photoelectric detectors use infrared LEDs. and they are inside the detector, shielded so stray light will not cause any problems.
Any red LED you see on a smoke detector is for statuses, not detecting
Thank you for the correction, you’re right. I got it mixed up with the status LED that some/most(?) smoke detectors have that will periodically blink to show that it’s active.
Regardless, a smoke alarm blinking red is to be expected, and doesn’t mean that it needs to be tested. Most of them will make a loud ping to notify the user that it requires attention, as you can’t expect people to notice the blinking LED alone.
it would be nice if there were smoke detectors that didn’t have flashing lights during normal operation.
Well, the problem with that is that a completely dead smoke detector does also not blink