Typically, the lithium battery in G-Shock watches has a lifespan of two to six years, depending on the usage of alarm and backlight features. If you notice signs of a low battery, such as a fading display, dimming numbers on the LCD display even with the backlight on, or a constant low battery sign on G-Shock models equipped with a battery level indicator, it is recommended to visit the Casio service center for a battery replacement.