watchOS 9 introduces a new Low Power Mode for the Apple Watch Series 4 and later that is designed to extend battery life by disabling or limiting some features and sensors while enabled, such as the always-on display and background heart rate monitoring.
In a new support document published today, Apple detailed specific features that are disabled or affected when Low Power Mode is turned on:
Low Power Mode turns off these features
– Always On display
– Heart rate notifications for irregular rhythm, high heart rate, and low heart rate
– Background heart rate measurements
– Background blood oxygen measurements
– Start workout reminder
Low Power Mode turns off these features when your iPhone isn’t nearby
– Wi-Fi and cellular connections
– Incoming phone calls and notifications
Low Power Mode affects these features
– Making a phone call can take longer
– Background app refresh happens less frequently
– Complications update less frequently
– Siri can take longer to process a request
– Some animations and scrolling might appear less smooth
For safety purposes, Apple says Fall Detection continues to work in Low Power Mode.
To enable Low Power Mode, swipe up on the watch face to open Control Center, tap on the battery percentage button, and turn on Low Power Mode.
When an Apple Watch’s battery percentage drops to 10%, a Low Power Mode alert asks users if they want to turn on the feature. Low Power Mode turns off automatically when an Apple Watch is charged to 80%, unless users manually turn it on for a set number of days.
Apple says users can have Low Power Mode turn on automatically when they begin a workout, with metrics such as heart rate and pace still measured.
Apple notes that when Low Power Mode is enabled without your iPhone nearby, and you open an app that requires a data connection, Wi-Fi or cellular connectivity will resume so that the app can function properly, which can cause “significant battery consumption.”
watchOS 9 was released today as a free software update for the Apple Watch Series 4 and later. The new Low Power Mode is separate from the Apple Watch’s existing Power Reserve mode that only displays the clock when enabled.