I like to think aluminum & copper metal flashlight acting like headsink for led emitter. High thermal conductivity of Aluminum ‘237 W/(m·K)’ & Copper ‘401 W/(m·K)’ allow it to distribute heat really fast compare to lower thermal conductivity materials such as cast iron ‘52 W/(m·K)’, titanium ‘21.9 W/(m·K)’, stainless steel ‘14.3 W/(m·K)’ & PVC Plastic ‘0.19 W/(m·K)’. It reason why both aluminum & Copper used in cookware base of pans, heatsink & heat pipe, etc.
It’s not normal. It’s only ‘normal’ in the small enthusiast segment.
Most non-enthusiast buyers get worried when a flashlight gets very hot.
Think of it like a car, just because it can drive at 200km/h doesn’t mean you should do that, but it can
yes the problem is like 60% or more of emitters is produced heat, rest is lumens…. if the emitter didnt produce any heat it would be wonders…. many think its a flaw when a light gets very hot quick but that is the price we have to pay sadly…
How hot is hot? Some Acebeam and Armytek lights get over 60°C, which is nuts to me.
That’s just it:
Hot to the point of burning skin is not normal.
Warm to the touch is normal.
If it gets hot QUICKLY, that’s actually better. It means the thermal path is good and it’s pulling heat away from the LED.
If they don’t understand it the first time you explain it, tell them to turn on a (incandescent) 100 watt light bulb, and then lick it after a few minutes.
At the very least, they won’t be able to verbally complain to you anymore.
…about sums it up.
Along the same lines, people want the hottest new light but they’re surprised when it turns out to be literal.
Yeh. They want controlled fusion in a lipstick-sized tube, then return it because “it gets too hot”.
FW3A step 4 draws 561 mA and generates 177 lm pluss heat. Turbo draws 12A. If the Leds were as effective as in step 4 the flashlight would generate 3800 lm, pluss propositional amount of heat as in step 4. For turbo you can then add 1000 lm extra light energy lost as heat energy.
How about:
“This flashlight has the same power as a household lightbulb. Please remember that it will get very hot at high power, just like the lightbulb. For your safety, we have designed this flashlight to reduce power after 3 minutes at high power.”
(You can write “on turbo” instead of “at high power” if you prefer.)
Don’t ask me how to make people actually read the warning, though 
No offense, but I don’t like the idea of giving Sofirn suggestions about more flashlights with timed stepdowns. A timed stepdown is the worst solution both for muggles and enthusiasts. Repetitive activation of turbo will still heat up the flashlight beyond its designated threshold unless a thermal controller is in place, too. But once you have a thermal controller (like „ATR“ called by Sofirn) in place you don’t need to have both timed and thermal stepdowns. That’s why I suggested to Barry to implement 3-4 user-selectable thermal thresholds for stepdown. Sofirn could sell their lights with a factory default of 45-50°C and put a big warning sign as well as some instructions into their manuals how to raise the threshold by hidden settings in the UI.
Say: “Powerful flashlights get hot easily at the highest level. This is normal.”
“LEDs don’t get hot.” is fake news 
I really like what Phlogiston wrote.
Anyway, here is what I wrote a friend on the same issue:
Turbo is per definition only for a short time useable.
Turbo means you can’t sustain this level of output forever.
Like a 50m sprint on full pace or nitroglycerin injection in a motor. If kept for longer you overheat or the motor dies.
In todays flashlight it is normally one level below high where you can use it constantly. With a normal 18650 light that is 500 to 1000 lumen, depending how it is built.
LEDs produce heat as a incandescent light bulb, but only on a lower rate, but they do.
How hot the light gets depends on the output (the brightness setting) and how good cooling is (mostly the surface area of the lamp)
I know lamps with 5 seconds turbo time and some with 15 minutes.
3 minutes are quite long to light something up.
If you want a high output for long time you must buy big lights, e.g. the size of an old D-cell MagLigte
Fair dues
I would prefer a light with ATR-style thermal regulation too, as long as I can choose the temperature, change back to a timed stepdown, or even turn ATR and stepdowns off altogether. There are people who actually like an abrupt stepdown as a useful reminder to think about what their light is doing.
My favourite lights have no stepdown or ATR whatsoever, because I know how to use them safely.
My text was just an example. Sofirn can certainly change that last sentence to something like:
“For your safety, we have designed this flashlight with Automatic Thermal Regulation (ATR). This will reduce power if the flashlight gets dangerously hot. See page 4 of the user manual for instructions on configuring ATR.”
That way, people who don’t read the warnings can’t learn how to endanger themselves. Poetic justice
Thank you, I appreciate that 
Hey, I had an idea. Tongue in cheek. How about:
“In case of survival emergency, we have designed your flashlight with the ability to fry eggs. Please avoid frying your hand by mistake.” 
For a small, lightweight light, an li-ion battery can put out enough juice to heat it beyond the mass/dissipation limits.
The only way to stop it is to make a bigger light, or with a bunch of fins, or a fan, or just don’t run it that bright.
I’d rather have it available, even for a half minute, as long as it can limit itself if it gets too hot.
Several years ago high power filament lamp bulbs were restricted by federal law in Russia. We still can purchase them, but now they are sold as “infrared heater”.
You can make spacial label for such customers and sell flashlights as super modern portable hand heater.