Understanding power reserve and an unexpectedly early stop

Power reserve measures running time from a defined energy state to stopping. It helps with watch rotation, but winding level, complications and condition must be considered before comparing numbers.

The starting point matters

A stated reserve generally assumes sufficient winding. Briefly moving a watch taken from storage is not an equivalent starting condition. Confirm the exact movement and version, and note whether the stated test conditions are explained.

Running time and timekeeping are separate observations

Amplitude and rate may change toward the end of the reserve. A watch that is still running is not necessarily in its most stable operating range. Compare the first day, later days and the period before stopping, rather than observing only the final stop.

A useful home observation

Wind according to the instructions, note the start time and leave the watch in a stable environment without topping it up. Record whether functions such as the chronograph are running. This is not a laboratory test, but consistent conditions make changes in the same watch easier to interpret.

Common misunderstandings

A larger reserve figure does not guarantee better accuracy, durability or serviceability. Mainspring design, frequency, dimensions and other choices involve trade-offs. A clear decline from the watch's own previous performance is more informative than an isolated comparison.

Your practical checklist

• Start with sufficient winding.
• Record additional loads such as a running chronograph.
• Compare the same watch under consistent conditions.