The Bionic Ring sends a notification, if battery is low.

The SmartHealth app displays a notification if the battery of the Bionic Ring is below 20%.
To receive this notification, the user must have allowed notifications in their general phone settings for the SmartHealth app.

To change notification settings on iOS see: https://support.apple.com/en-hk/guide/iphone/iph7c3d96bab/ios

To change notification settings on Android see: https://support.google.com/android/answer/9079661?hl=en