The watch is second hand but I believe first registered beginning of 2022 somewhere in APAC so I would think the battery is still good but I could be wrong.
During running with only GPS on I often take a big hit on battery in the first hour (circa 8 to 10%) and then it will slowly level off over a.few hours to about 6% per hour.
Strange thing is when I conclude the activity the battery will slowly creep back up around 5 points or so.
It concerns me because if I'm doing an ultra I don't want extra battery in the bag that only seems to be accessed post work out.
Grateful for any ideas.