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

TrustFire AK-90 (3/4x26650, 12x XM-L T6)

Reviewer's Overall Rating: ★★★½

Reviewer's Mod Host Rating: ★★★★½

Summary:

Battery: 3/4x26650
Switch: Tail, reverse clicky
Modes:

H 100%, M 50%, L 10%, Strobe, SOS, with memory

LED Type: Cree XM-L T6 flux bin, est. 1A or 1B tint bin
Lens: Glass
Tailstands: Yes (similar to a candle lighthouse)
Accessories: None
Price Paid:

Reduced cost review sample from Wallbuys

Reg. price was $91.39

From: Wallbuys
Date Ordered: Ordered 5/29, shipped 5/31, received 6/10

Pros:

  • Very good finish for a non-black anodizing
  • Impressive throw (~42kcd) for a flooder
  • Excellent machining, well cut standard threads
  • Integrated pill, good size with a nice star mounting surface
  • Very Good heatsinking on head, good for modding
  • Decent reflector, aluminum SMO, shallow individual reflectors
  • Perfectly centered emitters
  • Good mod host

Cons:

  • Emitter centering disks block some light
  • Run-of-the-mill driver, standard modes
  • Underdriven for a 12xXM-L light
  • 4x battery extension has slightly lighter ano colour
  • Integrated pill is good for thermal transfer, but can make emitter access somewhat difficult
  • Unprotected cells only in 3 cell configuration

Features / Value: ★★★☆☆

Design / Build Quality: ★★★★

Battery Life: ★★★

Light Output: ★★★☆☆


Overview

When I spotted the TrustFire AK90 with 12 XM-L emitters with this much heatsinking, my first thought was I wonder if it will handle 100 Watts for 10 minutes? That was the modder in me speaking. Once I had it in hand, I figured it might be worth a try. But first, I need to keep it stock long enough to review it.

This is a big light! BIG! This is the biggest light in my collection, and I have the UF T90 and BTU Shocker. It's that big. I have a few comparison shots and I'll post a couple here and some more in the comments. Here is the light standing alone.

Here it is in 3x26650 configuration with the UF T90, which is no small light. The lights share a very close resemblance. The AK-90 has a thicker battery tube.

Here's another with the 4x26650 extension attached. Also known as 'skyscraper' mode.

Head on. Lots of XM-Ls (Note: I had already trimmed the emitter centering spacers, they were visibly blocking light from getting to the reflectors).

The handling is, well... long. Activation with one hand is near impossible, and a cigar grip in 4x26650 mode may be possible by X-Men's The Wolverine. Maybe.

As a weapon, this is the equivalent of a broad sword or baseball bat; two hands required.

The light comes apart into many pieces. The tailcap, three body sections, a neck piece, and the head.

Looks like I missed a thread shot, but they are fairly standard for a big TrustFire light. Fairly smooth, well cut, lubed, no anodized, and there are lots of them. It takes at least 10 turns to get the tailcap off.

In the front end of the head, we find the nicely finished bezel, O-rings, thick glass lens, and the 12x aluminum SMO reflector, and the 12 XM-L emitters on a very large integrated pill area. The reflector seats onto the stars with plastic emitter centering rings. Unfortunately, these rings extend up into the reflector a bit and block some light. There are O-rings where they should be and they appear to do their job The stars are attached to the pill surface with Fujik-like thermal adhesive.

The driver is retained with a large metal ring that presses on a plastic plate that covers the driver. After removing the ring, the plate and driver simply fall out. There are four somewhat small emitter wires, which may be OK for the driver current used in stock form. The emitters are wired in a 6S2P configuration.

The driver itself appears to be adequately assembled, but it underdrives the emitters, resulting in relatively low output per-emitter. Current sense resistors can be spotted just above the coil, at about 1 o'clock. There are three resistors, and one free spot for another resistor (hint: check the mod post down below ;) )

The tailcap is huge and is assembled in the standard fashion. Here are the parts laid out.

Beamshots

The beam is slightly ringy when white wall hunting and has a flower petal spill edge.

High:

Med:

Low:

Outdoors: (Mouse-out AK-90, Mouse-over 3000 lumen XM-L2 modded SRK)

Compared to this modded SRK, the stock AK-90 is slightly brighter with a slightly narrower but brighter spill. The AK90 hotspot appears larger and just as bright.

Measurements

Dimensions:

  • Overall Length (3 / 4 cell): 342.0mm / 420mm
  • Bezel Diameter: 89.8mm
  • Head diameter (widest point): 89.8mm
  • Heatsink diameter: 65.1mm
  • Neck diameter (Heatsink / Lanyard ring): 56.8mm / 65.1mm
  • Body Diameter: 37.0mm
  • Tail Diameter (End / Lanyard ring): 39.5mm / 51.1mm
  • Reflector Inner Diameters: 21.4mm
  • Reflector Outer Diameter: 79.4mm
  • Reflector Depth: 17.1mm
  • Reflector Emitter hole Diameter: ~8.5mm
  • Lens Diameter: 83.6mm
  • Lens Thickness: 2.85mm
  • Emitter stars diameter: 16mm
  • Driver diameter: 44.8mm

Weights (without batteries):

  • Overall: 964g
  • Head: 518g
  • Body Tube/Neck: 366g
  • Carrier: 80g

Performance (stock, 3x26650 , uncalibrated measurement equipment):

  • Light Output * : ~3507 lumens at start, ~3522 after 30s (increases for first 25 seconds, then starts to slowly decline.)
  • Beam Intensity: ~42kcd
  • Med: ~1701 lumens
  • Low: ~258 lumens

Output is very similar on 4x26650 cells.

* Note: Measurements taken after modifying centering rings, max output was about 300 lumens lower in stock form

Power Source Options: 3x26650/18650 (unprotected only), 4x26650/18650 (protected or unprotected)

Switch type: tail, reverse clicky

Modes 12.2V supply: High (3.21A), Medium (2.02A), Low (0.52A), Strobe, SOS

Mode Memory: Yes, mode memorized when powered off for more than ~three seconds

Conclusions

The TrustFire AK-90 is a well built light that suffers from being underdriven and emitter centering rings that block about 9% of the available light.

As shipped, this light is recommended for those that want around 3000 lumens from one of the longest lights available (only a 6D Mag is longer).

As a mod host, Relic Recommended. This light begs for a mod, it cries for more juice. I suspect it can handle a lot more power, and I plan to find out someday.

Thanks for reading! searchID8934

July 24: Resistor Mod!
I had a question about resistor modding, so I decided to take a couple of minutes to see if we can quickly get this up to 5000 lumens. Short answer; it does not disappoint. :party:
The sense resistors appear to be on the input-side, meaning the driver regulates by monitoring incoming current, not the emitter current as most drivers do.

I’m not 100% confident in it, but the driver still seems to be managing emitter output power quite well. In any case, the mod for this is quite similar to the usual resistor mod; make the overall sense resistance smaller. This means more current must flow to create the same voltage, therefore more power. Yum.
OK, we have an unknown value there right now because two resistors are hidden under the R620s, and I’m too lazy to take them off the read them. So, I’m gonna guess. :smiley: The new resistor will go in the empty spot, marked as ‘R12’
Edit: Upon closer inspection, there are no resistors under the R620, which makes sense after I calculate the gains arrived at with the resistor mods.

Let’s try a 0.5 Ohm (R50):
Total output: 4910 lumens after 30 seconds
Tailcap current: 4.9A
OK, not bad at all. Driver gets a little hot but seems to cope with it for a while. Probably as long as the host can; it gets hot quick. I’ll add a heatsink to them anyway.

But wait, the added sense resistor is getting way too hot. It should be much larger to handle the current.
So I’ll make an R44 using two R22 resistors in series. J)

Total output: 5150 lumens after 30 seconds
Intensity (Throw): 47kcd (433m)
Tailcap current: 5.4A
Over 5000 lumens, I’ve reached my goal! Gets a little toasty though. Tailcap currents are with 3x26650. I didn’t try with 4x26650, but output should be the same or very slightly less.
Also, the head sections need thermal paste on the threads to improve thermal transfer. I didn’t show it in the review, but the reflector portion and the heatsink/driver portion are threaded together. If you have the capability, you might want to strip the ano off those threads to make it that little bit better. I just went with the thermal paste for now.

The host will cope better with a little lower output, maybe 4500 lumens or less.

Driver Heatsink

I ordered a variety of heatsinks from Fasttech a while back just to have them on hand. Here’s what I did.
First I hold them in place on the MOSFETs/diodes to see what cutting is necessary.
Trace a line onto the heatsink.
Cut and grind heatsink. Ensure clearance from inside of head.
Lap bottom to remove the ano (not necessary, just wanted to do that).
Clockwise from top left: intact heatsink top, intact heatsink bottom, cut heatsink, cut and lapped heatsink

Now all I need to do is Fujik them onto the MOSFETs and wait:

I was able to move the caps and coil without desoldering or extending them them, they had longish leads. I could have extended the leads and added more heatsink but that sounds like more work, so…
This should help a little with the heat. The driver has a cavern to live in, so there is lots of space to radiate into and it should transfer some heat. The top of a chip isn’t the best place to have a heatsink, but it’s better than nothing.

Happy Modding!

July 4. Happy Independence Day to all our US readers.
Here are some side-by-side shots of the AK-90 with some other big lights I have.
AK-90 with T90:

AK-90 with DST:

AK-90 with 3D Maglite:

AK-90 with TR-3T6:

AK-90 with BTU Shocker:

AK-90 with LusteFire 3XU2-X3:

AK-90 with YinHex YH-X9:

AK-90 with SRK:

AK-90 with SK68 clone:

thank you for th review, it seems that it has about the same output as some 5*xml or 7*xml lights have? unmodded.

Yeah, that’s about right. it’s in the ballpark of the 7x and 9x XM-L lights. Mostly due to the driver. I guess they do not want to spend a few bucks to put a beefier driver in there. On the plus side, run time will be great in 4x26650 mode. :wink:

thanks for the review. i love these high multi lights, i own the ak47 modded by richie that does 6000 lumens at around 90 watts.

let us know when you figure out a way to modd this bad boy.

So which multi emitter light do u think is the brightest as of today? Sub $100 that is. :slight_smile: should I just be content with my King?

I don’t have a 12x but I have a 9x a 6x a 5x I had a 7x. Of them the only one that I think really is worth the extra money is the 9x. It’s a 9xT6 trustfire and with king kongs it seriously rocks and it’s no slouch with unprotected 18650’s either. I modded one by de-doming 5 of the emitters and putting in heavy wire and copper on the springs. I just sold it but man was it a nice light. Nice tint with the de-domed and extra throw and with the heavy wire and copper on the springs it had as many lumens as it did stock. I have another one that it now waiting to be modded. I thought about putting in an even more powerful driver but I just don’t think it will be worth it. On high it’s already getting hot fast enough.

Thanks 18. I was eyeing the ebay auctions on those but they have stopped all auctions now.
And sorry for the otp relic. 0:)

Read this before you order this.

Overall, the SRK is tough to beat. It’s compact, most put out 2000 lumens stock, and uses four batteries which gives a decent run time.
In fact, when comparing to long plunger lights like this, it is not really in the same class.
Now, if you just do not care about the length or format this one offers a lot of potential. Unfortunately it is untapped in stock form. It will give about 50-60% more light than a stock SRK. That will be noticeable, but not a slam-dunk “wow that is so much brighter” kind of increase.
Figure out a mod for this to get closer to it’s full potential? Now we’re talking :smiley:
I have an idea or two for this, I just need time to try some things, probably after the DIY build is done.

I added some more side-by-side shots, they are in the first comment
A little something to help gauge the size of the AK-90 :slight_smile:

Nice work, Relic! I love that first pic of the light.

I'm shocked at the kcd this puts outconsidering the tiny reflectors. Modded for higher output this would be a real knockout!

Thanks JM, I was pleasantly surprised by the throw. I expects 25k, 30kcd tops. After modding this might hit 60-70kcd, which would be quite the throw for this class of light. I wonder what 12 dedomed XM-Ls would do for throw? :smiley:

Simply replace all the XM-L with XM-L2 U2 and you will easily get over 4000 lumens… wait, that would be a whopping $80 mod!!

I thought of putting them all on direct-bonded copper stars, but the thermal test shows not much thermal sag in the first thirty seconds. I may skip that and save myself $30-$40.
Although, each emitter isn’t driven very hard right now. Once I bump it up things might change.

Any temperature reading of the head after a long run on high? How would you compare it to this one by the looks?

http://www.fasttech.com/products/1601/10005076/1398602-trustfire-tr-j20-12cree-xm-l-t6-5-mode-8000-lumen-

this one uses 3 batteries with no extension tube though, and 5 bucks more than AK-90. Have you look up to the specs of the fets. Would it be possible to beef it up by changing the sensing resistors?

Relic, can you take a photo of the IC which is right under the coil edge, the one with 10 pins?

Thanks for the review.
Nice driver.
Has the driver a under voltage protection? That is a thing I miss in these multi emmitter lights.

How is the tailcapcurrent with 4 cells compared to 3 cells?
When will you mod the resistors?

Very nice review!
Thanks for sharing!

I have not done a thermal test on this one yet. I did notice that it warms up fairly quick. The head is two pieces, and the emitters are mounted on the front piece. This means that there is an interface between the main heatsink and the emitters, which is not ideal. I added some thermal compound to the threads there and it seemed to help even out the temperature difference quite a bit. I’ll do a thermal test at some point.
The TR-J20 looks to have MUCH more heatsink surface area, and possibly more mass too. If that one had been available at the time of my AK-90, I would have got the TR-J20 instead.
The MOSFETs and diodes have no markings that I can see.
Resistor mod is definitely doable for more drive. How far it can go is unknown. Hopefully a lot J)

The next time I have it open, I grab some more shots of the driver. I recall all chips have no markings, so I doubt it will be identifiable.

I’ll check the low voltage battery protection and update the review.
Output on three or four cells is virtually identical, and tailcap current is altered as expected (lower on four cells). I measure it the next time I work with the light.
It will be a while before I get to mod this one.