Why does my watch battery drain on an outdoor walk activity when fully charged?

Hi Sarah_GMack,

The support article Use Low Power Mode on your Apple Watch offers information that may help with battery life during your workouts:

"Workouts in Low Power Mode

When you use the Workout app in Low Power Mode, your battery lasts longer while metrics such as heart rate and pace are still measured.

You can turn on Low Power Mode in Control Center or Settings, or you can have Low Power Mode turn on automatically:

1. Open the Settings app on your Apple Watch.
2. Scroll down, then tap Workout.
3. Tap Low Power Mode.

Now Low Power Mode will turn on automatically when you begin any workout in the Workout app."

and

"Preserve more battery life with reduced GPS and heart rate readings

When you do an outdoor walking, running, or hiking workout with the Workout app, you can have your Apple Watch take fewer GPS and heart rate readings. Reducing the frequency of these readings can extend your battery's use significantly during long workouts.

This feature is available with watchOS 9.1 and later on Apple Watch SE (2nd generation), Apple Watch Series 8, and Apple Watch Ultra.

1. Open the Settings app on your Apple Watch.
2. Scroll down, then tap Workout.
3. Tap Fewer GPS and Heart Rate Readings. 

Now the feature will turn on automatically when Low Power Mode is active and you begin an outdoor walking, running, or hiking workout in the Workout app. Your watch needs to be in Low Power Mode for this feature to work."

Regards.