Question about Ei Electronics Ei650 smoke detector

The smoke detector does not flash permanently as a control indicator during normal operation. In normal operation, the LED is switched off so that the detector is suitable for use in bedrooms. The LED only flashes at certain intervals in certain states such as alarm, low battery or fault. For example, the LED flashes once in the event of a battery warning and quickly every 0.5 seconds in the event of an alarm. There is no regular, occasional flashing to check operation.