The Fenix 8 51mm AMOLED is rated for up to 29 days in smartwatch mode. The 51mm Solar version reaches up to 48 days with three hours daily in 50,000-lux conditions, or up to 149 hours in GPS-only mode with 50,000-lux exposure during use. If yours is barely making it through a weekend, check which settings and activities are using the most power.
The display can be a major factor in battery use. The AMOLED option on the Fenix 8 is gorgeous, but keeping its screen visible uses more power. Display settings, automatic sensor readings and GPS settings during activities can all affect battery life. Walk through these changes and check how your runtime improves.
Turn Off Always-On Display
Always On Display affects battery life on the Fenix 8 AMOLED. The watch looks great with the screen always visible, but it pays for that look in battery life. This setting applies to AMOLED and MicroLED models, rather than the Solar models.
From the watch face, hold the menu button and select Watch Settings > Display & Brightness > Always On Display and turn it off. You can use Wake On Gesture to turn on the screen when you raise and turn your wrist to check the time.
Drop the Screen Brightness
Screen brightness is another setting to check when the battery drains quickly. You don't need it that bright indoors. Lowering the brightness can help extend battery life, so choose a level that still lets you read the screen comfortably.
From the watch face, hold the menu button and select Watch Settings > Display & Brightness > Brightness. Reduce the level, then check that the screen is comfortable to read. You can also shorten Timeout so the screen turns off sooner.
Switch Pulse Ox to On-Demand Mode
Pulse Ox measures blood oxygen saturation, and using All Day mode decreases battery life. If you don't need automatic measurements during the day or while sleeping, switch to manual readings. The readings can help you track how your body is acclimating to higher altitudes.
Go to Watch Settings > Health & Wellness > Pulse Oximeter and switch it from All Day or During Sleep to On Demand. You can still take a reading manually through the pulse oximeter glance while sitting or inactive, but automatic measurements will be turned off.
Disable Voice Controls
The Fenix 8 added voice commands and the ability to answer calls. Wake words let you activate voice features without a button press. If you don't use that convenience regularly, turning off wake words for your watch and phone's voice assistant can help extend battery life.
Go to Watch Settings > Power Manager > Battery Saver > Edit and select Wake Word to disable the wake word for voice commands when Battery Saver is active. The watch shows the hours of battery life gained with each setting change, so you can see the estimated benefit.
Force Restart the Watch
Sometimes a background process gets stuck. A Connect IQ app might loop, a sync might hang, or the system itself might just be in a bad state. A simple restart may help with a temporary software problem.
Hold the power button down until the watch turns off, then turn it back on. Check your battery percentage over the next few hours. If drain returns to normal, a temporary software problem may have been the cause.
Check Battery Usage on the Watch
The watch's Battery glance shows estimated battery life and recent battery usage, including a breakdown by activity and feature. Check it to see what has been using power before changing settings. It can help you decide which features to adjust first.
Open the glances list on your watch and select Battery. If it isn't visible, add it to the glances list. Review recent use by activity and feature, then adjust the settings that matter most for your routine. A watch face that doesn't update every second can also help extend battery life.
Turn Off Move IQ
Move IQ is Garmin's auto-activity detection. It can recognize activities such as walking, running, or cycling. If you don't use automatic activity detection, try turning it off and compare battery use with your usual routine. You can still start workouts manually when you want to record an activity.
From the watch face, hold the middle-left button, then select Watch Settings > Health & Wellness > Move IQ and turn it off. You'll still be able to start manual workouts without issue.
Update the Firmware
Firmware updates can include fixes and improvements, so it's worth checking whether your watch has an update available. If battery drain began recently, updating is one troubleshooting step to try before a reset. Check battery use afterward with your usual settings and activities.
Sync with Garmin Connect to receive updates automatically. To check manually on the watch, use Watch Settings > System > Software Update. Garmin Express is another supported option.
The Watch Face Could Be the Leak
Third-party Connect IQ watch faces are a mixed bag. They look great, but some of them redraw the screen constantly or poll for weather data every few minutes. In my experience, a poorly written watch face is the most common hidden cause of rapid battery drain.
Switch back to a stock Garmin watch face for 24 hours. If your battery life suddenly improves, you've found the culprit. Stick to faces from trusted developers, or just use the ones that come preloaded on the watch.
Enable Battery Saver Mode
Battery Saver lets you quickly adjust settings to extend battery life in watch mode. You can choose a low-power watch face, disconnect your phone and Wi-Fi, reduce screen brightness, or turn off sensors such as wrist heart rate and the pulse oximeter. Which features remain available depends on your choices.
Turn on Battery Saver from the controls menu, or go to Watch Settings > Power Manager > Battery Saver and select Status. Select Edit to choose which settings change. The watch displays the estimated hours of battery life gained with each change, so you can balance runtime with the features you need.
Factory Reset
If the watch still drains after every fix above, a factory reset may help with a persistent software or configuration problem. This is a last resort because it can erase your data and settings. Sync the watch before proceeding so you can preserve your recorded activities.
Hold the middle-left button, then select Watch Settings > System > Restore & Reset > Reset. For a full wipe, select Delete Data and Reset Settings; Reset Default Settings preserves user information and activity history. Set it up from scratch and re-pair through Garmin Connect, then monitor the battery for 24 hours without installing any third-party apps or watch faces. If drain is still abnormal after the reset, further troubleshooting may be needed.