A method and system for providing charging information to a user of wearable device by predicting when a health sensor is needed most during the course of the day and cross-referencing that information with a user's personal calendar in order to determine the optimal time to charge the wearable device. Battery life of the wearable device may be monitored. Information may be stored in memory regarding sensor data detected by one or more sensors and associated with a time. One or more time slots may be identified during which the sensor data was lacking. The identified time slots may be compared against a calendar of available time to identify matching time slots. A next matching time slot may be determined, and a notification may be displayed on a display screen of the wearable device to recommend that the user charge the wearable device at the determined next matching time slot.