I don't know what the "official" estimate is, but I just removed one from = my desk drawer that had been in there for at least six months, and the = batteries were right at 100%. Are you using rechargables by any chance? >>> albertgriffith@xxxxxxxxxxxxx Sunday, November 14, 2004 2:34:16 PM >>> Does anyone have any idea as to how long a B.P. can sit idle on a new set = of=20 batteries? I haven't used mine much lately and I keep having to replace = the=20 batteries about every month, even though I've only used it three or = four=20 hours each time.=20