3) Replace when you allready have it open for belt replacing etc.

Battery life may also depend on how the unit has been used.  My mother-in-law and I both have BC9500s of similar age.  She used to turn hers off at the wall power switch every night, and her battery failed about 10 years ago.  Mine is still going strong (or at least it was when I put it in a box about 2 years ago!).  So I guess the battery has to work a bit harder if it is compensating for lack of mains power more frequently, or for longer periods overall.

But I agree with madskp - something else is likely to fail before the battery so just replace while it is dismantled.  Plus the BC2300 and similar models are far easier to replace then BC9500.

I plan to replace batteries in my BC9500 and second BC2300 in the coming weeks when I give them a quick clean and service. I was also going to do the same for my two BeoSound 1s, but they are working well in daily use so I am hesitant to start poking around inside - not even sure where the battery is!

2) could also be replace in any case to prevent battery leakage.

But as Guy notes the batteri condition can vary much dependent on the use of the product

A good example of why preventive battery (super capacitor in this case) replement is a good idea

Hello fellow B&O lovers, Just a quick question about CR battery replacement. Is there a setup procedure that is needed after you replace the battery? I replaced one in an older Beosound Ouverture the other day and now it has issues receiving some commands from a Beo4 remote. I hope you can help. Thanks again.

I can't see any specific procedure in the service manual, however perhaps give it a bit of time on mains power then unplug, reconnect and try again.  When I replaced the battery on a BC2300 I have to reset the FM offset, but such a discrepancy wouldn't effect the IR/remote response.

If you have the service manual, you could run through some of the Test Mode procedures to see if there are any faults - it's possible that the main processor may be corrupted.  Either than, or disconnect/reconnect the battery to see if that clears the fault.