[dba-Tech] Life expectancy of a cell phone battery

How long can one expect a battery to live? My phone is several years old
now, and I feel no compelling reason to move into the modern smart-phone
era. My phone has a browser and a camera and I almost never use them; it
has some games, too, which I have never played. For me it's just a phone,
and a calendar/clock. Hell, I don't even play music on it.

I digress. I've noticed lately that it seems to require charging more
frequently, and it's certainly not because it's constantly in active use.
Is this an indication that it's getting to be time for a new battery?

-- 
Arthur