Hello and welcome to the forum, its always good to see another Scottish LED enthusiast there are a couple of members from Scotland here
I’am sure they’ll be along to say hello too.
As for your battery question I’ll have to leave that one to a more knowledgeable member I’am afraid, and for repairs etc I can
help with things like quartz crystal replacements but anything more involved I’ll leave to others, basically I don’t want to destroy
someone’s module, I know I wouldn’t like it.
Interesting you mention “you know what I mean-the ones that are advertised as: "Just needing a battery, but I ain't had the time to fit”
to me this reads “I’ve tried new batteries and its dead” still you never know what you’ll get until it arrives.
Good luck with your LED watch quest and please post a few pictures of your watches for us all to see...