I was looking at the Garmin "How Long Will My Garmin Smartwatch Battery Last?" page, and I thought it was interesting that they list the "Up to This Much Battery Life in Smartwatch Mode" with Always On displays off, and then in parentheses the much smaller number (usually about a 1/3 of the top line number) with the Always On display on.
Apple's top line number (36 hours) assumes that: All-day battery life is based on the following use: 180 time checks, 180 notifications, 90 minutes of app use, and a 60-minute workout with music playback from Apple Watch via Bluetooth, over the course of 36 hours; Apple Watch Ultra (GPS + Cellular) usage includes a total of 8 hours of LTE connection and 28 hours of connection to iPhone via Bluetooth over the course of 36 hours. Testing conducted by Apple in August 2022 using preproduction Apple Watch Ultra (GPS + Cellular) paired with an iPhone; all devices tested with prerelease software. Battery life varies by use, configuration, cellular network, signal strength, and many other factors; actual results will vary.
Garmin's top line number (14 days) for the Forerunner 945 LTE makes the following assumptions: 90 Notifications per Day, 160 interactions, 2 device generated alerts, 1 hour outside bluetooth range, default display brightness and timeout, default face, gestures disabled, pulse ox disabled, no music streaming, no LTE usage.
In other words, to get to 14 days, one is never far from one's phone, never uses LTE, receives very few notifications, does not really use any other apps and has all the gestures and pulse ox turned off.
Apple's top line number (36 hours) assumes that: All-day battery life is based on the following use: 180 time checks, 180 notifications, 90 minutes of app use, and a 60-minute workout with music playback from Apple Watch via Bluetooth, over the course of 36 hours; Apple Watch Ultra (GPS + Cellular) usage includes a total of 8 hours of LTE connection and 28 hours of connection to iPhone via Bluetooth over the course of 36 hours. Testing conducted by Apple in August 2022 using preproduction Apple Watch Ultra (GPS + Cellular) paired with an iPhone; all devices tested with prerelease software. Battery life varies by use, configuration, cellular network, signal strength, and many other factors; actual results will vary.
Garmin's top line number (14 days) for the Forerunner 945 LTE makes the following assumptions: 90 Notifications per Day, 160 interactions, 2 device generated alerts, 1 hour outside bluetooth range, default display brightness and timeout, default face, gestures disabled, pulse ox disabled, no music streaming, no LTE usage.
In other words, to get to 14 days, one is never far from one's phone, never uses LTE, receives very few notifications, does not really use any other apps and has all the gestures and pulse ox turned off.