Spring Drive reserve

[pickettt]

This is the second time I’ve noticed this; Minimal daily wrist movement keeps my Spring Drive topped up. Very efficient rotor, I guess. But picking up my Snowflake after not wearing it for a few (3) days, I find the reserve still isn’t exhausted. Not even close, really. I plan to wind it fully and let it stop to see what I get out of it. Is there something about Spring Drive that makes the mainspring more efficient somehow? Has anyone else noticed longer than advertised reserve?

[Dsmith1974]

Originally Posted by pickettt

This is the second time I’ve noticed this; Minimal daily wrist movement keeps my Spring Drive topped up. Very efficient rotor, I guess. But picking up my Snowflake after not wearing it for a few (3) days, I find the reserve still isn’t exhausted. Not even close, really. I plan to wind it fully and let it stop to see what I get out of it. Is there something about Spring Drive that makes the mainspring more efficient somehow? Has anyone else noticed longer than advertised reserve?

The magic rotor is efficient because it works rotating in either direction. A full charge is spec’d to last 72 hours. I haven’t actually timed it. Wouldn’t surprise me if it were better than this. Seiko tend to be very modest with their specs.


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[JeremyS]

The advertised power reserve is an average. Sometimes the actual power reserve is less; sometimes it is more. I think most watch companies error on the side of caution when representing the lower reserve. Seiko seems to fall into that catagory. My Spring Drive (SBGR003) also lasts a bit longer than 72hrs.

The mainspring Seiko uses in the Spring Drive is less powerful than the one used in the automatics. The SD requires less torque. That’s also why Seiko uses the “magic lever” winging mechanism in the SD and reverser wheels in the 9S movements. I vaguely recall reading the magic lever had some issues when it came to windong more powerful mainsprings.