Avoid Busy Watch Faces
It may not be evident at first glance, but the more colorful and animated your watch face is, the more battery life it will consume.
These usually aren’t a problem for the Always On Display, as nearly every watch face remains pretty static when your wrist is down. However, if you’re frequently checking the time or raising your wrist for other reasons, that watch face is springing into action each time.
Similarly, complications that engage the Apple Watch sensors can also take a toll on your battery, such as the heart rate and noise monitoring complications.
The most power-efficient watch faces are the ones that are mostly plain black backgrounds, like Simple and Numerals Duo.