Low voltage LED options for the FM C-cell “C” bodies w/ SF KT-2 TH **More Beamshots**

[Justin Case]

So as not to excessively hijack Kestrel's thread, I will just mention that I finally built the 4P K-bin MC-E AW tower using a GD1000 boost-buck driver (250mA per core), all installed in a KT1/2 TH on top of a FiveMega 3xC body. Power supplied by 3xAccupower LSD NiMH cells, total resting voltage of about 4.03V.

Got a tailcap draw of 0.865A, hot spot lux of 4700 lux, and midpoint spill lux of 130 lux. Swapping the tower into an SRTH, I got 5000 and 130 lux. In comparison, a 2S2P K-bin MC-E AW tower driven by an SOB1000 buck driver (500mA per core) in a KT4 TH measured 6500 lux and 230 lux, respectively for hot spot and midpoint spill. The same tower in an SRTH measured 7400 and 220 lux. A tower with an SSC P4 U2SWOH-bin instead of a K-bin MC-E in an SRTH measured 13000 and 70 lux.

I'll post construction details and beam shots later in the Homemade and Modified Lights forum.

 

[etc]

Great thread..

M30 on 3xC does look a little brighter than M60...

As I said, I run M30 on 3xAA and at first, the alks are pretty bright but diminish quickly. Of course it rocks on 3xAA L91 Lithiums.

 

[Kestrel]

Great thread..

M30 on 3xC does look a little brighter than M60...

Thanks for the :thumbsup:.

re: the M30/3xC in this thread appears brighter than the M60/2x17500.
I know, I've been wondering about that exact observation in the 'underexposed' beamshots for quite some time now. Besides the possibility of an underachieving M60 (an older model that I have photos of here (the one on the top): https://www.candlepowerforums.com/posts/2943772&postcount=18 ) or an overachieving M30, my other guess is as follows: The tint of my M60 is on the warm side, while this particular M30 is rather cool. Perhaps it might be a tint artifact that photographs differently in beamshots? (I'm only using a point&shoot Canon - set to manual - which tries to outwit me if I'm not paying attention.) Needless to say, I am not able to differentiate the brightness between the two Malkoffs visibly, but the photos suggest differently, as you've observed.

At any rate, the M60 I am using for a standard in this thread is a beautiful thing during actual use, the best of the five Malkoffs I've seen.

Edit: I know that the optics are different, but the older M60's supposedly have an optic that provides a smaller hotspot with possibly higher lux. Geez, I don't know... Your opinion on the hotspot size in the pics?

 

[Kestrel]

As I said, I run M30 on 3xAA and at first, the alks are pretty bright but diminish quickly. Of course it rocks on 3xAA L91 Lithiums.

I've been trying to pursuade a machinist friend of mine to make a 4xC body for his (used to be my) M30. It should be ~280 lumens at that voltage (as measured by MrG on a benchtop power supply). It would also make for a great baton.:huh:

 

[ElectronGuru]

I've been trying to pursuade a machinist friend of mine to make a 4xC body for his (used to be my) M30.

How about cannibalizing a Mag 4C tube? Then all he has to make is a M30 -> Mag tube adapter.

 

[Justin Case]

That's a good idea, but I suppose it might also depend on whether you like a tailcap button or a side button.

 

[Kestrel]

How about cannibalizing a Mag 4C tube? Then all he has to make is a M30 -> Mag tube adapter.

The thing I really like about these FM bodies is that they take a P-series bezel so well, and that the threads on the head & tailcap are really nice, much better than the tailcap threads on those other bodies.:green:

Edit: You know, thinking about an FM 4xC and then looking at 26650's like in this new thread (3.7v nominal, 4000 mAh LiMn), https://www.candlepowerforums.com/threads/232520
What would things be like with an FM 4xC body, three of the above would fit perfectly in a body of that length. There was much gnashing of teeth when the 3300 mAh LiIons left, 3x26650 has approximately the same watt-hours as 4xC(LiIon), but in a safe chemistry. If you could live with the length of a 4xC host, this would provide ~45 watt-hours vs ~20 watt-hours from 4xC alkaline.

:thinking: Now if someone had a FM 2xC that, when cut down, could fit one of those 26650's (diameter still could be the issue), that would make a great single-cell host and would blow away the AW IMR26500, providing 80% more runtime over the single 26500 for only 15 mm more body length. It would also provide ~40% more runtime than 2xC alkaline, and would be 35 mm shorter.

Ahh, the advantages of high voltage that I've eschewed for this build...

 

[Justin Case]

Here is a size comparison of a 2C and 3C FM vs a 2C Maglite:

 

[Kestrel]

Here is a size comparison of a 2C and 3C FM vs a 2C Maglite:

That's a very nice comparison pic, thank you.

 

[Rat6P]

Bump from the past, but was just wondering if there have been any more developments in this area.
I am a big fan of the 2 cell format and these FM bodies are sweet.
How does a M31 fare in the 2 C body.

On a similar note I have been experimenting with similar dimension lights. I picked up a FM Megallenium 26500 x 2 and a custom module for Lumens Factory Seraph P7 TH. The driver is the same 3 mode that LF run in their 4.2v modules. The led is still a P7 with that beautiful creamy neutral tint LF have.
A great mod for what I wanted. Obviously not a thrower like the high voltage P7 module but it puts out as much light or more as a similarly driven xpg.

I have been thinking about an MD10 with an M31 driver for a normal M3 bezel. I have a spare bezel lying around and it looks good on the FM body.

 

[Kestrel]

Hey there Rat6P. :wave:

Bump from the past, but was just wondering if there have been any more developments in this area.
I am a big fan of the 2 cell format and these FM bodies are sweet. How does a M31 fare in the 2 C body.

Probably pretty well - I really like the M31 since it is considerably better than the M30 in a number of respects. The thing is that I eventually sold off these setups of mine since I wanted to get away from the 'C' form factor - 18650's and Eneloop AA's are really nice and have gotten the bulk of engineering improvements by various manufacturers. I do agree that these FiveMega bodies seem to be extraordinarily well-made, the only bodies I've seen (personally) that were considerably nicer than any of my SureFire hosts.

Edit: Looking back at those beamshots, I do miss that throw a little; I don't have anything that does that quite so well ...