What would cause a quartz watch to suddenly not keep time properly?

[Rave]

A bit of a random query, but I know we have a lot of scientists and watch enthusiasts here.

For my 30th birthday my brother and my sister-in-law got me a really nice watch- an analogue Lorus with a perfectly proportioned stainless steel case and wristband, and a really attractive deep blue face. It suits my classic, understated style perfectly. And for the first 18 months it was quite incredibly accurate- it would lose about 5 seconds a month against my radio clock. I'm a bus controller, and my job is to know the time very accurately when I'm giving buses intructions (no really- 30 seconds makes a difference when you're dealing with a route that runs a bus every four minutes during peak hours).

Since I came back from my holiday in Lanzarote though, it's been getting slower and slower, to the extent that it's now basically useless- it's lost 3 minutes in the last 24 hours.

The obvious thing to do would be to change the battery- but I assume it's got a Lithium coin cell in there, and AFAIK the voltage of the battery should make no odds to how fast a quartz crystal vibrates. As it's a sturdy thing, waterproof to 100m, it looks as if you need a special tool to get the back off.

Again this is probably tighness getting the better of me, I daresay it'd cost less than a tenner to get a jeweller to change the battery. But I don't want to drop that cash unless I'm very likely to get back the extremely accurate watch I used to have. Otherwise I might as well dig out one of the other fairly accurate watches I still have.


Thoughts please.

[CAT-THE-FIFTH]

Again this is probably tighness getting the better of me, I daresay it'd cost less than a tenner to get a jeweller to change the battery.

The main issue is whether the watch still maintains its full watertightness after replacing the battery.

IMHO,one of the Citizen Eco-Drive or Seiko Kinetic watches tend to work out cheaper.

[Mama Sumae]

Since I came back from my holiday in Lanzarote though, it's been getting slower and slower, to the extent that it's now basically useless- it's lost 3 minutes in the last 24 hours.

Perhaps the good weather is tricking it to believe its still in Spain? (you said the useless bit not me )

Seriously now, I hardly know anything about watches but a quartz watch basically uses a crystal oscillator cut and designed to generate a particular steady frequency through a process called Piezoelectricity (that's me flexing my e-brain btw). To my best knowledge and I am sure I am soon to be corrected, unless you change its physical properties or external stimulation (if you would like to call it so) it will continue to operate steadily (neglecting changes caused by temperature variation and so forth).

Now on a watch the battery provides the juice for this "external stimulation", and even though these oscillators are quite sturdy in operation at end of the battery's life (when the battery falls outside the specified voltage ranges) the watch accuracy is sure to suffer (how else would you know you need to change the battery ). If the issue is indeed the battery, might not well be, properly replacing it would bring your good old watch back (I know it has to me in the past) but notice I said properly replacing.

Replacing a battery on cheaper watches is rather straight forward but more expensive ones often regulate themselves and need to have its battery replaced by properly trained monkeys (with all due respect to the craft and craftsman). Is it worth it? I guess it depends on the particular watch and how much you value it yourself, anyway you will surely get better advice than mine regarding this (I didn't even consider water-tightness and so forth).

[kalniel]

An inaccurate watch is almost worthless to you, so if it's rescued by a £2 market stall battery change then you're up, if not, you've not lost much. They usually have the tools for most watch backs. Or you could go to a jewellers and get it 'serviced' - while not something you'd like to throw money on, it's cheaper than a replacement watch.

[Flibb]

I have a caseback removal tool and should be able to do the battery for you (as long as its not really odd), although the postage to me and back would probably be more than getting it done locally. I do batteries on most of my own quartz watches, apart from one that I keep pressure tested for mucking around in water.

Problem with solar and minetic watches is that the storage cell / capacitor dies, lat one I replaced went after 5 years. Some of my battery powered watches can last longer than that.

[Lucio]

One other thing to consider, if it's not the battery running down, then some sand or grit could get caught inside the mechanism. Whilst the water resistance makes it unlikely, it's a possibility that it's been compromised.

[Tumble]

Mine has a thing where when the battery starts dying, it counts every 4 seconds instead of every one. Lost a bit of time - maybe 30 seconds every 24hrs until I got the battery replaced. You might want to give this guy a ring: http://www.h3-watches.co.uk tel: 01425672082. He does servicing on Traser watches, but I'm sure he could do yours if it's just a battery. He resealed mine and pressure tested it and everything, new glass & bezel & a clean for £45 inc. postage. It was 3 days away - which is phenomenal service from here.

[GoNz0]

dunno why you think a battery wont casue a watch to slow down. just get it changed and be done with.

just because its 18 months old doesnt mean its battery is

[Flibb]

Just had a quick look and some adds list Lorus as having a 2 year guarantee. I would expect the battery to last longer than 18 months from purchase, although as Gonzo pointed out it could have been sitting on a shelf a lot longer.

[Butcher]

The obvious thing to do would be to change the battery- but I assume it's got a Lithium coin cell in there, and AFAIK the voltage of the battery should make no odds to how fast a quartz crystal vibrates.

The crystal frequency is effectively fixed by the geometry of the crystal but the timekeeping is more than just the crystal. When the battery is running low, even if the crystal is vibrating at the correct frequency the battery won't have enough energy to move the mechanism for every vibration, so it will start to skip oscillations and lose time.

[listy]

take it to a jewelers get them to change the battery and they might see if it has some dustor somehting in it should cost under 5quid if its a normal battery

[scaryjim]

Sounds near-identical to the watch I have. My original battery lasted ~ 3 years. When it went I took it to one of those little watch battery stalls you get all over the place and it cost me about a fiver to have the battery replaced. The replacement has just gone, but then it's been well over 2 years so I think that's probably unsurprising. Must get round to replacing the battery again some time

[Tumble]

I got my watch in 2001. It's on it's second battery which was replaced 18 months ago I like my watch.