I have a DS1302 RTC and am wondering how long the battery will last. The battery is a lithium 3V CR2025. I have left it unplugged for about 2 hours and plugged it back in and it still kept it's time. How long can I reasonably expect from this battery?
5 to 10 years is typical, as only a couple of microamps is drawn in use. It must be a lithium primary cell for this,
ie 3.0V coin cell.
Check the datasheet for the CR2025, shelf life is 10 years normally.