches do not contain batteries. By moving the watch as it is worn on the wrist, power is stored within a spring in the watch. When fully charged, the power reserve usually lasts for approximately 38 hours. If an automatic watch is fully charged and then not moved, it will run out of charge and stop in 38 hours.

When an automatic watch stops completely after running out of charge, it should be 'initiated' by winding it manually. This means turning the crown clockwise approximately 10 times, or until it starts to feel tight. If an automatic watch is not initiated after stopping, it may run out of charge, slow down, or keep stopping and starting.

Always re-initiate your automatic watch after it stops completely.

The amount of an automatic watch is charged can be increased by wearing a tight fitting strap - so the internal parts of the watch move and charge the movement, rather than having just the watch itself moving.

It should also be noted that automatic watches are generally not as accurate as quartz watches. It is not abnormal to notice time variances of -10 to +30 seconds per day. More expensive models, e.g. Tissot valjoux movement watches, will have a greater degree of daily accuracy.