a2 led Aviator flickering in low power

[chriscoobs]

Hello all, i have a surefire a2 led aviator with red secondary lights and when the battery is depleated and it goes to only the secondary lights the red flickers about 5 seconds after i fully depress the button.

It flashes like my 120p on strobe mode(weaker and red of course however) and makes it hard to use the light for general purpose.

I have tried surefire and streamlight 123's with the same effect. Is this normal or do i have an issue? thanks
CHRIS,