aahhhh..okay got it. The light is not "cutting off" it is stepping down. Hmmm....I have done the following experiment with 3 of my 5 TN4A's-using freshly charged and recently purchased Pro's I take a TN4A out on my back deck at night, stand the light on its tail, click it up to turbo then stand a few feet away while watching the timer on my watch waiting for the light to clearly visually step down. None of the 3 TN4A's I tried this with ever visibly stepped down. I stopped the tests at the 45 minute mark for all 3 I tested. The cells still had enough voltage left to keep the LED indicator blue. NONE of them got "hot" either. Pretty warm yes but "hot" no.