milkyspit
Flashlight Enthusiast
Ever since reading one of Beretta1526's posts in which he mentioned a loss of intensity (measured by light meter) when he hadn't glued one of his emitters to the heatsink well enough, I've been tossing that bit of information around in my mind. Later Doug S confirmed that this is indeed a consequence of heat buildup in the emitter.
Based on that raw information, I propose a very simple test to determine if a given emitter has been heatsinked well enough.
Using a light meter, aim the light at the sensor and turn it on as would be done when taking a standard lux measurement. Don't use the "peak" setting on your light meter, but instead allow the readings to fluctuate freely. Try to find the most intense portion of the beam, then keep the light as still as possible.
Now wait, allowing heat buildup and eventual stabilization (hopefully) in the heatsinking system. Compare the intensity reading you got when first turning on the light with the later reading after thermal transfer has stabilized. The greater the drop from first to second reading, the less adequate the heatsinking system is.
I'm not sure if it's reasonable to expect no decline whatsoever, but that would certainly be the goal. Tentatively speaking, I'd be concerned if there were a big drop, such as 10% or more, between the two readings.
As one example, a recent light I built out of a Brinkmann 2AA body and BB750 LuxIII sandwich showed initial intensity of 974 lux, but after a few minutes of runtime, when the body of the light had gotten noticeably warm, the intensity had fallen to 830 lux. It didn't seem to fall any further from there. I interpreted the results as indicating that my heatsinking was inadequate.
This to me seems like a great and simple way to test the thermal adequacy of your mod in an objective manner.
Based on that raw information, I propose a very simple test to determine if a given emitter has been heatsinked well enough.
Using a light meter, aim the light at the sensor and turn it on as would be done when taking a standard lux measurement. Don't use the "peak" setting on your light meter, but instead allow the readings to fluctuate freely. Try to find the most intense portion of the beam, then keep the light as still as possible.
Now wait, allowing heat buildup and eventual stabilization (hopefully) in the heatsinking system. Compare the intensity reading you got when first turning on the light with the later reading after thermal transfer has stabilized. The greater the drop from first to second reading, the less adequate the heatsinking system is.
I'm not sure if it's reasonable to expect no decline whatsoever, but that would certainly be the goal. Tentatively speaking, I'd be concerned if there were a big drop, such as 10% or more, between the two readings.
As one example, a recent light I built out of a Brinkmann 2AA body and BB750 LuxIII sandwich showed initial intensity of 974 lux, but after a few minutes of runtime, when the body of the light had gotten noticeably warm, the intensity had fallen to 830 lux. It didn't seem to fall any further from there. I interpreted the results as indicating that my heatsinking was inadequate.
This to me seems like a great and simple way to test the thermal adequacy of your mod in an objective manner.