As of the Apple Watch Series 4 and newer, watchOS 9 will include a new Low Power Mode, according to a recent announcement from Apple. The Apple Watch can run for up to 36 hours on a single charge when the Low Power Mode is set.
Many essential capabilities, such as fall prevention and activity tracking, are still available when the Apple Watch is in Low Power Mode, but others, such as the always-on display and workout detection, are disabled to save power.
The Apple Watch’s Power Reserve mode, which when activated just shows the time, is distinct from the new Low Power Mode in watchOS 9.
The brand-new Apple Watch Series 8 and Apple Watch SE, which are now available for pre-order and will go on sale on September 16th, will come with a variety of new features, Low Power Mode being just one of them. The Apple Watch Series 8 also comes with a body temperature sensor targeted for women’s health as well as crash detection technology.
With regard to the brand-new, high-end Apple Watch Ultra, Apple announced a new battery optimization feature that will be made available later this year and will extend the device’s battery life by up to 60 hours. This feature appears to be distinct from the Low Power Mode.