Pretty sure the battery in mine has been there for at least 5 years, and
the scanner has been unplugged for almost 6 months now. I've had the 2004
since they first came out and think I've only gone through 2 or 3
batteries in that time. I also have a pair of 2005s and they are each on
their second battery.

That's pretty well my experience also. Sold the 2004 several years ago but
still have a 2006 that I purchased new and batteries seem to last in them
just about as long as they last on the shelf. RM~

PS, Thanks for reminding me, guess I'd better check the battery in my 06 and
make sure it hasn't started to corrode.