MN21 in M4????

[DaFABRICATA]

I bought a M982XM07 Weaponlight a while back, same as M4.

Anyway the guy that sent it to me had an MN21 in it!!
I din't know for a few weeks and thought the light was VERY BRIGHT AND WHITE!!!
I'm surprised it didn't insta-flash....is it possible to run this set-up??? or did I just get a tough bulb?

Any help would be great:wave:

 

[nzgunnie]

That is intersting, perhaps the current draw is sufficiently high that the voltage delivered to the bulb is low enough not to instaflash it?

 

[Size15's]

I saw an MN21 in an M4 once but the output was dreadfully dim and yellow - it was one of the reasons why I checked the M4 and immediately saw that the bulb wasn't an MN60/MN61 because the bulbs are different to the MN20/MN21.
I was also surprised that it didn't explode but chalked it up to SureFire making robust and resilient lamps.

Al

 

[ampdude]

Yea, I would think a couple factors would be in play here.

1. As mentioned the high current draw of the bulb drops the voltage of the four CR123A cells under load significantly.

2. The M6 is 3 cells in parallel with 3 other cells, so the voltage drop across the 9V lamp will be higher than a normal three cell CR123A 9V lamp. So it's probably more robust than the typical 9V lamp assembly.

The guy that originally did this might be onto something!!!

 

[mdocod]

runtime will be about 5 minutes on a MN21, if you run it for any more than a few seconds at a time you risk overheating and tripping the PTC in the cells. If the cells hold their voltage any reasonable amount under that load then you may be at a higher risk of instaflashing it. Stick to the MN61 for high output, The MN21 on 4 primaries just isn't a good idea for a lot of reasons, the main one being that it is dangerous (big chance of cell explosions), and is a huge waste of potential energy in CR123s.

 

[DaFABRICATA]

I didn't plan on running this set-up but I was really impressed with just how crazy bright it was! I will stick to the correct bulbs, but I wanted to bring this up to see what others had to say.

 

[js]

There is a mod that some have done where they drill out the body of an M4 and use two 18650's to drive an MN21. Never done it myself. But driving an MN21 on four CR123A's is NOT--I repeat--NOT advisable. Also be careful using Li-ion 18650's if you go that route.