Surefire Bulb Use Question** MN20 in a M4 and M6

[ConfederateScott]

I am aware that the MN20 is the LOLA for the Surefire M6 and not for an M4. But I swap my turbohead from my M6 to my M4 on occasion and I was wondering if the MN20 lamp assembly would work just as well in the M4. It lights up and is pretty freakin bright but I was just wondering about the 4-cell versus 6-cell difference. Will it burn the assembly out sooner or just drain the cells quicker? Anyone have any answers or experience doing this? I prefer my KL6 on the M4 for most needs but occasionally I want the throw of the incandescent.

 

[Topper]

Sounds bad to me. The M4 is 12volt The M6 is 9volt even though it has 6 cells so shoving 12 volts through a 9volt lamp sounds way overdriven and will flash the lamp I guess if you are using 2 168s pilas in the M4 it might work allright, I have not tried that.
Topper /ubbthreads/images/graemlins/smile.gif

 

[ConfederateScott]

Yep, you're right as rain. I decided to sit here and play around with it and see what would happen. I began shining around the M4 with the MN20 in it. Using a brand new set of Golston Cr123's. Well after less than a full minute of intermittent use the MN20 stopped working. I put the KL6 back on the M4 and it fired up. So I then put the MN20, still in the turbohead on the M6. It started working again like a charm. Go figuer. I thought I had blown the lamp when it stopped working in the M4. But apparently not. Now I know the answer to my question though. It's a bad idea. Thanks

 

[js]

Constable,

What happened is that you activated the thermal shutdown on the batteries in your M4. The MN20 draws around 2.5 amps in the M6. This is only 1.25 amps per stack of three 123's. Now put it in the M4 and you are providing more voltage (probably) and thus the MN20 will ask for MORE current, and 2.5 amps is just about the maximum current draw you can get from a single stack of 123's. Thus your 123's got so hot that they cut out (which is one of their internal protection features).

Let me say right now: You are lucky. This could have ended differently. You could have EXPLODED the MN20 in your Millenium Turbo head and ruined the lens and reflector as well as the lamp. A cool $150 or so down the tubes.

Be very, very careful about swapping lamps from light to light. A "9 volt" SureFire light is NOT really supplying 9 volts. The batteries sag under load. The greater the load the greater the sag. People often try installing an MN16 M3T HOLA in their M6, thinking "they're both 9 volt lights, so this should work." *buzzer* Not so. The M6 is running TWO stacks of three 123's and will thus hold a HIGHER voltage under load, and will blow (best case) the MN16 or explode it (worst case).

SureFire lamps are carefully matched to their power sources and caution is advised when trying non-standard configurations.