At home, the multimeter showed 3.065v for that one's original battery, and 3.05V for the white bike's once-replaced battery.
I can't remember when I changed the batteries last. My internet searching indicates that I failed to post about it. In theory, I should get 1.4 years or 500 hours. The best I can tell, I'm getting 400 miles or so.
I replaced them both with fresh, 3.30v CR2032 cells. Unfortunately, these were bulk batteries, and I actually threw several away as being faulty in storage.
I may also need to adjust the wheel magnet, so I can be spaced a little closer, but I'm using monster magnets which trip the sensor from 2" away.
I thought I might be leaving the magnets such that they intermittently trip the sensor when not in use, but maybe not. The HRM (heart rate monitor) sensor has been replaced, and is down to 3.01v. For good measure, I replaced it with a new 3.31v cell. I think I got 65 hours out of the last one, but it was in the 2.7 volt range when I was losing signal from it. Obviously, it's much closer to the cycle computer than the speed/cadence sensor.
Anyway, there's not an easy reminder system for battery replacements, so I'm going to set up a reminder to swap all of the batteries every 5 months.
That's a little too often, but it's much better than getting into a ride and having half of the track missing because it keeps auto-pausing.