jamesam wrote: ↑Fri Jul 16, 2021 8:16 pmIf the discussion has moved to battery replacement, I have a question for anyone or everyone.
It hasn't Jim.
Rather than have that thread taken even further off topic, I've split those few posts off to start a new thread here.
To answer your question, I'll start by saying there's a lot of misinformation posted on the Internet. Sorry I meant cr@p. It really depends on the context in which you're asking. If you're talking in general terms about storing any old cheap non-jewelled quartz watch for an extended period of time (say more than 5 years), then you'd be best advised to remove the battery altogether, to prevent any leakage of fluids from destroying the movement.
However, if we're being specific to Seiko 7Axx 15J chronographs (the original topic of conversation), then your quoted: “better” to “pull out the crown fully and disengage the battery.” is definitely the worst thing you could consider doing.
You may have seen me refer to 'Old Sticky Oil Syndrome' elsewhere on the forum. It frequently afflicts watches which have been stored for extended periods, often long after the battery has expired, sometimes even NOS (New Old Stock). When they were manufactured 35 years ago, each of the jewels (and metal bushes) in their movements were given a tiny drop of lubricating oil to reduce frictional losses. Over time, this oil picks up dirt from wear and gradually thickens (increases in viscosity) and eventually starts to add 'drag'. Worst case scenario, the pivots become clogged and act as a brake. When this happens, the electronics will continue to provide pulses to the stepper motors, but insufficient to overcome the drag, which is why, in such afflicted watches, you can sometimes see hands twitching, but not moving.
As you know, I maintain a large collection of 7A38's. I try my best to keep them all running, to ensure that the old oil in the jewels keeps circulating, preventing them from succumbing to 'OSOS'. This means I'm effectively on a never-ending cycle of battery replacements. That said, a #394 battery in a 7A38 which doesn't get worn much, can last over 5 years.
I should add that although I don't use their chronograph functions, whenever I open up one of my collection boxes, I'll use the inbuilt self-test to rotate their chronograph hands a couple of times, to stop them gumming up. Taking this to the extreme, I distinctly remember an erstwhile 7Axx collector posting on SCWF, that he left the chronograph functions running constantly, to prevent 'OSOS'. I took me a while to find
his post again, because it was in a thread about 6139's.
- 7A-Chrono-Running-SCWF-thetigeruk-Post.png (37.25 KiB) Viewed 5774 times
Must have done wonders for battery life (not) and gear train wear - and of course we all know that the 1/10s sub-dial hand comes to rest after 10 minutes (as a battery saving device), which partly defeats his object. What a klutz.