This is why I think the KR8 Batts should be stamped with the month and date of manufacture, like the cartos are.. All batts should be.
I've had the same problem with a stainless... I noticed it was kind of scratched up compared to my new healthcabin stainless batts. I'm not sure if it was used, or old stock that it was scratched up, but the cartos from the same order were stamped almost a year ago! It won't hold a charge long at all, and it's supposed to be new.
Heavens gifts and healthcabin seem to have very new stock, I ordered cartos from both this month and they are stamped 11-2009, so that's where I'll go from now on..