Started around 74*F. I did a bunch of LPM runs. There is a narrow temp range that this laser seems to prefer. I wish this laser had a momentary button due to its power curve. It's output never levels out it's a roller coaster. I will do longer tests with half charged batteries this evening to see if it is the driver cutting current due to heat.That Spartan drops quite considerably. What temperature was the laser at and was it mode hopping?