Battery life varies depending on use and other factors.
In tests, for example, Apple achieved 18 hours of battery life with the following usage: 90 time checks, 90 notifications, 45 minutes of app use and a 30-minute workout with music playback from Apple Watch via Bluetooth. Other examples of battery life under different usage are available here (including up to 6.5 hours when using only the Workout app):
http://www.apple.com/watch/battery.html
If your watch is experiencing shorter battery life than Apple's examples suggest you should expect try the following steps, which have helped to resolve battery life issues for some users:
- If you have not yet done so, update your iPhone and Apple Watch to the latest software:
- Close all open apps on your iPhone and then restart both devices:
- On your iPhone: double-press the Home button, then swipe up on each of the app previews to close them.
- Turn both devices off together, then restart your iPhone first.
- Restart your Apple Watch - Apple Support
- Unpair and re-pair your watch:
- If you have ever previously used the Workout app and/or any third-party fitness tracking apps (such as Strava) to record workouts on your watch, check on your watch to see whether there is presently a paused activity within any of those apps. If there is, end that activity from within that app on your watch (not on your iPhone).
- Under earlier software versions, some users reported experiencing battery life issues in connection with using corporate profiles and/or Exchange Calendars. If you are using an Exchange Calendar, one or more of these steps may help:
- Archive your Exchange Calendar for all items before today.
- Remove / delete all old inbox messages relating to calendar invites (accept and decline notifications).
- Create a rule in your Outlook Mail account that moves all future accept and decline replies, immediately upon receipt, into a separate mail folder that does not sync with your iPhone and Apple Watch.
- Check your Exchange Calendar for errors.
- Finally, it may help to remove all third-party apps from your watch and then monitor battery performance after adding them back, one at a time. The same applies in respect of watch face complications.
Having tried the previous steps, if your watch continues to experience significantly shorter battery life than Apple's examples suggest you should expect, contact Apple Support (mail-in service may be available) or make a Genius Bar reservation with a view to having your watch checked, if recommended by Apple (under warranty, if eligible):
To check your warranty status (the serial number is on the back of your watch):
More information:
http://www.apple.com/watch/battery.html