mcbit This is what I did with my Edge 130 for extremely cold and long winter rides: https://forums.garmin.com/sports-fitness/sports-fitness/f/edge-130/253899/external-battery-pack-for-edge-130-end-of-battery…
Helpful information for all:
Leave the device switched on (!!) and charge slowly. The battery seems to have returned to normal.
Not "officially", but people have done it. Before you go to that extreme, try running it all the way down to no battery left at all, then fully recharge. Sometimes the battery algorithm needs a reset. For best battery life it's best to never fully charge or discharge. I stop charging mine at around 88% and rarely use it past 50% battery. If you've done too many deep discharges it may be compromised.
I have the same issue. When my 830 is connected to an powermeter and heart rate strap + using navigation my battery is empty after less than 6 hours. Thats a real problem when you do longer rides or use it for a bikepacking trip.
The 1030 devices of my friends still have more than 50% battery life after the same time using the same sensors and navigation.
My forerunner 965 works for days using it for running, heart rate monitoring always on and listening to music.
Actually I think the battery is not good anymore. Unfortunately I couldn't find a service to replace the battery.
mcbit This is what I did with my Edge 130 for extremely cold and long winter rides: https://forums.garmin.com/sports-fitness/sports-fitness/f/edge-130/253899/external-battery-pack-for-edge-130-end-of-battery-angst