FYI for anyone struggling with battery life on their 945.
My 945 battery was lasting 3 days with normal usage (OHR, no SPO2, no music, activity tracking, 60 minute workout per day, default watch face, no phone notifications, brightness 5% with no gesture). Overnight it would lose 12% to 15% and the battery widget showed it was consistently losing 1.4%+ per hour regardless of how I set it up or how many times I would restart it.
I used the Garmin Support "chat" feature to talk with an employee who told me that there is a known issue with the 945 battery. They sent me an email with several steps to try to improve battery life (deleting certain files, hard resets, factory resets). None of these suggestions seemed to help so they started a return material authorization case (RMA). The nice thing here is that they sent the replacement 945 prior to shipping them my current one. No lost days! They also had me pull the .garmin file off the watch and email it in so their engineers could try to figure out what it happening.
New watch arrived yesterday - I charged to 100% and set it up with the exact same setup I was running before. I'm currently at 95.6% after 16 hours of use and a 45 minute workout. Battery widget now shows the watch is losing .1% to .25% per hour rather than the 1.4%+ mentioned above.
My point is if you think there's something wrong with your battery, you're probably right and it's worth letting Garmin know. Good luck!
