the degenerating condition of the power source in an electronic timepiece , that is , a diminished battery voltage , is indicated to the user by unusual performance of the watch bands . short periods of accelerated or decelerated hand movements alert the user to the battery condition . persistent though intermittent unusual hand behavior distinguishes the battery life signals from malfunctions or poor timekeeping . a voltage detector circuit monitors the power source and on low voltage initiates the warning signals which are derived from the divider network of the timepiece . mechanically resetting the hands to remove the visible effects or erratic hand movement , serves to reset the battery life detector circuits and repeat the warnings .