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Discussion Starter · #1 ·
Hello-

Bought a brand new seamaster 300M diver three months ago from an Authorized Dealer. I noticed that on a full wind of beteeen 60-70 rotations I was only getting 37 hours of power reserve. Tested it 3 times over 6 days and each time I got 37 hours and not the 48 it should get. I sent it back to Omega and they said the movement is within factory specs and that they are getting 48 hours and no new parts were put in they say.

I am am wondering how they are getting 47-48 hours and I only reached 37 hours each time I fully wound it and took it off to sit so I could test it. They have not sent it back yet but are supposed to this week. Now I feel like my brand new watch had “surgery” on it all to find nothing. Thoughts?
 

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"The force that the mainspring delivers as it unwinds is not uniform in nature. If you wind a watch up all the way, the force delivered will be slightly higher than at the end of its wind. The reason for this is Hooke's law. “Ut tensio, sic vis” (Latin) or “as the extension, so the force.” When a mainspring is wound all the way, the extension of its outer coils is large in comparison to its inner coils. Because of this, the delivered force is larger at the beginning of its unwinding than it is close to the end. (If you've ever watches a wind-up toy gradually slow down as its spring unwinds, you've seen this phenomenon yourself."
https://www.hodinkee.com/articles/a-close-look-at-constant-force-in-watchmaking

https://www.watchuseek.com/f6/does-2892-movement-run-slower-runs-down-651086.html This touches on it a bit, but focuses more on accuracy as a mainspring runs down. I've heard that a chronograph movement will not run as long and stop with the mainspring partially coiled up, because as the spring opens/winds down, it doesn't have enough force to power the basic time keeping function, and extra gears of the chronograph timing mechanism.

Could be that when the mainspring uncoils, at the very end of uncurling it doesn't have enough torque/force to fully uncoil and power all the gears. So it may stop partially coiled up, and this could be where the last 10 hours are left, in a partially coiled mainspring.

When the watch stops, have you ever picked it up and given it a light tap, or even just moved it? If so, has it run for any amount of time?

Other possible cause might be too much friction from improper lubrication (but factory just took a look at it, so seems unlikely), what position do you vs the factory lay the watch in to run down? Assuming it would be just on a flat surface dial facing up, maybe the factory puts it at an angle which may affect the watch's operation?

Then again, maybe someone else can chime in and diagnose a problem in the watch itself, but would hope that would have been caught by QC at the factory twice now.
 

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Discussion Starter · #3 ·
Thanks for your reply. I understand about the mainspring delivering more power at the beginning than at the end of the wind. But why am I getting 37 hours of power reserve laying it one time face up and another time on its side and Omega says they got 47 hours when they tested it? The first thing that I will do when I receive the watch back from Omega is to fully wind it and see if I get the 48 hours of reserve which I doubt I will get. Had they put in a new mainspring then I would believe I would get a longer reserve but they said it needed no new parts. The watch is only 3-4 months old. Now even when I get it back I will have no confidence in the watch anymore.
 

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No new parts may just mean some additional lubrication, screw undone and tightened again, things fit together better the second time around. Being a co-axial, there should be even less friction compared to other models.

https://www.watchuseek.com/f2/automatic-power-reserve-what-normal-806771.html

It's a bit of a tough pill to swallow, especially when you bought it brand new, you expect it to work as described perfectly. I hope you get it back and it keeps great time, the power reserve is much better and it doesn't bother you.

Personally, I don't think I've ever timed one of my automatic watches power reserves. I had one stop on my wrist, bought used, so knew it needed a service (probably why the guy sold it, but came back brand new).
 

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Hello-

Bought a brand new seamaster 300M diver three months ago from an Authorized Dealer. I noticed that on a full wind of beteeen 60-70 rotations I was only getting 37 hours of power reserve. Tested it 3 times over 6 days and each time I got 37 hours and not the 48 it should get. I sent it back to Omega and they said the movement is within factory specs and that they are getting 48 hours and no new parts were put in they say.

I am am wondering how they are getting 47-48 hours and I only reached 37 hours each time I fully wound it and took it off to sit so I could test it. They have not sent it back yet but are supposed to this week. Now I feel like my brand new watch had “surgery” on it all to find nothing. Thoughts?
Are you sure you are fully winding it? When it's fully wound using the crown you can sometimes hear additional clicking from the mainspring slipping in the barrel if you hold the watch to your ear. I would suggest trying the test again when you get it back, but wind the crown 100 times if you have to in order to make sure it's fully wound. Then lay it dial up and see how long it runs.

Note that Omega is using a test winder to wind the watch, rather than winding it using the crown, but that should not matter.

Cheers, Al
 
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