I hope someone can help as this has happened a few times to me - I’ve got a Garmin Instinct Solar surf, in the day the battery said it has 17 days left, went to bed (I have the watch set so it stops tracking after 9pm & starts at 5.30am) and it said I had like 40 days.
Woke this am and the battery has gone and watch is off.
Any help would be much appreciated as I’ve asked Garmin a few times and not got much help.