in a digital electronic timepiece , at least one of the digital displays changes color to indicate that the battery is nearing exhaustion . the display is made up of two sets of display elements , for example leds , disposed closely adjacent alongside one another . the two sets are of different display color , eg . red and green . circuitry responsive to battery voltage causes display elements of one set to be illuminated when the battery voltage is normal and causes display elements of the other set to be illuminated when the battery voltage drops below a predetermined value . the resulting change in color of the display indicates that the battery is approaching the end of its life .