Agreed, I’m not sure how you’d compare lights though.
I can’t think of a solution other than just labelling max lumens at 20C ambient - the exact numbers are no good for those in particularly hot or cold environments but at least it’s a common value for comparison…
Well I am pretty sure that the ones that I have mentioned won’t be able to hold the claimed high (not turbo) mode in any advantageous realistic conditions.
But there needs to be a way to compare them at least, as @gravelmonkey said, a 20 C official test will be ok.
Annd who knows, maybe @ChibiM will decide some day to make a few 0C tests and see if there is a big difference in sustained output compared to 20C.
The amount of heat a light can “shed” is directly related to the temperature differential between the light and the environment.
I don’t have objective data, but anecdotally, I can absolutely assure you the output of my Emisar D4 (V1 with Nichia 219) was far lower when I was trying to use it down an underground mine near the equator at 28C+ than it was on a nighttime walk in the UK at ~12C.
I’ve always wondered if there’s a strong correlation between those who like or dislike turbo modes and the climate in which they live.
Ultimately I guess we are looking for some value to allow us to compare similar lights. The efficiency of the drive, the body design (mass, surface finish) and the LED will all impact the sustainable output, this many variables is hard to condense into a single value.
It’s not so much the thermal stepdowns that annoy me, as these are required for maximising the light at a given environmental temperature, it’s the way the output is advertised that is borderline lies.
It is just dirty marketing. Manufacturers like Fenix are not stupid . You want more lumens you get more lumens, but for how long ?
If performance is not documented, you buying a cat in the bag. If it is documented and do not work as documented it is defected. Return product take your money back.
Fenix used to put runtime graphs on its product pages. I’m not seeing one for the PD35R.
There’s no standardized way to advertise modes that throttle. Acebeam and Skilhunt have been using a format like 4300-750-400 lumens / 40s + 2h + 1h, which works fine for timed stepdowns but not so well for sensor-based regulation. Zebralight writes “PID” next to modes that can throttle, but that doesn’t tell a reader what the stable level might be under typical conditions.
I used to use a cooling fan when I made runtime graphs for reviews, but now I do it in warm, still air to match the most typical conditions. Anything cooled is a supplement to demonstrate how the temperature control works.
How HOT do YOU want it?
How hot is too hot?
Not all manufacturers and customers are in agreement as to the issue of heat.
Unless and until everybody’s on the same page there, you can’t really compare one light to another.
Some lights by design or by default are going to sustain higher temperatures. There are plenty of people in the world that think that is a “problem”.
We’ve seen this discussion over the years many times about certain lights getting too hot or stepping down too fast. You’re not going to please everybody.
All of this is one of the biggest issues in sustainable output. At least for lights where battery power is not the limiting issue.
The design plays a large part also. Surface area such as fins and head size and the ability to transfer heat into the body can make a significant difference from one light to another. Some manufacturers spend more time in this area. Of course size and weight are all trade offs.
I think all of you people who think that anything over 50 Celsius is comfortable and not that bad, are liars.
You either liars or this has to do with the fact that you never use your light for more than a few minutes.
I do.
I use it for an hour at a time and it has to be in either in my right or left hand and anything over roughly 45 to 50 degrees is not comfortable for more than 60 seconds.
That being said that Anduril 2 thing that allows you to adjust the temperature by up to 10° I think?, is a pretty would be a pretty good solution for all of us
But I think a lot of people don’t want Anduril because they come with an electronic switch, don’t they ?
and some people lights with a Mcclicky
Anduril has had adjustable temperature limits from day one.
You don’t need that UI to be able to adjust your temperature(down). Any light with enough mode options or specifically any light with a ramping mode has a temperature “adjustment” built right in.
You’ve made me realise I’m missing a vital piece of information for my desired light rating at 20C and that’s the max surface temp. So then the rating is the lumens the light is capable of outputting in 20C conditions, no active cooling and sustaining a maximum surface temp of 45C (for sake of an arguement).
Edit: note this is just a rating system and if you want to go nutz removing all thermal safety and turbo-till-desolder, then I’m not saying manufacturers are limited to surface temp of 45C, just for purpose of the rating system.
This is a good paper I found, talks about cumulative minutes above 43C:
https://incompliancemag.com/contact-burn-injuries-the-influence-of-object-thermal-mass/
Fenix still does this. Maybe not for thr older models, but their current ones do like HM55R, PD26R ACE, etc.
Well, there’s actually a lot that goes into this
If you want to focus solely on ANSI, which is the messured output at 30 seconds, on thr highest modes, most lights don’t meet their advertised spec. It’s in rare cases Ive had lights perform to ANSI spec on their highest mode and i have reviewed over a hundred lights. Fenix, Olight, ArmyTek are really the only brands that have somewhat consistently (like within 10% of) met their ANSI spec on Turbo/High.
Past that, the larger and more powerful flashlights get (more leds, higher input current) the harder it is to meet the specs at high output duebto heat (hence step downs and/or thernal throttling). Power in watts=heat and that heat has to go somewhere. As the LED heats up the output decreases, the need to throttle or reduce the current input to the LED is necessary to keep it from burning up. I had this happen to a Fenix LR80R i tested yesrs ago: the thermal regulation failed, and on Turbo it got to 120 C, melted the reflector and damaged one of the sst70s. It held really high output during that time, but overheated and damaged itself.
This is why Imalent and Acebeam use fan cooling on their highest output lights.Some cycle lights also have high thermal ceilings (like the Gaciron Raptor v2 I tested). You’d otherwise need a prohibitively huge host to manage the 700-1200+ watts produced to make 60,000, 75,000 and 200,000 lumens. Even then, stepdowns are required for the highest output levels. I’m sure companies could disable thermal throttling or raise Tmax PIDs, but that would (like anyone who’s maxxed the thermal ceiling on an Anduril light) make the flashlight unusable as it would get excessively hot for an unprotected human hand in short order.
I think for now the big brands are doing the best they can with what they have. Thr Fenix HT18RV2 i just tested maintained 3000 Lumens in Burst for 5 minutes. Pretty good.
I agree with OP. It would be nice if what was marketed as “high” was the top mode that can be sustained without rampdown due to heat.
All modes above that should be marketed as “Turbo”. If more than one such mode, maybe Turbo 1 and Turbo 2, etc.
That said, there is no uniform method of naming modes on lights. It’s all up to individual manufacturers and their marketing departments.
Well, you understand my point 
How about Max… then stupid1 and Stupid2 ?? 
Not to digress too much, how did the custom of labeling the max output as “Turbo” come to be?
My first “nice” flashlight was a Fenix with the turbo function being activated by twisting the head with the high mode activated and that was about 15-20 years ago. I think it was established then.
While we’re on the subject of misleading terminology, nobody should call a mode “turbo” unless it involves an actual turbine.
People being silly (and a bit ignorant), which is about par. It’s not really even like ‘supercharger’. I think it’s more like ‘nitrous oxide’ myself, but the marketing weasels wouldn’t like that term;-)
More specifically an exhaust driven compressor… As in turbo charger.
From Wikipedia:
“a turbocharger is powered by the kinetic energy of the exhaust gases.”
A super charger is mechanically driven.
But that is why I wondered how we got there. I have been into flashlights for a long time. At one point the term just seems to have appeared…
“Turbo mode” should make the light run worse, just like old-school PCs used for compatibility. 