Up front; sorry for the length! I just want to give enough details so any of my misunderstandings may be addressed. I'm also more of a mechanical fan, so please forgive any nonsense I spew.
I have a Bulova Wilton precisionist chronograph I picked up three-and-a-half years ago; which I understand to be the average/expected battery life for that series. I don't wear it too often as it's usually one of my travel watches, and only occasionally worn for a couple days at a time otherwise. I mention this because I know Bulova states their ±10 SPY claim is only an approximate average, and that it will vary more and less than that throughout the year due to differences in temperature variations, etc and "balances out". That being said, even though it was only worn occasionally I was a lucky one and got one that was fairly close, if not actually within, said spec.
About a year and a half ago I read that battery life could possibly be significantly extended for these models by initiating but not engaging the chrono mode when not wearing and storing it. The rationale being that the power hungry 16bps seconds hand not continually moving would greatly reduce consumption. Seemed logical to me, so I've been doing it since; and whenever I went to wear after weeks or months of storing, after disengaging the chrono I noticed no obvious changes in accuracy. So I assumed everything was good.
A few months ago I grabbed my chrono before a trip and noticed the time was considerably off. I'm not a SPY junky being nitpicky - I mean minutes of difference from last use that wouldn't be expected of a standard quartz. So much so I simply assumed that last time I wore it I must've set the time wrong and didn't think about it again. Last week I grabbed the chrono after not wearing it for a while and again it's off by minutes. So in my head I make a mental note to pick up a new battery because I recall reading for these models a loss in accuracy means the battery is dying. No biggie.
After swapping the battery I was curious how low the old one was and wanting to know at what voltage the Precisionist starts to fall off. I grab my Fluke and the old 3V battery reads... 2.857 volts, which to me means... not a bad battery?
I get the chrono storage extending life was merely an assumption and the battery is near end-of-life otherwise. I'm also assuming from what I read 2.8v is fine for a 3v battery, but are Precisionists highly finicky on small voltage changes? What am I misunderstanding or overlooking?