I'm guessing 15 minutes was probably enough time for the heat to transfer even without wrapping. There probably was a lot of emitter cooking during that time though.
If the heat was only transferring from the emitter pill to the outside through an air gap, then it would never get too hot to hold. For an unwrapped p60 to make the outside of the light too hot to hold, that is really hot, there would have to be a solid thermal pathway. I think that a nice solid piece of aluminum that is connected directly to the emitter/driver pill and the exterior of the light would do perfectly. That piece of aluminum is in place, the aluminum reflector.
Well, that's how it happened. And, when I wrapped it like I normally do, it didn't do it any more. I'll try it again to make sure I didn't remember wrong but I'm sure I did not.
Okay, right now I am turning on one of my L2Ps on high with a wrapped Ultra Fire XM-L drop-in. With my new DMM I tested the amps at 2.90 - 3.15. ($40 DMM so, if that's accurate) Gonna see if it gets as hot as it did on Sunday.
Foy
Okay. Looks like I put a half dead battery in there. Starting to go dim now, about 30 minutes later. Got hot but nothing like the other time. Gonna try it now with a fresh battey and no wrap.
Foy
16 minutes later and it is nearly too hot to hold so, it is what it is. The only difference is this L2P is grey. (and, no wrap of course)
Foy
that makes sense Foy. With the wrap, the heat is dissipated along the entire length of the head. More spread out. Without the wrap, the heat travels through the aluminum reflector to a more concentrated area near the bezel. If the amount of energy dissipated is roughly the same, it would make sense that if the energy is dissipated over a larger area it would not be as extreme to the touch as it would if that energy were more concentrated.
Now that you mention it, it is hotter around the head on the unwrapped light.
Foy