Normally the Smart Cap Light turns on and off and dims with the main light; however, under certain circumstances. it will emits light signal to communicate with you in a smart and friendly way:-> Main Light OFF - Charging signals: the Smart Cap will pulse to indicate that the battery is charging; it will stay on to indicate the reach of full charge, as long as the charging cable is attached;-> Main Light ON - Dimming signals: while dimming, the Smart Cap will blink once to indicate the reach of minimum dimming, twice for maximum;-> Main Light ON - Low battery signals: when battery is low the Smart Cap will start blinking for several minutes, until the automatic shutdown of the device. Please plug in the device to continue operating and/or charge the battery.