I never manually wind my automatics so I have never tried to fully wind my Must XL. Without a power reserve indicator the only way to know if you have fully wound a watch is to feel resistance to winding, and since getting to that point you risk overwinding and breaking the mechanism (a lesson from my teens) I just let my winder or my arm do the winding for my autos and never get close to full wind on my manuals. However, I have left it off the winder (I have 15 autos and 14 winders) for over 24 hours probably close to 30 hours after wearing it for a day and it was still running. I would guess it meets the 40 hour PR specified.

 

Last Friday, on a long weekend vacation, I purchased a Cartier Tank Must XL Automatic. It's my first and probably only Cartier (gratuitous pic below). I wore the watch exclusively over the weekend and really enjoyed everything about it. When I got home on Monday, I gave the running watch about 30 turns of the crown, set it to my local time, and added it to the watch box. I have gotten in the habit of winding all my watches every day, and on Tuesday when I set out to wind my watches, the Cartier had stopped at about 2PM on the same day. I figured it just didn't get a full wind, so I gave it about 60 turns and set the correct time. Today, when I set out to wind my watches, the Cartier had stopped again shortly after 2PM. I gave it about 90 turns and set the correct time. I will see if it is still running after work tomorrow.

* UPDATE * After 90 turns yesterday afternoon, the watch was still running after work today.

Am I missing something? Does the 1847 MC movement have a power reserve of less than 24 hours? Does it require more turns of the crown to get to full power than a typical movement? Is there something wrong with my example? It ran flawlessly while I wore it over the weekend without any manual winding.

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It has been my experience that it is sometimes not unusual to get a new watch to fully function properly, meaning the power reserve. More often than not it takes a good winding (fully wound) for it to get it to settle in. I have had this happen before with other brands. I suspect that w/90 turns, you had it fully wound but I would wind it to the max again just in case. I bet you will find it will settle in if it hasn't already. I was lucky w/my Tank Solo XL. It took off right out of the box and has been consistent ever since.. Congratulations on your new Must XL. By the way, the 1847 movement is nothing more than an in-house evolution of the ETA 2824 which was the previous movement used in this watch and no, it does not have a short power reserve----less than 24 hours!!! You should find that the power reserve is at least 48 hours and quite possibly a bit more. Love your Must XL!!!!

 

Thank you. It's unlike any watch I've had before. It is running as expected the past couple days. I appreciate your response.