The Breitling Watch Source Forums

Hi All,

I am pretty new to the automatic watch world.

I recently picked up a Breitling Chrono Avenger. It was a used piece that was in very good condition. I have been losing about 2 seconds a day. In a week or two around 20 seconds. I never gaining time. Is this normal? Or is this a sign of service required soon. How do you know when to service the watch? Thanks!

The watch is certified to run within COSC specs of -4 to +6 seconds per day, so yours is within specs. In theory you could get it regulated to run slightly fast instead of slightly slow, but I would let it settle for a few more weeks first before doing anything.

A watch with generally tell you when it needs servicing - inability to maintain COSC accuracy and / or loss of power reserve. After around 7 years it is going to need servicing regardless because the oils inside will have broken down.

I realise that a slow running watch is more annoying than a fast running one (i.e. the potential to be late for things is worse than being early), but personally I would leave it as 2 secs a day (as Roff said) is well within COSC specs and I would rather have as few "invasions" into the case as possible. Plus you may find that a regulation may result in the watch being more seconds faster than it currently is slow - e.g. +4 or +6.

Personally I'd say leave it until the first service is due.

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Driver8

Site Moderator

They are called "interventions" Driver
But I think I know what you were hinting at

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"It is just a matter of time!"

A slight disconnect between brain and fingers there on my part I think!

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Driver8

Site Moderator

Well depending on who is doing it, sometimes "invasion" is a more appropriate term than "intervention"

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"It is just a matter of time!"

so the watch is indeed pre-owned and i believe it was bought in 2009 i don't have the papers on me right now as I am on business travel. But its been two to three weeks and I lost about 45 seconds.

So if we assume it's 2 weeks (14 days), then 45 seconds is 3.2 seconds a day. If it's actually 3 weeks, then that amounts to 2.1 seconds a day. Both of which are inside COSC specs.

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Driver8

Site Moderator

I see. so it is normal lets say to lose 12 mins in a calendar year - assuming 2 seconds loss a day. Just trying to understand if it is time for me to send it in for maintenance. appreciate all the advice guys!

Basically for a modern COSC rated mechanical watch, yes it's normal....., assuming the 2 second per day loss is regular and consistent of course. Depending on numerous variables including how you wear the watch the accuracy may fluctuate a fraction. Some days it may be -2 seconds, the next may be spot-on.

You also need to remember that there are 86,400 seconds in a day, which is frankly an enormous number. If a watch movement is 99.9% accurate, it's timekeeping will still be wrong by a minute and a half in one single day. COSC standard (i.e. -4/+6 seconds per day) represents an accuracy of 99.9977%, which for something as small and complex as a mechanical watch movement is nothing short of astonishing IMO. Bear in mind a mechanical watch uses no computer chips, no circuit boards, no quartz, just cogs, wheels and springs, so again I find that level of accuracy incredible.

If super-accuracy is what you are looking for you'll be far better off with a quartz model as ordinary non-COSC quartz run at around +/-2 seconds or there-abouts (or 99.9998% accuracy). Or if you want incredible near-dead-on accuracy, then go for a thermo-compensated COSC quartz equipped watch (i.e. Superquartz in Breitling parlance). They are accurate to +/-0.02 seconds a day. Or for ultimate accuracy (if a little bit of a cheat!), go for an atomic/radio regulated quartz watch such as an atomic G-Shock.

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Driver8

Site Moderator

Driver...thats an asonishing breakdown when you look at it. It is incredible what happens in those springs and gears.

Ok 2 second loss is actually pretty good. Like Roff said it's running well within cosc specs.

It is unreasonable to expect these watches to be as accurate as an atomic clock.

Strap it on and enjoy. The 2 seconds you lose a day will never interfere with your life unless you are in a race.

Good that someone spells this out periodically. I completely agree. When you think about it, that a mechanical watch might average +2 seconds a day is absolutely stupefying.

Wow never thought of it that way. Great points Driver8! I love my Chrono Avenger. Time to look for a brown leather strap to go with this bad boy!