As an emerging wearable device, a number of commercial smartwatches have been released and widely used. While many people have concerns about the battery life of a smartwatch, there is no systematic study for the main usage of a smartwatch, its battery life, or battery discharging and recharging patterns of real smartwatch users. Accordingly, we know little about the current practices for battery use and management of smartwatches. To address this, we conduct an online survey to examine usage behaviors of 59 smartwatch users and an in-depth analysis on the battery usage data from 17 Android Wear smartwatch users. We investigate the unique characteristics of smartwatches' battery usage, users' satisfaction and concerns, and recharging patterns through an online survey and data analysis on battery usage.