In early September, Apple rolled out watchOS 9 and gave all supporting Apple Watch models (Series 4 or later) a killer new feature: Low Power mode. When turned on, it can almost double the "all-day" battery life of any recent Apple Watch, taking it from roughly 18 hours to 36 hours.
Unlike the "Power Reserve" mode that has been on the Apple Watch for years, Low Power mode still keeps track of fitness metrics and your workouts; it simply turns off battery-killing features (depending on your Apple Watch model, of course) like always-on display, automatic workout and frequency of detections for heart rate, GPS and cellular connectivity.
The Apple Watch Ultra supports Low Power mode as well, but to date it was mainly focused on extending its battery life for endurance workouts. Without Low Power mode, the Apple Watch Ultra can last roughly 12-hours for a continuous workout, but with Low Power mode turned on it can extend that juice to about 15 or 16 hours — which should be enough for the wearer to finish an Ironman (all of which typically have cutoff at 17 hours).
Just this week, Apple has rolled out watchOS 9.1 and its the biggest improvement is a new setting that works with Low Power mode for the Apple Watch Ultra. The new setting is called "Fewer GPS and heart rate readings" and when turned on it enables low mode — which Apple is calling "Low Power Mode Workout with Fewer GPS and Heart Rate Readings" — the Apple Watch Ultra can stretch its normal 36-hour battery to roughly 60 hours...and that includes 15 hours of workout time. It's pretty incredible for an Apple Watch.
The main thing that this new Low Power Mode Workout does is it reduces the frequency at which the Apple Watch Ultra takes your heart rate and GPS; according to Apple, heart rate readings are reduced to once per minute and GPS readings will reduced from once every two minutes. Just like the normal low power mode, it turns off the same battery-killing features and limits how often your watch searches for cellular connectivity.
How to Enable the New Low Power Mode On the Apple Watch Ultra
In order to turn on "Low Power Mode Workout with Fewer GPS and Heart Rate Readings," your Apple Watch Ultra has to be running watchOS 9.1 (or later). You can update your Apple Watch Ultra via the Watch app on your iPhone or directly on the watch. Go to Settings > General > Software Update and install the latest update if one is available.
- Open Settings on your Apple Watch Ultra.
- Scroll down and select "Workout."
- Toggle on "Low Power Mode."
- Toggle on "Fewer GPS and heart rate readings."