The power reserve indicator lets you know the winding state of the mainspring.
Before removing the watch from your wrist, observe the power reserve indicator to check if the watch has stored enough power to keep running until the next time you wear it. If necessary, wind the mainspring. (To prevent the watch from stopping, wind the mainspring to store the excess power that will allow the watch to run for extra time.)
Power reserve indicator
The continuous operating time of the watch may vary depending on the conditions of your usage (such as the number of hours you wear the watch or the extent of your movement while wearing it).
In a case where you wear the watch for a short period of time each day, observe the power reserve indicator to check the level of the remaining power. If necessary, manually wind the mainspring.
How to read the power reserve indicator
As shown in the diagram below, when the indicator is pointing near 40 or F on the scale, it is fully wound. As the mainspring unwinds, the indicator will move toward 0 or E.
The accuracy of a mechanical watch is affected by the winding amount of the mainspring. If the watch is used for a long time when the winding amount is 20 hours or less, stable accuracy may not be obtained. Therefore, it is recommended that the winding amount be between 20 hours and full winding when you use the watch.
Once the mainspring is fully wound, it will slip if you wind it further, so there is no chance of the mainspring breaking even if it is over wound.
The indicator may move beyond 0 or E, but this is not a malfunction.
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The Power Reserve Indicator |
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The winding state of the mainspring |
Fully wound |
Half wound |
Unwound |
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The number of hours the watch can run |
Approximately 41 hours |
Approximately 20 hours |
The watch either stops or is running down. |
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Designs vary depending on the model. Refer to the above diagram to read the approximate continuous operating time.