The chronograph should not impact the timekeeping...

Roff if you have a second could you please explain this. To me, I would think, that simply by introducing additional wheels/cogs etc. in the form of the chrono function, it would have to at least slow the timekeeping down a bit just by adding additional friction. Is there some way that a watch compensates for the additional drag of the extraneous gears (if you will) that allows it to keep normal time without fluctuation? Is there some compensation mechanism?

Thanks,

Elwyn

If the watch is running correctly the mainspring is applying force through the running train that is being controlled by the excapement. The balance wheel is ultimately subjected to this force through the running train via the pallet fork, but the hairspring applies force to the balance wheel to counteract the force of the running train and accuracy is maintained by the hairspring maintaining the frequency of the balance wheel.

What the chronograph essentially provides is a way of displaying the total movement of the fourth wheel (minute wheel) for a certain amount of time - effectively engaging the central seconds hand with the fourth wheel - it's not a whole new set of gears.

So if I understand that correctly, even though the fourth wheel (chronometer) is engaged, and would cause an increase in resistance to the movement and potentially slow the watch, the hairspring compensates for that potential retardation in the frequency of the balance wheel, and by doing so keeps the watch accurate.
Correct?

More or less - the fourth wheel is already part of the running train anyway, the chrono simply engages the totaliser for that wheel.

But doesn't engaging the totaliser add some resistance or is this compensated for by the action of the hairspring?

so why if you test a watch into the chronocomperator with the chronograph function enabled the watch significantly slow?

I would need to see the specifics of that - in a properly adjusted watch the chronograph should have no noticeable impact - think about it, the watch would be rather useless as a chrono if it messed up the accuracy.

i correct myself maybe i didn't understand well, the watchmaker tests the watch with chrono disabled and then with the chrono enabled... so i thought maybe is to test the watch moving slow or not... confused.

I would need to see the specifics of that - in a properly adjusted watch the chronograph should have no noticeable impact - think about it, the watch would be rather useless as a chrono if it messed up the accuracy.

Chronograph will likely reduce the power reserve by 6 - 8 hours, but that behaviour is not normal.

The chronograph should not impact the timekeeping, it sounds as though something is 'dragging' in the running train - get it to the AD to be sorted under warranty.

I just purchased a B01 as well and yes I am have the same problem. The watch keeps excellent time +-1 second per day but when I activate the chronograph, it looses the following: 6 seconds after 20 hour, 19 seconds after 35 hour, 27 seconds after 40 hours and stops after 46 hours. These test where done while the watch was at rest on table after I manually wound the watch-up (42 tuns).

What is your recommendation on this one, insist it be returned back to Breitling for service, have the AD have one of his watch repair persons fix it(this is what they recommend), simply live with it.

I simply don't want just anyone to open the watch up and temper with it.