After 2 months but the battery was empty, without that the light had shone too much. The light has a day only about 4 times shone. The sensor itself always needs a little continuous current: Since the LEDs need little power, is the clear conclusion. That is also quite clear: The electronics must constantly measure if something changes in the monitored angle in the infrared radiation range. So, the electronics must constantly measure something. For the power goes away, for less light.
Still 5 points, since it is obvious: Without electricity, this measurement is not. The light is still better than its competitors, which I had ordered in parallel.