From the quartz watches I have acquired over the years the majority of them use silver oxide batteries (with SR- prefix), as opposed to the alkaline batteries (with LR- prefix).

And very few of them, despite having been depleted for years, actually leaked. They usually leave a layer of copper salt on the negative terminal and after a simple clean the watch would've worked good as new.

I thought battery type doesn't really matter as long as they fit. Whether it's the more expensive silver oxide or the cheap alkaline battery, as long as they fit and they work, I don't have to worry about them leaking. And even if they did, it'd have been an easy job to clean up.

Until one day I open up one of my Elnix…

I thought the negative terminal was charred due to short circuit but when I used rodico to clean it, to my horror all 5 of the petals fell out.

On the negative terminal of the LR43 alkaline battery, the same dark color can be observed and it was obviously wet due to leakage of the highly corrosive potassium hydroxide electrolyte inside. This electrolyte has corroded the brass battery strip so much it structurally weakened the strip.

I opened up all 11 other watches that use the same batch of LR43 battery, all but 2 of the recently changed ones had some level of leakage. One other Elnix lost all 5 petals on its battery connection strip. They all did still run, with small amount of leaked electrolyte slowly eating away the brass on the battery connection strip.

Looking at the remaining unopened LR43 I realized they have all expired this month. Dang they are accurate. The unused ones actually were leaking, too!

Then I looked at the 7 other watches I have with LR44, exp. 2028. Well, they are leaking a tiny bit too.

See how a 3703 battery connection strip is also showing significant corrosion due to a leaky LR44. The plate seems thick enough to not disintegrate like on the Elnix though.

So it appears it's not really about the expiry date, but the type of battery. At least I haven't seen silver oxide batteries leak that badly.

See how badly an electrolyte leak can damage a watch. Look at the root of the battery connection strip corroded away, whereas the copper salt formed on top of the petals may have protected it from further damage.

With my bad soldering technique I was able to put a blob of solder to reinforce the battery connection strip, and even though the leak appeared severe, after cleaning and servicing the movement the watch has been working fine since.

As for the Elnix SG which has lost all 5 petals at first, I was able to bend up slightly the battery connection strip to maintain contact with the battery. Dropping in a replacement SR43SW (silver oxide) ensured the movement runs as smoothly as usual.