Website for Nathan Moore, Physics, Winona State University
After maybe 3 - 5 years of use the battery would only hold a charge for ~20 minutes of recording a bike ride.
Sent back to Garmin for a new battery (replacement/refurbished unit). Replacement was about $60, shipping took a week. Needed the serial number on the back of the watch.
I probably could have bought a new battery for the watch for less than $60, but I wasn’t confident I’d be able to seal the casing properly. Replacement unit works great.