I am using the ones from you. If this is as expected then fine. I think my test proves that the bupbat does get recharged, otherwise the time would be lost right away and not after two hours. I was under a misconception that an RTC backup battery should last for days, if not years. We used some RTC chips back in mid-1990's, can't remember the type number, that had the battery built in. So clearly not vety big. IIRC, the catalogue page claimed the battery should last 10 years.