====== Power reserve ======
**Power reserve** refers to the amount of time that a watch can run without winding.

Most watches can run 40 to 48 hours without winding. This is seen as sufficient for all-day wear and to still remain running in the morning.

If a watch has a particularly [[long power reserve]], this becomes a signature feature. Many of these feature a [[power reserve indicator]] and may use [[two barrel]]s or exotic [[silicon]] components to run longer.

Running time is restricted by [[mainspring]] technology. Longer springs tend to cause a watch to run faster at first, then much slower. This has limited running time without the use of a special regulation system, as with the [[A. Lange & Söhne Lange 31|Lange 31]] or the [[DeWitt Academia Tourbillon Force Constante]], by which the driving force of the mainspring is held continuously equal during the entire running time.

===== See Also =====
  * [[Power reserve indicator]]
  * [[Long power reserve]]


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