This is totally different, this very expensive flashlight is lacking a basic safety feature that could potentially lead to serious injury of the user - this is entirely preventable. This is more akin to your Ferrari being equipped with an automatic transmission and simply not shifting into a higher gear or something simple and dumb like that - it just shouldn’t happen at all.
Granted, perhaps this is not normal and is a malfunction, but is still an issue that should not be present
The first thing they’ll say is — You’re suppose to hold a flashlight not Tail stand it on 10000 lumen mode —- I’ve played around with small lights like a S2+ with a fet /triple — tail standing at over 5 amps will produce some serious heat —- but will this kind of power there should be some kind of timer / thermal step down
If you watch YouTube videos of this light in action on turbo or any higher modes, the fan kicks on automatically when it hits a certain temp. The fan itself is entirely inadequate for dissipating 400 ish watts, so it’s mainly there to keep things from self destructing. There’s a malfunction in this MS18 perhaps, and yes, it could be bad.
its just too much lumens in a light to be any practical, whats the point light gets so hot it turns into a bomb ?
No, timer is a poor solution. If it was a $10 light I wouldn’t complain about timer…if it was a $20 light I would have mixed feelings. But it’s a $700 light. There shall be thermal control.
As said before, it’s been a standard in $50 lights for years. Actually in BLF lights for $30 as well.
There is no excuse to shipping such undeveloped UI in expensive light.
But it’s Imalent. Powerful but badly developed lights for a high price.
Sometimes we disable temp protection on purpose because when it’s on the flashlight doesn’t even reach 45°C but the immalent takes it to another whole new level 
It ran for 36 minutes before I turned it off, it sat on top of my integrathing sphere, so the heat only built up inside the sphere and couldn't get out anywhere. So, this may not be a practical problem for most people.
It happened when I starting the light in the 10.000 setting, so I didn't turn on the higher modes this time. I already finished runtime tests for the higher modes the days before.
And yes, that Heat warning symbol was flashling.
Thanks for your explanation and clarification on the procedure ChibiM. 
I charged my light and I may try it tonight for that period of time to see how it behaves. I will report then to let you know if this is a “standard” situation for all the lights, or if it may be a “defective” one you got concerning the thermal control.
BTW, to those unfamiliar with this flashlight and its thermal control, please read the point 6 of the user Manual (click for larger image).
Well, the Caution hot surface warning is there for a reason 
Yeah, those Imalents tend to get HOT!
I remember burning a hole in my table after doing a current measurement 
However this looks very extreme! And it lasts for quite a while, usually they step down quite fast.
Conclusion; you got an ultimate BLF enthusiast light over there, it’s very bright,
it does not step down, it lasts, its the ultimate hot-rod!
Imalent: “we put the hot in hotrod!”
So, I picked my MS18 today to check how it behaved in comparison with ChibiM’s one.
Honestly, I didn’t do a test that long , but I guess the conclusions can be retrieved from the table below.
Test was made at 10.000 lumens during 10 minutes only.
I stopped the test, as the head of the flashlight was already too hot to handle (if grabbed by the head), although handling it through the battery tube with thumb on the switch was still OK, but warm. By then the tube was at around 38.3ºC
At 10m I also felt some different smell, and while appraching the head to smell it, I accidentally touched the host with the nose tip and burned it 
Not nice! Blame is on me
I stopped the test because, given the heat progression, I knew this would lead to similar results to what ChibiM got.
| Voltage | ºC near the switch | ºC head (near bezel) | |
| start (OFF) | 16.38V | 22.4ºC | 22ºC |
| 1 minute | 15.74V | 25.3ºC | 26.9ºC |
| 5 minutes | 15.62V | 34.4ºC | 45.3ºC |
| 10 minutes | 15.56V | 42.8ºC | 65.5ºC |
If at 10 minutes the exterior is at this temperature, I will assume that the inside is above 70ºC , which means that the fan didn’t activate , as stated in the User Manual. Of course, without having a way to measure it internally, this is just a wild guess, but it seems logic to me that the heat will be higher in the internals.
This said, what I can say, again, is DO NOT LEAVE THIS FLASHLIGHT ON UNATTENDED, in any level, but specially at this one. If above it, the fan will turn ON. If below, I believe that the light will still get hot, but the amount of heat is probably lower.
Also, this test is of course much more “accurate” than the one I did yesterday in which the battery was more drained, while today it was starting freshly charged !!
Thanks ChibiM for alerting to this situation!
Dang reminds me of hot rivets and iron workers.
It’s more like complaining that your Ferrari engine overheated when you were driving 20mph because the radiator fan never came on. And their answer is “who the heck drives a Ferrari 20mph? We never anticipated that!”
I have noticed mine getting quite hot on 10k, never ran it more than about 15 minutes though. I’m guessing they’re all that way. Good to know. My imalent dt70 the temperature control doesn’t work on strobe mode either…
Interesting how the 4 brightest modes (22,000, 30,000, 60,000, and 100,000) worked fine, but the 10,000 lumen mode overheated.
But according to the manual, the fans only turn on in the 22,000 and higher modes. So it seems the fans are key for keeping this flashlight from overheating.
But according to the manual it should also activate when it reaches 70°C internally.
Or am I wrong in my interpretation of the point 6?
You are correct according to the manual, but it seems only the fans turning on keeps this flashlight from overheating.
Obviously the MS18 should overheat faster in modes greater than 10,000 lumens, but it appears the the fans in conjunction with the thermal protection prevents it from happening.
I don’t know nothing about flashlights, but when you turn on a flashlight upside down the heat that normaly would excape is trapped. since it is not a expected usecase, you can’t culprid the manufacture.
it’s more like driving a Ferrari in reverse gear up to 20.000rpm and complaining there was no protection against it
I understand your reasoning, but it's not correct. If a flashlight has is temperature controlled, they better make sure that temperature controller works each and every time. I hope they will fix this issue, because 10,000 lumens produce a lot of heat..
Honestly, these car comparisons are completely out of place. Running a flashlight on any mode (10000K / strobe) for extended amount of time is not comparable to any of these situations.
6.C the fans will not operate below 22000 lumens sounds like you get nothing below 22000 lumens even if its on fire.
I guess they were sure that the passive cooling was fine for below 22000 lumens in whatever testing they did. Perhaps not the same testing as here given the results.
But why disable it at all, if it’s at 70 degrees it’s at 70 degrees and that should be the major issue.