Two years ago I got a Seiko Dolce wristwatch and set the time by calling 117 (official time in Japan), as suggested in the owner’s manual, which also said that accuracy should be within +/- 5 seconds per month. That sounded pretty darn accurate to me.
But a while later I noticed my watch was staying exactly on time. When I heard the chime on the radio or called 117, my watch was still keeping perfect time 5 months later. In Japan, many clocks are set to the official time–obsessively to the second. Now that I had a super-watch, I was getting obsessed too!
During winter it started to fall behind (about one second when I noticed it), so as an experiment, I reset it and kept in on my wrist to see if temperature affected it. Amazingly, it stayed within a second over the next 8 months. Then the battery went flat and I had it replaced. Now I think it is about 1 second fast every few weeks (I’m not obsessed enough to keep a log.) I wonder what affects the accuracy of a quartz watch, and why my watch’s accuracy is different now than before changing the battery, although it’s still pretty good. Battery freshness? Humidity in the watch case?
Hi akitaking and welcome to the boards. I have some experience with this because of my interest in celestial navigation and marine chronometers.
The main think affecting a quartz watch is temperature. Over many years I have kept track of many (cheap) quartz watches and chronometers. The important thing for me is not whether they run a bit fast or slow, the main thing is that they have a constant rate. If they do I can easily calculate the error. If kept a a fairly constant temperature most quartz watches are very constant with no more deviation than a second every month or two.
I have had some which would run fast or slow by as much as 10 seconds/month (unusual) but still very constant. Then i have found the odd one which, like yours, accumulates hardly no error.
Again, note that a constant rate is the important thing, much more than running on time.
several more things. yes, humidity and battery voltage will also affect. Also, I have found quartzs tend to age so the error rate slowly shifts over time until it settles somewhere.
i have records of some cheap quartzs going back many years. Now I do not keep them like I used to.
Note also that you have to account for the leap seconds which are occassionally added or subtracted at the end of each semester. if you do not take them into account you’ll be thrown off base.
Heat and cold will affect the time-keeping ability of a quartz watch. Quartz crystals, whose extremely steady vibrations are responsible for the unrivaled accuracy of quartz watches, are cut so they perform optimally at room temperature, says Fenwick. A temperature of 100 degrees Fahrenheit will throw the timing off by about 1 second a day, as will one of 32 degrees Fahrenheit.
The important fact to note here is that keeping the watch’s temperature constant will allow it to stay accurate. Fortunately, for wristwatches, this is fairly easy - the human body has a very accurate thermostat. Notice how, in the wintertime, when the episodes of exposure to cold outdoor air added up, the watch went off.
To help prevent this, you can wear your watch so that the body of the watch is on the inside of the wrist where the blood vessels are closer to the surface and thus make a better thermal contact with the back of the watch. Just be sure that you reset your watch after you recover from an extended fever.