Review: TrustFire AK-90 12xXM-L T6 3/4x26650 Flashlight

Relic, have you thought about de-doming the center four LEDs? They don’t have much reflector anyway, and there would still be the surrounding eight for spill. Seems like a good way to turn it into the ultimate combination throw/spill light.

Actually, I’d dedome the ones with the most reflector. Dedoming adds throw on the premise that more light hits the reflector and gets sent forward.
So, dedoming four alternating emitters in the outer ring might be an interesting idea for increasing the throw. Not sure how the mix of emitter tints would look though…

My good sir, there is but one way to answer that quandry. You have the skills. You have the equipment. :wink:

I thought that the dome on an LED served to diffuse the light into the reflector and throw spill out the front of the cone, and that de-doming caused the LED to fire it’s photons mostly straight-out. And I thought that the tint was a function of the makeup of the diode.

Thanks for the post R86, gives me an idea for my Gold SRK :wink:

The way I understand it, the dome acts to focus light where typical users (lighting fixture manufacturers) want it to go; in an approx. 120 degree emitter beam. Without the dome, light leaving the emitter surface leaves at almost any angle. This results in a virtual 180 degree emitter beam. This widening of the beam means those wider-firing photons head for the reflector, which puts them into the hotspot.
The side-effect of lower overall output has been attributed to reflector loss, since more photons are hitting the reflector, more are being absorbed as well.
I’ve tested a bare emitter before and after dedoming and it lost 64 lumens. In a reflector, before and after it lost almost 250.

Per the below thread by DrJones, the beam pattern of domed vs dedomed is about the same for most emitters. Both have approximately lambertian patterns.

If I understand it correctly, the increase in throw is due to the light at the focal point (dead center of reflector) being more intense.

WOW flashlighthouse ty for the review
I’m evaluating to buy it (also)for fishing(as attractive light) on the night
maybe connecting it a 12v Pb battery bypassing the driver and and regulating the 6S2P at ~19v with that cheap DC-DC boost?

any con on regulate the leds by volt instead of amp?

I would not recommend voltage regulation for this. As the emitters heat up, their Vf will drop and they will get more current. It is a positive feedback loop, and could end badly. Current regulation is best for LEDs.

how many mm of aluminum have the dropin under the leds? with the heat dissipation of this dropin will be possible to run the flashlight at 120w some minutes or seconds? it have adaptor for 2 batteries?

I have the trustfire j18 with 6 leds and more tan 60w and it have good head dissipation it have around 7.5 - 8 mm of aluminum under the leds

now im looking for some good 12 or more xm-l host for drive it too with some pwm and external high power mosfet and 60·C termostate
like this

Ty didn’t know that heat drop the Vf, do you know approximately in what proportion?
But I could play with the volt and find a perfect value that keep the body at ~55 C
My idea is that using an external “driver”(volt regulator in that case), will not have the 20% of heat lost by the driver inside the flashlight body, and so drive the led a bit harder

Assuming that I can keep the heat low and constant, there are other cons using a V regulation?

I cannot recall how thick the emitter plate is, but it is fairly thick. The limiting thermal factor is the head is two piece, with the emitters on the front piece and the main heat sink on the back piece. That interface is threaded but there is a measurable temperature difference between the pieces.
I recall XM-L having a –1.5mV/degC Vf drop. Other than thermal runaway, don’t think there is anything else seriously negative about using voltage regulation.

really no way to fit it with only 2 26650 without the extensors? with 3 batteries maybe are too long for me

someone know how many mm of aluminum have this flashlight under the leds?

Hi Relic,

When you did the resistor mod, did you use 3 or 4 batteries after the mod? I bought another AK-90 light just for the extension tube for my modded light. Now I have a stock AK-90 but I can only use 3 battteries. Would it be ok if I use the r47 resiator with only 3 batteries?


Pardon my laziness, I scrolled through and found my answer! Lol.



Maybe (2) 16340? :open_mouth:

no, I want run it with 2 x 26650 with other driver.

2 x 26650 dont will fit without the extensors ?

this one its the same host?

i must decide what multiled host to buy and need to know if 2 26650 will fit in this host without extensors or not

the reflector of the ak-90 appears to be nice. its possible to reduce the diameter to77.8mm without affect the reflective area of the reflector to have the chance to use this reflector in other host like this?

someone have this ak90 and have too the trustfire tr j12 or tr j18?

the tube for 2 batteries of the tr j12/tr j18 fit with the head of the ak90? (I want use the ak90 with 2 batteries )

I have cupon discount and must decide what multiled buy today or tomorrow

edit: too late i have buy other flashlight :frowning:

The one I have, which may well be a clone of this, has 3x R620, rather than 2xR620 + 1R5
You can see it here:

Anyone know wow that is likely to change adding a fourth resistor?
I’m guessing that as overall that’s less, I might want to add another .620 or a little bigger?

I just ordered myself one of these:

It sort of resembles the TrustFire AK-90 as someone already pointed out. I am curious if it is anywhere near 9000 lumen… Or should I expect closer to the AK-90?

So is it roughly 75w, or closer to 89w ? Hm… The LED’s are 10w each at 3a? 3.1v? 120w(10x12), so how do I know what they are putting out ?

I am confused. Is this perhaps 80w ? 120w\3a x 2a ? I also see the LED’s are rated at 1040 lumen@ 10w that would be over 12000 lumen if they got enough power.