2X IMR 18500 + MN21 = SUCCESS!!!

[Outdoors Fanatic]

What's up, my fellow Incandescent lovers!


I am immensely happy to report you, that according to my 'un-scientific' tests, it is safe to run the MN21 on IMR cells as long as you don't go higher than size 18500. No instaflash so far--even on topped-hot-off-the charger cells (I've repeated this test countless times on healthy IMR cells).


Apparently, the voltage sag is enough to prevent a dangerous overdriving (either that, or my MN21 is one tough SOB). Eventhough there is some voltage sagging, it is noticeably brighter and whiter than either on primaries or on 2x AW18650 LiCo cells.
Not to mention and it delivers a very flat discharge curve. What a great setup! This makes a great Winter "Pocket Rocket". 2x18500 form-factor and the KT2 is compact enough for any cold weather jacket. Brighter, lighter and much more compact than a Mag ROP 2C, you can't go wrong with this setup.


Cheers.
lovecpf

 

[Dioni]

Great news!
I'm happy with your report. Congrats for your "winter pocket rocket"!
It is really a bright setup :devil:

Cheers,
Dioni

 

[Steve in SoCal]

I am currently running a MN21 on 2 x IMR18650 (fully charged) in my M6 and its work great. Runtime stinks though. I do use an AW softstart so that helps not to blowup the bulb.

 

[ShineOnYouCrazyDiamond]

Just as an FYI warning - I had been running a MN21 on 2xAW-IMR26500 with no problems for about a week or so. But, it was only in short 30-60 second bursts with AW softstart.

One night I was showing off the light a bit and let it run for about 5-10 minutes until there was a terrible sound of cracking glass and the light went out. The MN21 bulb had literally exploded in my KT4 head - any as you may be guessing - $195 straight down the drain as the glass shredded parts of the reflector and coated the whole thing internally in white powder.

Just my unfortunate experience. WA1111 still a safer alternative.

 

[Outdoors Fanatic]

ShineOnYouCrazyDiamond;

The 26500 is way too much even in plain LiCo chemistry, so the IMR version is just insane.

 

[ShineOnYouCrazyDiamond]

Well I'm glad it at least happened in a replacable head and not my FM3X which was hard to find.

I am still just saying that for the risk associated with running the MN21 on IMR cells there are safer better alternatives.

 

[Outdoors Fanatic]

I guess the only safe way is in the stock SureFire M6 loaded with primaries. Even on 2x18650 LiCo you're risking it. But I'm not too worried over a few lost hours of lamp life...

 

[RobertM]

What's up, my fellow Incandescent lovers!


I am immensely happy to report you, that according to my 'un-scientific' tests, it is safe to run the MN21 on IMR cells as long as you don't go higher than size 18500. No instaflash so far--even on topped-hot-off-the charger cells (I've repeated this test countless times on healthy IMR cells).


Apparently, the voltage sag is enough to prevent a dangerous overdriving (either that, or my MN21 is one tough SOB). Eventhough there is some voltage sagging, it is noticeably brighter and whiter than either on primaries or on 2x AW18650 LiCo cells.
Not to mention and it delivers a very flat discharge curve. What a great setup! This makes a great Winter "Pocket Rocket". 2x18500 form-factor and the KT2 is compact enough for any cold weather jacket. Brighter, lighter and much more compact than a Mag ROP 2C, you can't go wrong with this setup.


Cheers.
lovecpf

Interesting...how much current are you measuring at the tailcap?

 

[ShineOnYouCrazyDiamond]

Hey - Outdoors Fanatic - what is the longest time you ran this lamp for?

I just ran a MN21 with IMR18500 along with an AW softstart, this time in a KT2 head with a FM 2x18500. After running for about 7-8 minutes the head shattered on me and has pretty much ruined the KT2 head.

I think the problem is that the IMR cells hold too much voltage even under 5 or 6 C loads.

Be careful with your setup!

 

[Steve in SoCal]

So does that mean you have ruined two turboheads? That definitely sucks and should be a warning to others (including myself) that running 2x IMR with the MN21 is dangerous beyond a few minutes.

 

[Dioni]

Hey - Outdoors Fanatic - what is the longest time you ran this lamp for?

I just ran a MN21 with IMR18500 along with an AW softstart, this time in a KT2 head with a FM 2x18500. After running for about 7-8 minutes the head shattered on me and has pretty much ruined the KT2 head.

I think the problem is that the IMR cells hold too much voltage even under 5 or 6 C loads.

Be careful with your setup!

that is definitely a dangerous setup!

 

[ShineOnYouCrazyDiamond]

Yeah - One KT4 and one KT2. The KT4 is destroyed internally :mecry:, I am working on slowly cleaning the KT2 - it may be partially salvageable w/ only a few nicks when done.

It's one heck of a great beam - but I think I will stick with either the WA1111 or IMR-M3T for my 2-cell bright beams.

 

[Steve in SoCal]

:whoopin:

Maybe you could use the old KT4 head for a LED ZEP mega output upgrade?:twothumbs

 

[Outdoors Fanatic]

Hey - Outdoors Fanatic - what is the longest time you ran this lamp for?

I just ran a MN21 with IMR18500 along with an AW softstart, this time in a KT2 head with a FM 2x18500. After running for about 7-8 minutes the head shattered on me and has pretty much ruined the KT2 head.

I think the problem is that the IMR cells hold too much voltage even under 5 or 6 C loads.

Be careful with your setup!

Damn, you're one truly unlucky flashaholic! I'd HATE to lose a KT2... How many hours or how old was your MN21? Mine is brand new and I've burn it for an hour or so tops (8 minutes continuos). No problems so far but your bad luck did make me extremely nervous right now. I'm very sorry to hear that you lost another SF turbohead... I guess no lamp assembly is 100% equal and there are many other factors at play.

 

[Outdoors Fanatic]

Interesting...how much current are you measuring at the tailcap?

I'll have to check it out...

 

[Dioni]

Could the winter season have contributed to this result?

 

[fivemega]

:rock: 2X IMR 18500 + MN21 = SUCCESS!!!

Or maybe

:thumbsdow 2X IMR 18500 + MN21 = :mecry:

I know eventually you will do it but don't test in expensive turbo head.

This set up is on very edge of border line. Slightly invisible contact corrosion or excessive resistance may push you to other side of border just like OP and save your bulb for few hours. Not to mention, batteries, charger, ambient temperature and... will make some changes from this side of line to other side.

 

[Outdoors Fanatic]

:rock: 2X IMR 18500 + MN21 = SUCCESS!!!

Or maybe

:thumbsdow 2X IMR 18500 + MN21 = :mecry:

I know eventually you will do it but don't test in expensive turbo head.

This set up is on very edge of border line. Slightly invisible contact corrosion or excessive resistance may push you to other side of border just like OP and save your bulb for few hours. Not to mention, batteries, charger, ambient temperature and... will make some changes from this side of line to other side.

Please, recommend a safer alternative with similar output.

Cheers.

 

[fivemega]

Please, recommend a safer alternative with similar output.

Cheers.

Safer alternative is 2 protected 18650 or 2x25530 with WA1111
Similar (or better) output is 3x17670 with WA1185
There are lots of beamshots and usefull information here and here.