Your Suunto 9 has a battery power management system uses intelligent battery technology to help ensure you watch does not run out of power when you need it most.
Before you start recording an exercise (see Recording an exercise) you see an estimate of how much battery life you have left in the current battery mode.
There are three predefined battery modes; Performance (default), Endurance and Ultra. Changing between these modes will change the lifetime of the battery but also change the performance of the watch.
By default, Ultra mode turns off all HR tracking (both wrist and chest). To activate the HR tracking (in Ultra mode) go to Options under the start indicator.
In start display, tap Options » Battery mode to change battery modes and see how each mode affects the performance of the watch.
You can also quickly change the battery mode in the start display by pressing the upper button.
In addition to these three predefined battery modes, you can also create a custom battery mode with your own desired settings. The custom mode is specific for that sport mode, making it possible to create a custom battery mode for every sport mode.
If while exercising you start navigating or use navigation data like estimated time of arrival (ETA), the GPS goes to Best, regardless of the battery mode.
In addition to the battery modes, your watch uses smart reminders to help you ensure you have enough battery life for your next adventure. Some reminders are preemptive based on, for example, your activity history. You also get notified, for example, when the watch notices you are running low on battery while recording an activity. It will automatically suggest changing to a different battery mode.
Your watch will alert you once when the battery is at 20% and again at 10%.