Question for the tech experts (Cartier)

[Afterglow]

I have a Cartier Santos chronograph.
If I run the chrono 24/7 I understand that it in no way "wears" on the movement.
My question is would it reduce the power reserve?

Sorry for what may be a dumb question. I appreciate the help.

[Tools]

You cannot add "work" to a set power source and not have an affect on the power source.

Basic physics.

Also, when you kick in this additional work, you are engaging more gears and sub dials, so, yes, you are including those additional wear sources.

Run it if you want, but you cannot get something for nothing in the mechanical world.

[enjoythemusic]

Since you're asking for more energy from the mainspring, you reduce 'power reserve' when not worn.

[Gruesome]

You can't get more energy from the mainspring. The mainspring stores a fixed amount of energy in the fully wound state, and a different smaller amount in the fully unwound (but still inside the barrel) state, and the difference is what it delivers to the train in a fixed number of revolutions (=fixed time). The mainspring unwinding time is set when the movement is designed.

With the chrono mechanism engaged you need a slightly higher torque to keep the movement going, so as the mainspring unwinds and the torque decreases, the movement will stop a little bit earlier. You could choose to stop the chronograph mechanism at some point before that happens, and then get the exact same run time (power reserve) as you would have gotten had it never been engaged in the first place.

So, in that sense, the chrono mechanism does not rob the watch of anything. As long as there is sufficient torque to keep the escapement going, there is just a little bit less mainspring energy wasted on making things bounce harder and rotate faster, and instead goes into turning and advancing the chrono mechanism.