[WinDnDusT]

Thanks for all your responses! (Don, did you know that your team was sitting behind mine at Championships during Einstein matches? We were thrilled because our team numbers are sequential)

Al and Don,
I think I see the errors in my understanding. I was assuming it would be easy to track the contribution made by age (sulfation) to the internal resistance. I now understand that due to the multiple contributing factors (temperature, state of charge, amount of surface charge) to internal resistance, this is difficult to do. So I probably won't use #3 for making decisions, but I am still curious to try it as an experiment (using a controlled process to measure internal resistance). I also see that #1 isn't really doable because I don't know the conditions during the manufacturer's test.

So I think I was a little optimistic about tracking internal resistance measurements over time with the Battery Beak.

For #2, I gather that the most important thing is to make sure that you don't use a battery that the Battery Beak measures as 'Bad'. I think I see from the comments here that an internal resistance measurement of 'Good' or 'Fair' from the Battery Beak isn't the same as a clean bill of health because this type of test cannot reveal reduced cell capacity.

Does this imply that a battery can have reduced capacity without having an increased/abnormal internal resistance?

(Btw, Al and Ether, thanks for your explanations of discovering reduced capacity via long term test)