Hey BLFers… had a great time last night watching July 4th fireworks with wife + kids. Took along my newest hands-free light an Energizer night strike anglehead and it handled the night just fine. I was worried about it over-heating, or thermal dimming being a plastic light with only a small heatsink inside, but it ran completely stable and cool for the 35 minute walk back home.
Something thats always puzzled me about these lights is their dramatic variation in thermal performance. Form left to right: Energizer night strike XRE-EZ900, 110 Lumens OTF, 2AA in parallel Surefire E2L XRE-EZ1000, 110 Lumens OTF, 2CR123 Fenix L1T XRE-EZ1000, 90 Lumens OTF, 1AA Fenix MC-10 XPE, 115 Lumens OTF, 1AA
All these lights are about the same Lumen OTF, similarly BIN’d emitters… Why do the Fenix lights run so much hotter/warmer to the touch than the Energizer and Surefire? The first two run ICE cold for the entire duration of battery charge, while the latter two get very warm after 6-7 minutes.
I don’t want to get into a Fenix VS Surefire drama (save that for the other forum). What I am trying to understand is why is there so much more heat generation in the latter 2 lights, when they are all emitting the same lumen output?
I’d say the Fenix lights just have better thermal transfer (apparently). The heat being initially generated should be the same and Fenix just manages to get that heat transferred more efficiently.
yeah i’d saw hotter=better heat sinking or lighter aluminium…I know the roche F12 I have gets hot instantly…it is very light though and I think that is why…
Exactly gcbryan is right energy can never be created only transferred from one form to the other in this case chemical energy (the battery) is transferred to light and heat energy (the driver and emitter). So they all did the same thing and transferred the same amount of chemical energy to heat and light energy but some conducted it better to the body of the light while the others kept the heat energy inside the casing so you couldn’t feel it.
Thanks… yep you guys nailed it. I took the energizer apart and ran it for 3-4 minutes and the little aluminum heatsink got SCORCHING hot. Too hot for me to touch longer than a second or two. Theres a lot of heat, its just bured under the plastic shell.
Check how much air space there is inside the flashlight head and try filling that with thin metal shims (you can get thin copper at most garden/hardware stores, it’s used around planters to stop slugs, snails, and in door and window frames to block drafts). That should conduct the heat from where it’s produced to the shell.
I doubt that will do much good. Since the shell is plastic and will not conduct the heat from the copper to the air, about all you will accomplish is taking a few more seconds to heat the sink. All the mass you add won’t do anything but delay the time needed to get hot.
