Red Mag shorty 4 x XML direct drive

Flashlight Modding and DIY Parts
1

This was a fun build.

I had 4 XML’s pulled from a couple of Chinese lights that I had done emitter swaps, along with a red Mag shorty host, and custom aluminum heat sink. About an hour or so later I had created a monster parallel wired, direct drive 4 x XML torch.

Prior to connecting the stock Mag switch, I tested current and measured nearly 8 amps using a freshly charged IMR 26650 battery (gold color, not sure brand but possible King Kong). Testing current draw with the switch in line (prior to soldering) I measured about six amps. After soldering and assembly, I tested the tailcap reading and again measured about 6 amps. However, ceiling bounce test told a different story. Without the DMM hooked up, I measured 149 lux, but with the DMM at the tailcap, I only measured 92 lux. Clearly the DMM was adding resistance, so I am definitely getting more amps than my DMM is telling me.

DMM at tailcap Amps Lux
No ? 149
Yes 6.1 92


Pics of build


XML's were mounted on the heat sink using thermal paste, aligned with the 4 x optic, then glued down on the edges using arctic adhesive. Wiring was done in parallel using AWG 24 copper stranded wire.

The heat sink was constructed from two different pieces of aluminum bar stock, cut and glued together. Copper tape was used to create a snug fit within the mag head and body tube for heat transfer.

Switch wired up as direct drive




Line up of lights used for beam shots and ceiling bounce. Most of these have been modded to some degree. (Check table below for specifics)


(L to R) Sky Ray 1JC8, Trustfire 3T6, Sky Ray STL-V2, Ultrafire 7 x XML, MVP, Mag shorty (this build)




Ceiling bounce test.
All lights are on max with freshly charged batteries. Readings taken immediately after turning on.

Torch Mod Lux
Sky Ray 1JC8 5000K XML; 8 x AMC 7335 driver 40
Trustfire 3T6 3 x 5000K XML; stock driver 59
Sky Ray STL-V2 40000K XML; stock driver 43
Ultrafire 7 x XML stock 119
MVP 3 x 5000K XML; 8 x AMC7135 driver 110
Mag shorty 4 x 6000K XML; direct drive 149



Outdoor beamshots
Note: I only have a point and shoot camera with no manual exposure so these photos are not the best since my camera automatically adjust for exposure, but at least you get some idea of output. Order is same as pictured above.

2

:slight_smile:

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Awesome! Too 8) . I’m jelly!!!

5

Is that one of the XR-E 50mm 4up TIR optics? Just curious. Got to get pretty hot pretty fast? Looks like a good sized heat sink though.

Thanks for posting the mod!

Between the 24awg and the switch, there must is some limiting resistance, which is probably good with parallel, but you must be pushing at least a couple+ amps thru each one, don't you think?

6

Nice neat job on the wiring. Is that a C or D host?

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You have to be careful with wiring them in parallel like that, since those are salvaged LEDs they likely are completely different bins and thus are going to have different vfs.

8

Justin, yes optics are 4-up Cree from DX here.

As you mentioned, it does heat up quickly. I ran it for 12 minutes last night - head was way too hot to hold and the body was becoming uncomfortably warm. Design is for maximum output in a small package so running this is restricted to short <10 min bursts. Also, run time will not long since it only uses a single 4000mAh 26650 IMR battery.

I can't get an accurate read on the current since my DMM is giving resistance as well. Based on the ceiling bounce tests I can only "guess" that each LED is seeing in the neighborhood of ~2A, but I can't confirm at this time.

Host is a cut down D mag, some refer to as a "1.25D".

True, 3 of the XMLs were harvested from a TR 3T6 which was wired in parallel, the 4th was from another light which I don't recall. When I tested the setup under low voltage (2 x C NiMh), that 4th XML was noticeably dimmer, so it clearly has a higher Vf. I know parallel wiring can be risky, i.e. possibly burning out LEDs, but this was more of a "fun" and "how many lumens can I get out of a mag shorty build" project. I will say it was very easy since I already had the host and heat sink, plus not having to fiddle with wiring a driver. I'll have some fun with it, and may try to figure out how to include a low mode, possibly using a resistor and 2-stage switch. Or, I may just sell it. Any takers? Lol.

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Nice build Hill. Like Rufusbduck I love your soldering. Also the polishing on the TR3 adds a little class.

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You know its funny, this was a "quick build", that is, I really wasn't trying to make it perfect. But for whatever reason (maybe because I was relaxed and enjoying the build), the soldering joints all came out looking pretty clean, and even the wires have a nice "flow" to them from LED to LED. Thanks very much for the compliments!

I am planning on dedicating a special thread to polishing heat sink rings on lights. I've done several (the two pictured above are the TR-3t6 and SR STL-V2) and the chrome look really gives them some "bling" without being overkill.

11

Ace build, thanks for the pics.
I wasn’t aware that you could direct drive led’s ?, I assumed that would make them go pop, but obviously not as this shows.
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The more recent LEDs from Cree (XML, XPG) have lower Vf's (2.9 - 3.2V) compared to the predecessors (XR-E = 3.7V). Typically direct driving a single LED from a single Li-on cell with a voltage between 3.6 (nominal) and 4.2 (fully charged) could potentially result in flashing the LED. This is especially true with higher capacity cells like IMR's.

However in my build the 4 parallel wired XML's are all drawing from the same IMR cell. That plus the resistance from the mag switch keeps the current per LED well within spec (I'm guessing ~2A each but have not confirmed).

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I see, that clears that bit up for me, at least I know a bit more I can get on with my first mods, I have a few hosts, thanks for the info,
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