Colder temps and early darkness has led me to use my lights more regularly taking my dogs down to the river in the evening after work. Lately I’ve been using my Convoy C8 , S2+ and the Eagle eye x6. None of these lights are thermally regulated and I kinda like that. They make a good hand-warmer when it gets down in the single digits(Fahrenheit). So my question is; does it harm my lights to get fairly warm? Not burn my hands warm but toasty warm. I know the rules as far as battery concerns but will it shorten the life of the flashlight itself?
Yes LEDs get shortened life span at higher temperatures.
There is no way of knowing exactly how much without knowing the junction temp of the LED.
The most important thing is the heat path close to the LED
A DTP star can have a 80dC Tj at DD
While a XPL on a non DTP with hollow shelf one could be already cooking at 130-150dC while both hosts have the same temperature
Both lights will heat up almost the same as the power is the same
When it burns your hands, it’s time to bring it down a notch.
or use a glove :confounded:
When the LED unsolders itself , turns blue or stops working you know it was too hot
“Tighten until it cracks, then back off a half-turn.” :smiling_imp:
If you want to use flashlight as hand warmer, you need to reverse the question.
You want some (better if it will be stable) amount of energy transfering from the host to your hands. And you need to know how much energy is enough for your comfort. I would guess not more than 10W. Considering LED efficiency, 12-13W consumption. Or 4-5A from single cell.
As mentioned above, with good thermal path (quality pcb over solid alu/cu shelf) you will burn your hands before LED start degrate.
I measured some things about 18650 tube-style lights with a DTP-board and good heat path to the shell: I do not know led life over time (I guess it will be ok though) but they can be 90 degreesC for a longer period without anything going wrong, while 55 degrees is the pain limit.