I think if u want such light it would be alot bigger then any big light today, acebeam x70, olight x9r, none can do 10min max or even close, the heatsink and bodyhost would be so big it would be like carry a rocket launcherā¦ i guess we arent there yet to build compact lights that can sustain highest that longā¦
led technology can not get over 50% efficiency so half the power is heat however efficient your led, not much you can do about that. So a 200W flashlight will need at least 100W cooling power to keep on going.
The original GT can sustain turbo ,mine has never stepped down.
yes but we talk lights with 20kish lumens or more with multiple xhp70 emitters that generate tons of heat, no light on the market can do that afaik without serious active-cooling.
the original gt does not even 2000lumens so for that big host its an easy task more or less.
I noticed that your collection listed above doesnāt include the MF04? From the reviews Iāve read and the light I own, my understanding is that it has no step down period. Iāve not completed a lengthy runtime test but in my use so far on very cold days (around ā15C) the MF04 has remained at full output for at least half an hour.
I also believe that the GT (not GT70) is of the same specs? Single XHP35 Hi which limits overall output but allows the light to not overheat and force thermal protection?
For a serious response to your practicality inquiry:
I love my MF04 for the insane throw and constant turbo output but the trade off is a severely focused beam with barely any usable spill due to the limited overall output. That all adds up to a very fun super long distance searchlight that has so little spill I almost canāt see where Iām walking in the dark.
The XHP70.2 versions of super throwers provide similar throw with a larger hotspot but most importantly a lot more back end spill caused by that giant leap in output. The trade off is the massive increase in heat production which simply canāt be avoided when the specific goal of the light is to maximize output. Sure, flashlight manufacturers could build a light capable of 20k lumens thatās limited on turbo to only 5k and has no stepdown but the market would be almost non-existent. If your primary goal is a super thrower with long runtime then youāre going to have to sacrifice your desire to run turbo all the time. If the GT4 will have over 20k lumens max, then itās likely the turbo stepdown or high mode will have a sustained output in the range of 3-5k lumens.
The GT only has 2k lumens and the MF04 only 2700k lumens which means there is a possibility you could double the max output of either of those lights sustainably with the GT4ās med or high mode.
HOWEVER: Since Iāve been buying flashlights with output 65x that of the best maglight available only 15 years ago Iāve been asked countless times: āyeah thatās cool but whatās it for?ā. The truth is that there is no actual practical need for 60k lumens or over 2.5km of throw. Itās something we want, not something we need! Thatās just like asking why cars that cost over $100 000 now typically come with 700+ HP when a prius with 85HP (or w.e) will easily tackle city driving.
Kinda like this bad boy!? :smiling_imp: :smiling_imp:
OptoFire build (BLF)
How can we keep them cool? EASY when youāre making a rocket launcher! :smiling_imp:
According to FREEME the MF04 HAS as step down:
Initial test result for ASTROLUX MF04 Runtime in TURBO mode at 29Ā°C/ 84.2Ā°F ambient temperature. Mini usb box fan was used to provide light breeze for the light at 30cm distance.
Temperature was about 43Ā°C/ 109Ā°F at about 5.5min mark. There is definitely room to sustain the high output longer.
Did a runtime test for MF04 (prototype) with four pieces of SONY US18650VTC6 3000mAh 3.7V 18650s. MF04 output dropped to 63% from 100% after 8mins, and stayed plateau for another 110mins or so before shutting down itself. Total runtime in TUBRO mode was about 2 solid hrs (126mins) based on 4x 3000mAh rated cells.
Runtime for other levels will be included in soon.
T1) Attempt to re-trigger TURBO after about one minute from first automatic stepdown.
T2) TURBO re-triggered for the second time.
Event A) Discovered that my cooling fan was blowing off axis because the cable got caught with the door when closed. That could probably explain why first stepdown occurred few seconds earlier. Output increased by 5% (peak) after cooling was restored.
T3) Has slightly shorter TURBO duration compared to T1 and T2. Could be due to temperate controller restricting the output.
T4) TURBO re-triggered for the fourth time after 3min interval from previous stepdown. TURBO is able to sustain for approximately 2mins when it was given more time to cool down.
Link below info in bottom of Post #2.
That step down STOPPED me from buying it. Not sure why I considered it when my TN42vn90 BLOWS it away in output[ 5000 Lumens], continuous TURBO. and matches its throw[1.05Mcd] :+1: In the fall, winter and spring I can use turbo until battery depletion, ~ 25 minutes. In the summer I can get 10 minutes of constant TURBO,Put on Low 3 or 4 minutes and then bump back up. There is a thermal step down that has never been activated. The light just gets hot and I manually lower output.
Either FREEME is wrong[I doubt it] OR you just do not notice it OR it could be a thermal step down which he does not mention.
Just came up with the second practical use Iāll have for this light
That is exactly what Iāve read everywhere about the MF04S (XHP70.2) not the MF04 (XHP35 HI).
MF04S competitor GT70
MF04 competitor GT
MF04S 6k lumen 1km throw
MF04 2700 lumen 2.5km throw
It is far less practical then you would think.
There are many reasons for this but a few off the top of my head, HID works very very different then LED.
1: you need much less power with HID for an equal throw distance to start with, that is less heat as the baseline.
2: Most of the heat from an HID is expelled out the front of the light like an incandescent, there is minimal heat transfer to the body of the light with HID. An LED on the other hand has most of the heat transfer directly to the body of the light.
3: A high powered light such as the GT4 will use around ~400w of power all said and done. Keeping this cool passively is basically impossible. This is what is needed to properly cool just 10w passively: https://www.ebay.com/itm/1pc-10W-Watt-LED-Aluminium-Heatsink-Round-/153110532098
4: the GT4 with 8x 18650 cells will be drained in about ~12 minutes. So even if you could cool the light, it would hit LVP in under 15 minutes anyways just from running out of power.
5: You can disable the thermal control on both the GT70 and GT4 and run it as long as you want at full power but it will of course get quite hot doing this.
Overall, if you want long range throw for extended use, you will not beat HID. This is where they shine since the warm up and other issues of HID are not a concern for this. I have never said otherwise.
LED is better for the basic hobbyist since there is no warm up and it is better for short term use.
Look at the link that I provided in Post # 372. That STEP DOWN is under the review of the MF04!,Bottom of Post #2
Obviously I do NOT have nor want the light,mostly based it on FREEMEāS FINDINGS and my TN42vn90 is a much better light for reasons I already mentioned.[more expensive, I know]. 
lol upon further review it seems I was trying to defend my light more than I was taking my time to actually read the review link. :person_facepalming:
I can only hope that the āprototypeā he tested was not as good as the final product but thatās highly unlikely. 
Iāll try to do a runtime test myself one of these days.
Did you buy your TN42vn90 directly from Vinh?
Iām bugged to see people qoute the MF04 as having 2700 lumen. Thatās marketing BS. It uses a xhp35-HI just like the GT. Itās actual lumens are about the same as the GT, around 1800-2000. The GT pushes it to 2.5A while the MF04 pushes it a bit harder, I think 2.7 to 3.0 so it squeezes out maybe 100 to 150 more lumen. Not that big a deal. Thanks.
Of all the reviews Iāve ever seen where guys test output in their own lumen tubes ONLY the BLF series of lights actually meets or exceeds the actual specs from the manufacturer.
I go out of my way to make that happen and glad people have noticed.
I thought of 2 more throwy lights with sustainable high ouput performance. Itās not 20k lumen, but more like 7,000 or so. Kind of odd lights, but I thought Iād mention them.
The Storm of Ra $354 is an active cooled light with a xhp70.2 and a big āol lens on the front. Itās supposedly 600Kcd which is 1550 meters according to ANSI FL1 specs.
Then there is the Lemax LX70Super which is also a xhp70.2. Itās rated at 4,250 meters! Lemax makes all kinds of throwers and searchlights, some with led and some with HID. They are all very expensive, though.
Probably the big deal in throwers currently are these new laser excited phospher emitters. Instead of using an led to make the phosphor glow bright, you can excite it by shining a laser on it. It makes for a very small, but intense light source that can be focused to very long distances and it generates way less heat than an led.
I think there are 2 3 of these on the market so far. The Maxtoch XSWORD L2K, the Weltool W3 and the Acebeam W10. They are all relatively low power and produce a very thin pencil beam of light very long distances. They are very compact lights as well. In the next few years we should start seeing bigger versions and hopefully the costs will come down. Right now they are a bit of a niche product.
MF04 pushes out more Amps then the BLF GT? are you sure? because i think the MF04 uses the same driver as the MF02, and the MF02 with Lexelās NarsilM 2.5A 12V buck driver drives the light harder then stock, what i thought was that the MF04 uses the same driver as the MF02 and the MF04S uses the same driver as the MF02S, correct me if iām wrong
Same driver, but itās pushing the driver harder than the MF02.