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Posted: 8/28/2004 8:57:07 PM EDT
For some of Surefire's flashlights, you get a standard output lamp that burns for 60 mins and there is available a high output lamp, but only runs for 20 mins. My question is: Due to the extra heat generated, can you run the high output lamp for 20 minutes continously? If not, what is the longest time spanse that you can run it before you melt something?

Thank you very much!
Glendale, AZ

Link Posted: 8/28/2004 10:18:08 PM EDT
[Last Edit: 8/28/2004 10:21:53 PM EDT by kenjgood]
With a lexan lens, you will be melting is a couple of minutes. Couldn't tell you exactly when. The higher output lamps are best used in intermittent mode with lexan.

Even the standard 6-volt P60 or 9-volt P90 will melt your lens if the light is activated in Constant ON when stored in a bag. Hence the development of the "lock-out" tailcaps.

Folks were getting tired of pulling out their MP-5s to find dead batteries and a melted lens.

Pyrex (glass) lens, no problem.

Keep in mind, the 20 minutes runtime is not 20 minutes at X lumens. It is 20 minutes of total runtime. The curve immediately peaks over the rated lumens for the first few minutesof the cycle, then starts tampering off from there unless the light is digitally regulated.

From what I can tell, Lithium batteries like the heat in the sense they really put out when above normal carrying temps.

If they get too hot, they have a built in "fuse" if you will - Thermal Shut Down. When they get back below acceptable operating temperatures, then your light can be activaged again.

The only lights that I ever experienced this shutdown was with the older 12PM/ZM's or its replacement the M4 Devastaor. These lights (500 Lumens with the NM62 lamp assembly) had 4 batteries in series and really heated up!.
Link Posted: 8/28/2004 11:19:02 PM EDT
If you use the G2 or G2Z, the heat is very concentrated at the bezel because Nitrolon doesn't conduct heat as well as Aluminium. Some people have experienced Thermal Shutdown using the P61 in the G2/G2Z.

I've only experienced Thermal Shutdown using the N62 lamp like Ken in the 12PM or M4. This usually happens after about 2-3 minutes.

I guess that for WeaponLights the weapon could sometimes be very hot too. I guess that this means training is vital to ensure that your setup works as you intend it to. If this means your bezel is getting damaged then perhaps getting one of the Pyrex lens bezels is the answer, or moving to a metal light that has Pyrex as standard.

Link Posted: 8/28/2004 11:33:47 PM EDT
During a fairly long period recently (posted on the attic while the rest of the guys did primary and secondary clearance), I noticed that the grip on my M900 got pretty darned hot, even through Nomex gloves. Figure about 10 minutes. I had a similar experience recently covering an entry point on a building that we suspected still cntained a burglar. I usually do not leave the light constatntly running, but sometimes it is called for by the tactical situation, and those batteries can get hot.

I have also swapped many folks melted lenses for new(er) bezels when they left their SF "classic" lights fully up in the bag for two long. The solution for this is to unscrew the end cap just enough that the tape switch won't activate before putting the weapon away in your trunk.

In LE circles, there is a picture and a warning about a fellow from a state agency in the South circulating. It shows a light (I don't think it was an SF, though), left in a raid bag that caused a rather spectacular meltdown, fusing to a pistol (Glock, I think) magazine that was also right next to a bang. Luckily for those involved, there were no secondaries. Make no mistake, these things do get rather hot.
Link Posted: 8/28/2004 11:54:26 PM EDT
Well it took me 12-15 minutes to find out that if I let my Z3 on with the high output bulb (200 lumens) it will melt the glass. It was my first SF, I was changing the battery of one of my watches and I droped one of those tiny screws into the carpet... I never found the screw and of course the glass of of my Z3 was all deformed and melted. The good news is that when I called SF they didn't even let me finish explaining what happened before they ask for my address... 4 days later I received the replacement lens for free. Certainly SF has the best customer service that I have experineced!!! I wish all companies will have the same ethics...
Link Posted: 8/29/2004 9:00:04 AM EDT
The Z3 was never released with a glass lens that I'm aware of. The Z3 was discontinued before the standard bezel was switched from its Lexan (polycarbonate) lens to the tempered Pyrex (glass) lens that the Z2, 6P and others enjoy today.
The maximum short term temperature for Pyrex is about 500C and that is before it starts to go soft.
If SureFire sent you a replacement lens it was the Lexan lens kit (Z17).
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