Highly functional, the power reserve indicator is useful for everyday use. It converts a watch's remaining energy into time. Here's everything you need to know about this complication!
What is the power reserve?
Applied to parts that draw their energy from the tension of a spring, the power reserve is an essential element of mechanical watches, whether manually or automatically wound. This function determines how long the mechanism can continue to operate without being wound or worn.
The duration of the power reserve varies from ten hours to several days from one model to another. The average is around forty hours of autonomy, and when it runs out, the watch stops. An extended power reserve is highly prized by collectors, particularly those with a calendar timepiece, as it enables them to keep their movement wound at all times. In order to provide users with the best possible information on remaining power, the major watch manufacturers offer models equipped with this type of indicator.
What is the purpose of this indicator?
Thanks to the display of this complication, users of a manual watch can assess the right moment to wind it. Not too early, when it still has sufficient autonomy, nor too late, when it has already stopped. Driven by the movement of the wrist, an automatic watch winds itself. In other words, it wouldn't a priori need this complication. However, the power reserve display is useful for owners of several automatic timepieces who tend to alternate between them.
Whether the watch is manual or automatic, the power reserve indicator appears either on the case or on the dial. The most common display is by means of a hand running along a circular arc from + to -, or graduated in hours or even days. The display can also be linear. In this case, a cursor moves along a graduated segment. Finally, it can be displayed via an aperture revealing a more or less significant portion of color, depending on the reserve level.
