Your thoughts on the Surefire M3-CB...

[Strauss]

Hello everyone, I just was lucky enough to pick myself up a brand new Surefire M3-CB I really love the look and feel of this light, it is perfectly balanced in hand. I plan on USING this light, so I purchased the V71 holster for it and am carrying it bezel-up in it...so I scratch the tail-cap and not the bezel.

I am running a pair of 17500's in it with the MN10. In my makeshift light-box, I am getting ~165 lumens out the front on fresh cells. Like others have previously noted, the MN11 requires a "double-click" to power the lamp. Although the 17500's are too small to supply the proper current demands for the MN11, the light is still much brighter with the 17500's than with primaries. I am aware that it is not safe for the batteries, which is why I plan on running the MN10 with the 17500's. I was just stating the results that I obtained. With primaries and the MN11, I was seeing ~250 lumens out the front, and on 17500's it jumped up to ~350.

What impressed me the most was when I added the cell extender and 2x17670's. With the MN11, output increased to ~425 lumens out the front on fresh cells! This was a great set-up, but like a few others have noted, I don't want the extra length since I plan on holstering the light daily(and nightly :naughty: ). Looks like my only option is to wait for the LF M-series bulbs to come out. Their high output lamp's current draw will be within the 17500's limit, so it looks like thats what I will have to go with if I don't want to lengthen the light.

I figured we could use this thread for owners of the M3-CB to chime in on, and talk about their set-ups and opinions of this beautiful light. So for all you M3 owners out there...show yourself!

 

[defusion]

I own one, love it! running it one 17500's with the MN10 aswell
I can't wait for those LF bulbs to come out either! I love the MN11 on 17500's, but i don't really like the double-tapping, so i simply want the highest possible output i can get from 2x17500's and standard bezel.

One question though:
How did you measure the light output? it seems a bit ...unrealistic

 

[Strauss]

I measured the output with my home-made lightbox and extech meter. It's no integrating sphere, but it's suprisingly accurate. I would say it is within +/-10% of the actual numbers.

Surefire's lumen figures are underrated. They take an average of the lumens during the runtime, not peak numbers on fresh cells(like I did). Also, when driven on lithium-ion's, Surefire LA's are known to put out more output than with primaries. The lumen figures I stated are "peak" numbers, with fresh cells at ~4.2V. Those figures drop during the burn-time. For example, the MN16 in my turbohead starts out ~425 lumens, but after about 5min it's output already drops to the ~350 lumen area. At 15min, it's down around 300-325 lumens and keeps dropping till the cell protection kicks in around 30min(2x17670's).

 

[mdocod]

your numbers suggest ~33 bulb lumens per watt. that's pretty optimistic, then again, on FRESH cells, these lamps are pretty impressive, idunno. I estimate the MN11 on 2x17670s to be 270-360 torch lumens on cells in the "fresh" region.

 

[trouble]

I've had a M3 since 00 I've carried it on duty and for a while was my only SF. I run 123's in mine with the HOLA and it's brightness has saved my bacon a few times on duty, SF's ads aren't just hype this much light in dark adapted eyes really has a telling effect. I can think of 3 times this light has kept me from having to "lay hands" on a suspect. Mine doesn't get as used as my TH's which run on rechargeables, but I'd gladly pick it up and use it on duty if needed. M3's are great lights IMO.

 

[jimjones3630]

Me too, for the M3 with 2x1750 and HO LF replacement.

 

[Strauss]

Thanks for the comments everyone, now lets keep 'em coming! I know there are more M3 owners out there!

 

[mdocod]

so I was playing around with re-rating formulas, and tossing some numbers around on paper...

Here's what I came up with:
a P91/MN11/MN16, is a bulb with a design of 6.75V, ~2.5A, ~50 hour life, ~3250K, ~17W, ~375 bulb lumens, ~22.5L/W, or 244 torch lumens. This works with your "250 lumen" results on primaries.

a P91/MN11/MN16, driven by a FRESHly charged QUALITY pair of Li-Ions, runs about 7.8V, ~2.7A, ~3400K, ~21W, ~600 bulb lumens, 28.5L/W, ~400 torch lumens.

here's how I figured this..

If you look at the charts for Li-Ion cells, you see that AWs 17500 cells, can deliver about 3.8V when FRESH into the 2.7A load of a P91 at this level. That's 7.6V instead of the "designed" 6.75V. If you apply the halogen re-rate formulas, (which should be in the ballpark for a xenon lamp) , you get 568 bulb lumens, which translates to 370 torch lumens. which agrees with your observations, The 17670s probably pushed it up around 7.85V at the bulb for the first few seconds, which would account for your measured 420 torch lumens. At this drive level, the adjusted bulb life is about 8 hours, which should be pretty safe considering, it only sees that level for short bursts, quickly diminishing to more appropriate drive levels.

So... after reviewing in more detail, I guess your results may be very valid. that's pretty cool.

 

[Strauss]

So... after reviewing in more detail, I guess your results may be very valid. that's pretty cool.

Thanks for the technical analysis! For some apparent reason, my lightbox is very accurate. I don't consider my results 100%, but I am willing to back up my claim of within +/-10%. I used my old HDS, which I assumed was 60 lumens, to set-up my calculations in the box. I know it's no integrating sphere...but it works damn good for a $120 lightmeter attached to a 1gal. orange juice jug

 

[emitdab]

I love my M3 it is what got me into this craziness (others view) of high dollar flashlights. I was once in a dangerous situation and had a light fail (won't say brand). Next week ordered a M3. Never a worry since. And a few funny (I think) stories.

 

[Patriot]

I really like mine and carry it when I want something more serious than an L2 or L4. It's still pocketable unlike the M6 and I run it conventionally with HOLA on primaries.