A test flashlight was designed and made to compare runtimes with a similar light engine in more standard host. A NexGen 500 driver was coupled with a J flux bin LuxIII in the test light as well as in an aluminium A-19L-1x123-McE2S host. The exercise was to see if a light with an isolated and heated battery chamber would perform with a longer run time when subjected to ambient conditions in 100% humidity (submerged).
In the test light, the LED heat sink is an aluminum slug that sits with snap fit slug into a combined converter and battery sleeve made of brass. The heat sink is held captive by a brass cap nut that forces metal to metal contact between the heatsink and the brass sleeve. The fit is so tight that with any thermal expansion of the heat sink, the fit will become an interference fit and a good thermal path between the heatsink and brass sleeve will result. The converter is soldered down on an inner shoulder lip within the sleeve and any heat it generates will migrate to the brass sleeve as well.
The brass "core" has a snug fit within the Delrin head and remains captive in the head. The aluminium reflector does not contact the "core". The portion of the core which extends into the Delrin battery tube or body does not contact the walls of the tube but is surrounded by an air space approximately .030" thick. The electrical circuit is closed when the core is forced rearward to the point that a titanium contact cup makes contact with the rear lip of the brass sleeve. This titanium cup is isolated from the Delrin tube buy a couple O-rings which hopefully increase the thermal resistance from the core to the outer tube.
Below are the run times of both the A-19 "control" as well as this test light:
In the case of the test light, it was measured in air, submerged in water and then submerged in water with a neoprene "wetsuit" sleeve or bootie covering it. The tests done in water consist of lux readings but not at a measured 1 meter from source to meter. The lux readings are there only for relative measure within a single test and illustrate when the light drops out of regulation. The air tests were a measure of lux at one meter.
I believe this light as well as these tests show that there is merit to consideration of the thermal condition of the battery chamber and it is possible that excess heat from the LED could be used at advantage in heating the battery chamber. The ambient environment in which a light is used should be taken into consideration and not only ambient temperature but ambient humidity and how it effects the thermal state of the light and battery chamber should also be considered both in terms of design as well as selection of the light to be used.