The SF M6 X-LOLA: 200 lumens for 2.5 hours

[js]

I'm probably going to get jumped on from a great height here, but I'm afraid I can't see the point of this at all. The whole point of the M6 is that it is very bright. What on earth is the point of putting a low-power bulb in it? All you get is a clunker with a dim bulb. If runtime is the concern, what is wrong with carrying a smaller light and some spare cells?

"The whole point of the M6 is that it is very bright. . . ."

Well, actually, I don't think that is the whole point of the M6! For starters, it is more than just small and bright (with MN21); it is rugged. The shock isolated bezel is the best of its kind. You can drop the light (turned on) head first onto concrete and not break the filament.

Next, it is ergonomical. i.e., it is a joy to use and handle. It is most emphatically NOT a clunker. Even with a blown lamp and no possibility of lighting up, it's still a nice light to handle. What I'm saying is that if someone had never seen an M6 at all, never handled one, and got a chance to do so at a SHOT show with the stipulation that he or she not turn on the light, most people would still jump at the chance. I know I would have! It's not a clunker at all. It's significantly smaller than a 2D maglite, and not much larger than something like a PT Surge. The rear activated LOTC allows for an overhand grip, and allows you to easily activate the light in the dark, or when wearing gloves. Plus, it can be locked out for transport or carry in a pocket. You can actually walk around with an M6 stuck in a front or back pocket without too much discomfort. Granted, I wouldn't want to take a long hike this way, but still, the point is that while its not an EDC light, it's still pretty nicely portable. It's not a clunker.

"What on earth is the point of putting a low-power bulb in it? . . ."

Well, the point is RUNTIME. More than twice the runtime of the MN20, and more than seven times the runtime of the MN21. Also, the point is a flatter discharge curve of the 123's due to the lower draw rate.

"If runtime is the concern, what is wrong with carrying a smaller light and some spare cells?"

Which smaller light? Which method of carrying spare cells? If we're talking SureFire's, I'd say that it's about a tie between an M6 alone, or an A2 and a spares carrier. Or a 6P or E2e or etc. and a spares carrier. You'd have to carry at least four extra 123's to get significantly past the 2 hour mark in most cases, although two extra 123's and an E2e would get pretty close to 2.5 hours. The spares carrier also has room for an extra lamp of course, so two extra 123's in a small waterproof container and an E2e would be easier to carry than an M6.

So, there are definitely some scenarios here, I admit.

But . . .

At what cost? 80 lumens from an E2e or A2 for 2 or so hours. vs. 200 lumens from an M6/MN15 for 2.5 hours. And the M6/MN15 would hold siginificantly flatter discharge than an E2e--i.e. it will stay white and bright longer. It's essenitally flat for the first hour, and stays at a very pleasing CCT (whiteness).

What about LED lights, you might ask? Well, you'll notice that this is in the incan forum. Outdoors I am a confirmed incan guy. I much prefer incandescent light to LED light for outdoor use, especially in the woods and fields.

And, the other point, is throw. Despite the very reduced output relative to the MN21 HOLA, the M6/MN15 throws very, very well. It's a great beam. Not my favorite (that would be the MN20) but close.

It comes down to the question of how much light is enough. It comes down to individual preference and varying use patterns. For me the M6 with MN15 X-LOLA is a GREAT addition to the M6 package. To get 2.5 hours of good light from a torch the size of the M6, . . . well, that thrills me. My TigerLight with premium pack and Gen4 LA is somewhat brighter and throws somewhat farther, BUT only runs for 66 minutes. The 2.5 hours is great for certain situations.

Plus, if you already own an M6, we're only talking another $30 to get the MN15 LA. A lot cheaper than getting the KL6 LED head! And has great throw and true color rendition, --performs better in outdoor conditions, especially rain and fog.

So, that's the point. I hope you don't feel as if you have been jumped on from a great height, but I did want to give a try at answering your post point for point.

[DM51]

js, another great reply (along with LED61's). Thanks - I am now a convert to this idea.

[js]

DM51,

Thanks! I like the setup (obviously), but it's definitely not for everyone.

It's funny, though, over my flashaholic addiction . . . err . . . I mean career, I have gone backwards in light output. I used to really get into a whole lot of light. When I made the first Tiger85 800 lumen TigerLight mod, it was my favorite light for a while. Funny, too, I mentioned that I had used it out on a walk and SilverFox was like "it must have been a short walk." LOL! (It was). Then I prefered the Tiger11 570 lumen and/or M6 with MN21. Then as a TigerLight consultant I got to correct the focus/potting of TigerLights standard 275 lumen lamp and my work resulted in the specs for the Gen4 TL LA (link below in sig line) and I really got into that due to the 66 minutes of runtime and long throw. At about the same time, too, I fell in love with the MN20 LA and stopped using my MN21 except for testing of M6-R packs. Then finally, I stepped back even more to the MN15. The 200 lumens from this lamp aren't going to WOW! you or blow you away with sheer output the way a Mag85 or Tiger85 will, but it's definitely enough light. In many cases, less is more, that's for sure. And the beam is more aesthetically pleasing than the Gen4, and more white (by a little).

But, it's certainly not for everyone. Sometimes you just need more . . . more output, more thow, or more flood (or whatever). Sometimes you just don't need much runtime, or want the smallest size for a given output.

So it is what it is, and for some, that's pretty cool. For others, its not what they need or want. It's all good!

[leukos]

It's funny, though, over my flashaholic addiction . . . err . . . I mean career, I have gone backwards in light output. I used to really get into a whole lot of light.

I concur. About 100 incandescent lumens seems about right for most of my outdoor adventures. I'm also quite excited about Lumens Factory lamps for C and E series lights. 50 lumens on a 17670 for 110 minutes.

[SunStar]

I'll just verify (as others have) the positive aspects of the M6/MN15. This is a great set-up for extended walks in the woods or camping. I will also confirm that the M6/MN15 puts out close to 200 lumens based on comparisons with the M3/MN15 (primaries) and the M4/MN15 (17670's). The discharge is very flat and after running the MN20 and MN21 driving the voltage of primaries to slightly less than 3.0v, I've then re-installed the MN15 and still get that very bright, white beam.

If I were SF, I would be supplying 3 lamps with the M6. It is brighter than the M3T, easier on batteries than the M3T, has a flatter discharge than the M3T all provided in a package that is the same length as the M3T (although slightly more bulky).

Kudos to JS...

[OutdoorIdiot]

I'm probably going to get jumped on from a great height here, but I'm afraid I can't see the point of this at all. The whole point of the M6 is that it is very bright. What on earth is the point of putting a low-power bulb in it? All you get is a clunker with a dim bulb. If runtime is the concern, what is wrong with carrying a smaller light and some spare cells?

That sort of question did occur to me, too, before I ordered an MN15. After all, when I'm heading off into the wilderness and don't want to be carrying much weight, but still want to be able to see a long way in the dark, I take a Streamlight TL3 in addition to a small headtorch. And a TL3 with spare batts is, roughly speaking, half the size and weight of an M6.

I'm not yet sure how much actual use I'll get from an MN15 in an M6, or how it performs compared to a e.g. a TL3 (anyone who has both - have you compared them yet?), but it will be interesting to find out.

That doesn't change the fact that it's great to have another output option for the M6. On the occasions I pack an M6 for its huge output it's nice to know I can also make it last for 2.5 hours with less output should the situation end up requiring it. And one of the particularly great things about this new option, to me, is that it means there are now (nominal) "125", "250", "500" lumen bulbs - i.e. each one is roughly double the output of the last. That's very, very nice, and is in line with how we keep being told our eyes work. It sounds like the new MN20s probably won't be quite double the output of the MN15 in practice, but still, the numbers are nice!

[js]

SunStar,

WOW! Now that's some good info! I love it! You can run the MN21 down to not-so-great whiteness, switch to the MN15, and still have a pleasing beam despite the state of the 123's. Very, very cool. I wouldn't have thought to test that!

And thanks for your kind words. The interest in this setup has definitely surpassed my expectations. Apparently there are a lot of people out there who, like me, appreciate the runtime and flatter discharge curve, and who appreciate the advantages to be had in dialing back the total output for walks in the woods, camping, etc.

[OutdoorIdiot]

js, just a thought, given that some of the old MN20s were blowing up, presumably due to being driven a bit too hard(?):

How confident do you feel that an MN15 in an M6 is "robust"? I am particularly thinking of freezing temperatures, here, i.e. what might happen when an overdriven MN15 is first fired up from a very cold temperature. Is it cold where you have been testing yours?

I suppose this question also goes out to others who have been using it - have you been using it in cold or freezing temperatures? I tend to venture out even more in winter than I do in summer, so have an interest in asking this question!

Thanks.

[LED61]

Well, I can only speak of tropical use here but I bet JS has used it in cold weather!! Now, If you use a set of batteries which have been used even 5 minutes runtime on the MN21, you´ll still get a nice white beam but not the stunningly white that comes about from fresh bats. I´ve got Will Quiles M6-R pack regulated on 7.5V for the MN20 and the MN15 runs not as white and bright as on fresh primaries. So I´m guessing--maybe JS will correct me on this-- that the MN15 on fresh primaries goes at around 7.8V, plus it draws from two stacks. I don´t know but this MN15 beam of fresh primaries goes about as white as I´ve seen an incandescent for a long time. Has anyone used it with a beam difuser ? I wonder what this color and brightness would light up flood with it ?

[js]

OutdoorIdiot,

There's actually a lot to consider when it comes to lamp physics and failure modes of tungsten halogen lamps. We've discussed this a lot in Icebreaks "Race to failure" thread in this forum, and you can read that for further discussion, but I will sum up here:

OK. All the lamps in the SureFires and Tigerlights and MagCharger and SL-20X and etc. are lamps with a tungsten filament, molybdenum pins, so-called "hard" glass envelope (as opposed to quartz glass), and a noble gas fill gas with or without a trace amount of a halogen. The noble gasses are those in column VIII of the periodic table and are highly inert due to the presense of a completed outer shell of 8 electrons. Helium (which has 2 electrons, which is a full shell for 1S orbit), Neon, Argon, Krypton, Xenon, and Radon make up that column. Filling the envelope with one of these gases enabled a leap forward in incandescent technology because it allowed for the suppression of vaporization of the tungsten filament. In a pure vacuum the hot tungsten filament spits out tungsten atoms left and right, which end up coating the inside of the glass envelope, darkening it and reducing the output significantly, ESPECIALLY at the highest possible temperatures. Turn the vacuum into a noble gas like Argon or Krypton or Xenon (Radon is radioactive and is thus a bad choice!) and the pressure of the gas suppresses vaporization (like a pressure cooker raises the boiling point of water). The heavier the atom, the better this works for the same pressure.

OK. So far so good, BUT, this doesn't stop the vaporization; it just slows it down. Enter the HALOGEN CYCLE! Really, a freaking brilliant idea! I read about the guy who pioneered it, but can't remember his name. Anyhow, if you add a little bit of a halogen to the fill gas something wonderful happens. A "halogen" is an element from column VII of the periodic table, such as Fluorine, Chlorine, Bromine, Iodine, or Astatine. Fluorine can not at present be used due to its highly corrosive nature--it attacks the support wires at room temperature and corrodes them. (Too bad, though--if it could be used it would enable an almost endlessly long-lived filament). And I have never heard of Chlorine being used (probably for the same reason). From what I have heard, it's either Bromine or Iodine. (I have no clue about Astatine!).

Anyway, when you add the right amount of some Bromine or Iodine, to the right fill gas at the right pressure in the right size envelope, then something very wonderful happens. The Halogen atoms chemically grab onto the tungsten atoms which have adhered to the glass envelope and remove them from it--thus cleaning the glass. Then, when they wander close to the hot filament, the process reverses and they redeposit the tungsten back onto the filament. Neat, eh? Only small problem is that they don't put it back in the same place it came from, and the thin spots tend to get thinner and the thick spots thicker, until POOF!, you blow your filament at turn on. (Fluorine, as mentioned, would be more egalitarian in this way and would evenly re-distribute the wealth--but, alas, it's too extremist to be utilized. )

So, right, a fill gas is a mixture of gasses like Argon, Krypton, Xenon, (and I think sometimes Nitrogen), and of a bit of gasses like Bromine or Iodine. The exact mixutre of a companies fill gas is a somewhat guarded secret, as are the exact equations and methods behind arriving at the receipe for said fill gas. Besides the exact mixture, you also have the volume (and even shape) of the envelope, filament geometry, envelope material, pin geometry, and (very important) the pressure of the fill gas.

There are a number of trade offs to be made when designing lamps, even if cost is no object. For example, if you up the pressure, you up the efficiency (speaking generally). But, if you up the pressure to the highest levels, you can't have enough of a halogen to balance the halogen cycle because it will start to attack the support pins. SureFire lamps are made so that the halogen cycle just barely doesn't compensate for deposition, and thus the lamps WILL blacken towards the end of their lifespan. However, in compensation for that, they are very efficient due to a higher pressure (and the use of xenon instead of Argon or Krypton).

Now, after that long digression, I will try to answer your question! First of all, as long as no actual water droplets get onto the envelope, and as long as we're not talking direct extreme high velocity cold air exposure, THE COLDER THE BETTER as far as lamp robustness is concerned. In fact, if the air surrounding a lamp starts to get too hot, it raises the internal temperature, including the temperature of the glass envelope. If that goes too far, the glass softens, and POW! the lamp explodes. Not fun. The rule of thumb is that anything below 40 or 50 watts is OK with just regular convective cooling. More than that and you have to start forcing the convection with fans. (Or shorten the runtime! e.g. the USL and "The Torch" and so on = 100 watt halogen lamps, but not run for very long.)

So, the Winter cold will only help with the possibility of an explosion. And, for the record, yes, I have used my M6/MN15 in very cold weather. So cold, in fact, that I got a little bit of condensation on the inside of my lens. LOL! It was for the best, though. Now it's not perfect anymore. It was a replacement for one in which I actually did explode an MN20. That made a friggin mess of the inside I can tell you.

Now, overdrive does increase the temperature which does increase the pressure (which increases efficiency a bit). Yes. But almost always, if everything else is Kosher (i.e. no weakness or fracture in the glass, no finger oil on the glass, etc.) then this will only shorten the life of the lamp. And when it does fail, it will just flash and never turn on again. And if you look, you will see where the filament blew and often a ball of once molten tungsten at the end of one, the other, or both sides:



This was a 62138 100 watt halgoen lamp that I blew with one of the USL packs. It just went FLASH! then nothing.

This is what usually happens. Also, the difference between the pressure of an overdriven and an underdriven lamp isn't that much of a difference. The envelope already has to withstand a good amount of pressure even under normal circumstances. So if there is a flaw or stress or finger oil (bad, bad,bad) then it will blow up whether or not you overdrive it.

Certainly, though, overdriving doesn't help matters! LOL! But, almost all of the time, you can push the lamp right to the point of melting the filament and it won't blow up.

With the MN15, we are in very safe territory by all counts. We are not pushing the lamp very hard, and the size of the envelope vs. the pressure and power parameters are all well and good.

The old MN20, on the other hand, was another story. I estimate that bad boy to be a 19 watt lamp (more or less). But look at the size of the envelope! Small, small, small! The MN15 has the same size envelope as the MN20 even though it is like half the power or something!

Honestly, what I expected SureFire to do with the MN20 redesign was to keep the filament geometry exactly the same, but just enlarge the envelope a little bit and maybe mess with the fill gas or something. But instead, they added two turns to the filament winding, essentially lowering both the CCT and the power and output slightly. Plus, I bet they increased the thickeness of the envelope a little bit.

So, the old MN20's were blowing up due to too high a pressure and too small an envelope, and not so much due to being overdriven. CPFers routinely go way farther in the overdrive department with the Welch Allyn Mag Mods without experiencing as many explosions. Although, the issue is complicated by the PR-base potting done by Carley, and by inappropriate handling of the lamps by novice hotwire guys. To compare apples to apples, we could talk about my TigerLight mods, which use ring-potted lamps (very similar to the SF LA's) and not WA Carely PR-base potted lamps (where one lead must be bent backwards). The Tiger11's and Tiger85's are both driven about two to three times as hard as the old MN20's were driven. (11 or 12 hours of life vs. 35 hours). But as far as I know, none of the production ring-potted WA1111 or WA1185 have ever exploded despite the high level of overdrive. Many people have insta-flashed their Tiger85's, but so far, I know of no one who has exploded one of the production ring-potted lamps. Early on, before I refined the potting process, there was one explosion and one envelope failure, but since then, nada.

Lamp failure is a complicated thing, though, and it's hard to talk completely and authoritatively about it and to interpret something like the rash of old MN20 explosions. But I believe that there was a combination of a flaw in the manufacturing process which tended to produce flaws in the envelopes, together with the very high pressure inside the MN20. I know of no other lamp that has a higher power to volume ratio than the old MN20. For that matter, the new MN20 is still probably the reigning champion of specific power in xenon lamps. Normally lamps that powerful have envelopes the size of the MN21, or TigerLight LA or SL-35X LA. More than twice the volume! Take a look at an SL-35X LA or TL LA lamp and you will see what I mean, and those are 20 watt and 12 watt lamps respectively.

The MN15 is way less power in the same size and does not have a track record of explosions, and it is not being overdriven very much at all. So, I think we are very safe. Still, long term testing is still underway.

But, in short, cold weather is no problem! I took mine out in about 0 F night time weather, (with wind) and other than the slight bit of condensation which happened around the edge of the lens (which left a slight deposit afterwards), there were no problems. And I take mine out in cold weather all the time, although not usually 0 F weather.

Sorry if this post was over-long, but I hope it was helpful. (note that the picture isn't available right now as I post this due to my server being down or something).

[wquiles]

.
(snip)
.
Sorry if this post was over-long, but I hope it was helpful.

As always, great answer Jim - very helpful indeed

Will

[LED61]

+1 I learned tons as usual thanks so much Jim.

[DM51]

Jim, that was a great post - hugely informative. I have learned a lot from it that I didn't know before - you explained it all very clearly indeed.

[SunStar]

-JS-

Thanks for the education. Some of your discussion took me back to my Chem-E reaction engineering courses. I only wish the professors were as proficient in their explanation... (and it was free too!!)

-SunStar-

[seery]

THANKS for the great explanation, always very informative.

I've taken my M6 X-LOLA out several times for night walks when temps were
around zero w/o windchill and (knock...knock) have not yet experienced any
internal moisture issues.

Is it just a matter of time before it happens or were there other factors involved
that caused this to happen on your M6?

Is there anything we can do, as a general rule, to help prevent this from happening?

Last week while poking holes in the ice, I submerged the M6 under the ice/water for
about 30 seconds with no ill effects that I can tell.

Again Thanks Jim.

[OutdoorIdiot]

Hello js,

Thanks for the obvious time and consideration that went into that answer! You've obviously played with and/or researched so many bulbs that you have a very good feel for how much this MN15 is being pushed in this application, so your confidence is rubbing off on me! Mind you, I'm such a dogged empiricist that the fact that you have taken it out in -17 Celsius is the bit that reassures me the most.

I was originally thinking in more simplistic terms of thermal shock, as presumably the MN15 is going to be getting hotter faster than design. But as you suggest, thermal shock was probably not the issue with the old MN20s exploding - in fact now that I think about it, I seem to remember the reports on CPF of exploding ones mentioned that it happened a few minutes into runtime, which coincides with your theory.

Anyway, thanks for putting my mind at rest!

[js]

Everyone,

Thanks for your kind words!

seery,

If you get any volume of air cold enough, the ability of the air to hold moisture will fall below the actual moisture in the air, and at that point you get condensation. So, you either keep the air warm, or ensure that the air has very little moisture in it to begin with. If you're really, really worried about it, you purge with dry Nitrogen! The Fujinon waterproof binoculars are made this way, IIRC.

Anyway, it really isn't an issue at all. There was a little bit of condensation around the edges--the IR through the center was keeping the glass too hot for any condensation to occur near there. But even at its worst it was in no way impairing my beam. It was just a little tiny bit foggy around the rim of the lens for a while. This went away when the light warmed back up once I came inside. But the moisture which condensed there left a barely noticeable residue of minerals or something--not sure. And when I say "barely noticeable" I mean it. I can only see it if I turn on the light and look obtusely at the lens. It's a total non-issue. It's just that before that, the head was absolutely perfect. No spec of dust, no hair, nothing. It was as clean and perfect a flashlight lens as I have ever seen.

So I noticed when it fell off from that level of perfection. But honestly, it was for the best. Plus, that hadn't happened before on just normally cold winter weather walks. It didn't happen at 10-30 F, for example. But that particular night was freaking COLD!

Around here, we all tend to get too attached to the aesthetic perfection of our lights. Sometimes even to the point of making them shelf queens; even to the point of not using them when we otherwise might want or need to.

Or worse, someone will try to open up his SureFire bezel to try to remove a hair or spec of dust, and go from bad to worse, damaging the light, or mucking up the lens or something.

I know it's hard to treat a $400 light as if it were a tool of sheer functionality and practicality, rough and ready and tough and durable. Able to take abuse and keep on working. But, that's what the M6 is! Granted, I don't intentionally scratch my light or try to "break it in" by going above and beyond my normal use and needs. I think that's going too far the other way. But, I do try to make myself use my lights, even my perfect ones, and if they get scratched, or if the lens gets a wee bit of condensation on it, so be it! It's par for the course. And no one else but me would probably realize that the lens of my M6 head wasn't perfect anyway.

As for submerging the light in ice water, no, I don't think that's a no-no. The lens is optically coated pyrex glass! That's the stuff that will take the direct flame from a bunsen burner, isn't it? I think you're safe as long as you don't submerge just half the lens and leave it running that way. Just make sure not to put such differential stress across a definite area. It probably wouldn't take that. But, a quick change from hot to cold over all or part of the lens will be fine. I mean, I wouldn't do it just for kicks, but if I actually needed to run my M6 under ice water, I'd do it.

Plus, hey, if it does crack, SF would probably warrantee it. That's what the M6 is. A special operations light for extreme use. It's expensive for a reason. If it fails, take advantage of the SF warrantee! "If it breaks, we fix it." Isn't that what they say? (excepting lamps and switches wearing out with time and use, of course).

[Schnotts]

Now I want an M6

[wmugrad28]

Hi js,

HOLA: MN21. 630 lumens, 20 minutes.
LOLA: MN20. 400 lumens, 1 hour.
X-LOLA: MN15. 200 lumens, 2.5 hours.

Is the 400 lumens estimate for the LOLA using the new MN20 lamp? If not, do you have an estimate for the new number of lumens?

[zehnmm]

First, thanks especially to JS and others for the informative posts about the M6+MN15 solution.

Question: after searching and reading the posts regarding AW's new protected R123A's, has anybody tried this in the 3s2p MB20 holder on the 3 lamps (MN20, MN21, and MN15?) Runtimes? Thoughts?

I apologize if this has already been addressed in other posts and I did not search enough.

Thanks!

[LED61]

Do not try this setup. The added voltage of the three in series R123's will blow the 9V lamps for certain. There is a chance however this setup may work with the MN60 and MN61 12V lamps. Nothing is for sure yet and can not be recommended. I imagine JS will hop in any minute with more info but this is in another thread.

[zehnmm]

LED61: Thanks for the info. You know, to be perfectly honest, I had forgotten about the nominal 9V of 3x CR123's versus something like 10.8 - 12.0 for 3xRCR123's.

Do you think 2 dummies could be used in the holder so that you have 2x RCR123's in each of the 2 series in parallel?

Thanks!

[LED61]

Hmm, I think JS is better qualified for this question BUT, I will venture to say that you can do it only on the lower current draw lamps or possibly only the MN15. The voltage sounds fine provided you can find the correct slots for the dummies in the MB20 but the current draw will be too high for only two cells in series if you use the MN20 or MN21. Plus, you will not have the extended runtime, which is the real beauty of the X-LOLA on primaries.

[zehnmm]

Thanks LED61!

[cnjl3]

JS,

Just wanted to say ‘Thanks’ for all your info on a great new bulb.
The MN15 kicks butt!
Prior to the MN15 I was only using my M6 during hunting season with the LOLA.
I pretty much stayed away from the HOLA due to the 20min run limit.
Hunting season ended first weekend in Jan 2007 and during the last month of hunting season I used the MN15 on mostly every trip and I really, really like the beam.
Yeah, it doesn’t have the output of the LOLA but it is more than enough white light for me. Plus, now instead of putting my M6 away in my gun safe for next years hunting season it sits next to my Surefire A2 at the ready for night time explorations.

[js]

wmugrad28,

I do have both new and old MN20's and I have done a very little bit of testing with the new MN20, but I am not prepared to say much at this point regarding the comparison of old to new, other than that the new is a lower CCT and lower output, BUT NOT BY MUCH. There will be more on this from me later, and I will post a link in this thread if you like. But right now, that's all I will say.

zehnmn,

As LED61 points out, using R123A's in place of primary 123A's will blow the MN21, MN20, and MN15 lamps, whose voltages, respectively, are about 6.8, 7.5, 7.6.

Adding two dummy cells would definitely be OK with the MN20 or MN15, but the current draw of the MN21 is too much for only two stacks of R123's (2.5 amps per stack!)

And in all cases, we are talking about using Li-ion cells. Obviously, AW protected cells would be best for safety's sake, but we (meaning SilverFox) are still testing them. Hold tight.

Check out this thread: another M6-R with MN61 although be advised right now that I am more in favor of the MN60 instead of the MN61. But I say this in the thread, as you will see.

cnjl3,

Nice! Thanks for posting that! It's a great example of my own assessment of the situation. The MN15 isn't nearly as much light as the MN21 or MN20, but it's nice and white, and often, it's very much enough light to do the job and do the job well. Add to that the 2.5 hour runtime, and convenience of primaries, and a beautiful, lovely beam, and the ruggedness and ergonomics of the M6, and you've got yerself a winning combination. (In my opinion).

[seery]

The M6-X has to be hands down the most rugged and versatile light I've
ever had the pleasure of owning/using.

Wish there were a CPF medal of honor we could award you for sharing with
us your M6-X creation.

OK beer is on me at SHOT 2008. Oops did I just say that out loud!!

Beacuse my M6's are used nearly every day, the SF 123 cells are bought in
full 400 count cases. Thanks to the M6-X, the past few months these cases
seem to dissapear at a much slower rate.

Just lately sold the last of my SF 9N's I've had for 12-13+ years. Only reason
was I came to hate rechargeables in my "go to" lights.

Seems every time I'd "go to" they'd "go dead"!!!

The MN15 isn't nearly as much light as the MN21 or MN20, but it's nice and white, and often, it's very much enough light to do the job and do the job well. Add to that the 2.5 hour runtime, and convenience of primaries, and a beautiful, lovely beam, and the ruggedness and ergonomics of the M6, and you've got yerself a winning combination. (In my opinion).

[zehnmm]

JS: Thanks for sharing this absolutely fascinating information. I had somehow or another missed the other posts and appreciate the opportunity to read them.

For me, while I do not have an M6, this whole topic is intoxicating. JS: I am especially fascinated by a comment that I believe you made in one of your posts about the 6xCR123's running the MN15 for something like 2 1/2 hours. As I recall, the comments included something like about not having to change batteries as often with this setup when you get 2 1/2 hrs. runtime. (If I have misunderstood your point, I most certainly apologize.) Having said that, I got to thinking some more about this. I find the following example comparison helps to amplify JS's comments about the 6 x123's.
In the comparison, I compare my WE 100x (running 12V bulb, 300 bulb lumens, 195 est. torch lumens) and the M6+MN15+6x123's.

.
...............Est................................ ........Battery...Battery
.............Torch....Hrs......Lumen...Battery.. Cost......Cost/
Light.....Lumens..Runtime.. Hours..Cost...... Per Hr... Lum. Hr.

M6 ........200....... 2.50...500.0....$6.60....$2.64....$0.01
WE100x...195........0.83...162.5....$4.40....$5.28 ... $0.03

In this comparison, I assumed that one would use Battery Station 123's that you can get for $1.10 each from Lighthound in quantities of 10 or more. (If SFs are assumed the costs change accordingly....) Moreover, I introduce what I am labeling "lumen hours" --- which is simply the est. torch lumens times the runtime. In other words, it is an artificial quantification that takes into account how long two similarly bright bulbs will run. The M6 battery cost is more. But now, if you compute the battery cost per hour, the M6 costs exactly one-half that of the WE 100x for close to the same torch output. Moreover, the M6, using the MN15 bulb, runs about 3 times longer. When the battery cost per "lumen hour" is computed, the M6 solution is one-third the cost., which, in this case, factors in the 3x runtime differential.

Hence:
1. At first glance an expensive M6 light ($350 - $370) with 6 batteries appears to be an unworthy choice.
2. But when compared to one example of another choice (WE 100X,cost of $90), the longer runtime for the same output really starts to shine. The total cost of ownership over several years in comparing the M6 with another choice begins to narrow quite a bit.
3. Plus, you get a great light.
4. Additionally, there are some re-chargeable options that have been discussed.

Please do not get me wrong about the Wolf-Eyes light. I think it is an absolutely great light. I really like mine and when hunting, tracking game, etc., it is in my hand. Throws great. All I am doing is extolling the virtues of the M6 option that JS and others have described.

The big problem with all this is now I have to scrounge some money up and buy an M6!!! Then I have to buy some more lamps, perhaps another FM battery holder (to go with the 3 that I already have of his,) perhaps get his socket for the M6, and who knows what else.

Oh, the pitfalls of being a CPF-er! Oh, the humanity!

Thanks to you all.

Regards.

[js]

seery,

WOW! Thanks so much! That's high praise indeed!

I agree about the rechargeables thing. Mostly in regards to NiMH, but not exclusively. There's something really cool about being able to carry 6 or 12 extra 123's with you, knowing you have access to another 2.5 or 5 hours of light. The SF Spares Carrier would also house another MN15, should the one in your light burn out. I've said it before and I'll say it again: I love rechargeable lights (such as my TigerLight) and I understand the advantages to them, but if it ever REALLY mattered, I'd chose my SF M6 loaded with primaries, MN15 or MN20, and extra batteries.

zehnmm,

Fascinating! I love the comparison. I don't know too much about the WE light you compare to, though, but I get your point, and yes, it was the same one I was making before about the greater efficiency, greater energy extraction from the 123's when drawing out at this slower rate (as opposed to 1 hr or 20 min runtime rate).

[kaseri]

After reading this thread I decided to order my own MN15 lamp. I love my M6 but now I'm thinking that I will love it even more.