# Redux: Mag 2C running 3x CR123A



## ElectronGuru (Jul 14, 2009)

One of my favorite Maglite upgrades is also one of the oldest and one of the easiest. Given to me (literally) by Niteowl shortly after my arrival on CPF, this venerable mod seems to have new uses every time I turn around. Here is a primer on the basics of the setup, followed by two cool examples, one *LED* and one *incan*.


Here is the complete before and after. Start with a Maglite 2C and 1) replace both C batteries with three CR123As (or IMR16340's), 2) shorten the spring, and 3) add a tube wrapped in a pair of gaskets.







The result is more voltage (3 -> 9 (10+ with IMRs)) and less weight (and capacity)






First get the right tube and gaskets. This one is 7/8" (outside diameter), cut to 4" long, with gaskets just tight and thick enough to hold the tube in place.






Everything stays centered and snug, without being difficult to remove. When they're thick enough, the gaskets have a tendency to roll down when inserted, so role them toward the top before installation.






Then comes the tricky part, shortening the spring. New ones are cheap, so messing up isn't a big deal. Its also very easy to convert a light back and forth and move the mod parts between different lights. Bolt cutter your way through or get two pairs of pliers. Put them on either side of the breaking point, then bend back and forth until the pot metal gives up and seperates. Leave about 2/1/2 turns and then center the last half turn so it makes broad contact across the smaller (-) on the new cells.






Then you're ready to load er up. Here's a fun incan configuration (incan-tation?). 3xIMR16340 + Fivemega bipin adaptor + WA1331 bulb. Result: about 800-900 lumens of near white color (vs 200-300 for the original 2003 version). This just in, 1331 bulbs are marked for death.






Here's a fun LED config. An exotic TerraLUX (if there can be such a thing) that normally requires longer/heavier Mags to function.














:devil:​


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## Kestrel (Jul 14, 2009)

A good primer with really nice photos. Thanks,


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## jaundice (Jul 15, 2009)

Electronguru;

What's the ID of the tube? Also, exactly what sort of tube are you using? It looks like some sort of poly tubing? I've tried this with some heater hose, but it was too thick. I also tried some plastic tubing, but it I had trouble with it binding on the inside of my flashlight.

Thanks,

-John


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## jaundice (Jul 15, 2009)

Also, any tips on how to do this for a D cell mag?

Thanks,

-John


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## elumen8 (Jul 15, 2009)

Thanks for bringing back good memories. My very first mod of any sort was the Mag 2C loaded with three CR123s and a 5-cell Magnum Star Xenon bulb. Just a simple little mod, not the brightest in the bunch, but it got me started.

JB

btw..it wasnt even that long ago


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## supasizefries (Jul 15, 2009)

Very very cool. I recently just bought a 2C to start modding it. I've got a couple of 2D builds under my belt but I absolutely love the 2C form factor.


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## Niteowl (Jul 15, 2009)

jaundice said:


> Electronguru;
> 
> What's the ID of the tube? Also, exactly what sort of tube are you using? It looks like some sort of poly tubing? I've tried this with some heater hose, but it was too thick. I also tried some plastic tubing, but it I had trouble with it binding on the inside of my flashlight.
> 
> ...



The tubing is a flexible, polymer pipe Sold as "Flex-Pex" where I bought it. It's used for plumbing in place of rigid pipe. A straight five foot section was about $5. 

The ID is roughly 16.5mm or 21/32" (just over 5/8"). OD is roughly 22mm or 7/8".

Nice tutorial on a quick and easy mod sure to bring a smile to the face to those trying it for the first time. And as ElectronGuru shows, it also has uses for those deeper into the hobby.


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## Justin Case (Jul 15, 2009)

jaundice said:


> Also, any tips on how to do this for a D cell mag?
> 
> Thanks,
> 
> -John



Here are two approaches that I've found:

https://www.candlepowerforums.com/posts/2781120&postcount=6
https://www.candlepowerforums.com/posts/2812671&postcount=35

https://www.candlepowerforums.com/posts/2781182&postcount=8


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## jaundice (Jul 15, 2009)

Niteowl said:


> The tubing is a flexible, polymer pipe Sold as "Flex-Pex" where I bought it. It's used for plumbing in place of rigid pipe. A straight five foot section was about $5.
> 
> The ID is roughly 16.5mm or 21/32" (just over 5/8"). OD is roughly 22mm or 7/8".
> 
> Nice tutorial on a quick and easy mod sure to bring a smile to the face to those trying it for the first time. And as ElectronGuru shows, it also has uses for those deeper into the hobby.


 
Interesting. My intention was to use 18650s, which, of course, are wider than 16340s. It looks like this mod is geared specifically to 16340s. Perhaps that's my problem.

-John


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## ElectronGuru (Jul 15, 2009)

Niteowl said:


> The tubing is a flexible, polymer pipe Sold as "Flex-Pex" where I bought it. It's used for plumbing in place of rigid pipe. A straight five foot section was about $5.



Thanks for chiming in! :thumbsup:





jaundice said:


> My intention was to use 18650s, which, of course, are wider than 16340s. It looks like this mod is geared specifically to 16340s. Perhaps that's my problem.



Yes and no. The basic principal here is to use a tube + gaskets to reduce the diameter of the battery tube. Without the gaskets, the OD has to precisely fit and even if it does, its a pain to remove. This "new" approach can be scaled as far as parts can be found or made to make it work. Bring your light and batteries to the nearest home center and experiment. Find a tube with an ID that works for the cells but still giggles around in the light. Then find gaskets to hold the tube steady inside the light.

But keep in mind that 18650's are longer (30mm for two), so you'll need to modify the tailcap more. Here's an elegant solution (click the photo to see more):




​


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## Justin Case (Jul 15, 2009)

This thread shows another make-shift sleeve made from readily-available materials to fit 18650s in a C Mag. Use Orbit 1/2" x 24" Flexible PVC Pipe available at Home Depot hardware stores.

If you combine this with FiveMega's Wide/Deep Tailcap, you should be all set to run a 2C Mag using 2x18650.


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## supasizefries (Jul 15, 2009)

Electron Guru: I'm assuming the tail has been de-anodized and the spring has been cut to fit 2 18650's? If so, I'm all over this!!


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## ElectronGuru (Jul 15, 2009)

That photo (forgot to say "click it") is from Mirage Man. I think he did a bit more than remove the anno. This particular setup is also in cool in that it also works for AW black C's.


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## sdlotus (Jul 15, 2009)

Thanks for all the tips guys.Even i was able to do a 3 cr123s in a 2 c mag.Love it .Now i want a bulb adapter and try other bulbs.How can i get the adapter and bulb.Thanks everyone..................stanley


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## ElectronGuru (Jul 15, 2009)

sdlotus said:


> Now i want a bulb adapter and try other bulbs. How can i get the adapter and bulb.



Hi Stanley,

Sockets are here
https://www.candlepowerforums.com/threads/219828

Bulbs are here
http://www.cpfmarketplace.com/mp/showthread.php?t=181713

Batteries are here
http://www.cpfmarketplace.com/mp/showthread.php?t=191277


And don't forget the lens and reflector. More info on everything is here.
https://www.candlepowerforums.com/threads/228965​


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## lctorana (Jul 15, 2009)

Another alternative, and one I am very fond of, is to do the 3xCR123A design, but use 2x18500 cells instead.

This give exactly the same voltage (about 7.2-7.4V under load), double the capacity and is reachargeable to boot.

And a 18500 cell is almost a bullseye match for a C cell for length.

You don't even need a pipe. Wrap the two cells laid end to end in about three turns of thick cloth, and you're done. The batteries are centred and cushioned. The cloth stays in the torch when you drop the batteries out, which is a useful feature.

The versatility of this mod, bulb-wise, is amazing:

7.2V argon bulb (eg PR18)
7.2-7.6V krypton bulb (eg KPR118, LWSA601)
7.2-7.6V xenon bulb (eg HPX60, LMSA601)
6V krypton bulb overdriven (eg KPR112, LWSA501)
4.8V krypton bulb massively overdriven (KPR113) - for the brave
Pelican 3804
Pelican 3853L, 3854L, 3853H, 3854H ("RoP" if you use metal reflector, glass lens and IMR cells)
1111, 1274, 1164, 64250 with bi-pin adaptor (ditto)
HPR71, GH24 - RoP-low competitors

It all depends upon how many lumens you want. Note that the first five on the list can be safely used in a cheap plastic throwaway 2C torch.

(I wouldn't stress 18500 cells, even IMRs, with really high-current bulbs like the 5761. That's when you bore out for 26500s.)


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## jaundice (Jul 16, 2009)

Guys;

Tonight I was working on making a mag 2D to 2x18650 conversion with PVC pipe and couplers, and I almost had an AW 18650 go high order on me!

Here's the thread: https://www.candlepowerforums.com/threads/236834

I appreciate your input. I'm new to flashaholism, so I want/need to learn from those more experienced than me.

I'm grateful that I spent a couple hours on "Smoke and Fire, Hot Cells and Close Calls" forum when I first got into LiCO cells, so I recognized the warning signs and took immediate action. From working in public safety in the past, I know to have appropriate fear and respect for what I generically refer to as "methyl-ethyl death" -type chemicals.

-John


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## sdlotus (Jul 16, 2009)

Thanks electron guru for the info for parts.Can't wait to order them and try them......................stanley


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## ^^Nova^^ (Jul 16, 2009)

I was thinking along these lines only a few days ago, but with a D mag. 

Is it possible to fix 3 CR123's abreast in a D mag (similar to the 3AA-2D adapters)? I was wondering about three parallel stacks of 3 CR123's in a 2D to run the 3854L bulb. If it doesn't flash the bulb, there should be over 4000mah of capacity with a long shelf life. Perfect standby torch.

Cheers,
Nova


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## ElectronGuru (Jul 16, 2009)

I think I've seen such a thing, but don't see it now...


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## Justin Case (Jul 17, 2009)

Why do you need to cut down the tail spring so much? I compared 2xRayovac C alkalines vs 3xSF123A and the SF123A stack is only 3mm longer.


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## ElectronGuru (Jul 17, 2009)

Justin Case said:


> Why do you need to cut down the tail spring so much? I compared 2xRayovac C alkalines vs 3xSF123A and the SF123A stack is only 3mm longer.



Great question. Its been so long since building this the first time that I forgot to mention it. 

To me, springs have two functions, holding the cells in place & making the (-) contact. Mag springs are legendary for their holding power. With normal C's, this is appropriate. The cells have HD steel plates top and bottom and are relatively heavy. So a strong spring is appropriate. The little 123's, however, are much lighter and more delicate. They need not nearly as much tension to stay in place and their (-) are smaller and thinner. 

I wasn't going so much for reducing length as reducing holding power. I wanted the new spring's power to be proportional to its new job. The cool part here is that since you're removing length, you can always starting by removing less and then work your way down if you want to remove more. Thats what I did the first time. Take off a half ring, test for strength, take off a half ring...

So to answer your question, I wanted a Mag tailspring (designed for Cs) to behave more like a SF tailspring (designed for 123's).


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## jaundice (Jul 17, 2009)

Justin;

See my last post above. I was making a 2D to 2x18650 conversion as you listed, and the strength of the D tailspring caused the protection circuit to crimp on the ridges on the bottom of the D switch. This caused a dead short in the cell, which then heated and blew all the electrolyte out through the PTC vent!  I NARROWLY avoided smoke and flame and toxic gasses! This was a serious close call. I credit the lack of smoke and flame to AW's excellent cells. This happened two days ago.

Anyways, it's my opinion that an unmodified mag tailspring is dangerous in combination with protected 18650s.

-John


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## jaundice (Jul 17, 2009)

Electron Guru;

I'm interested to see any tailspring modifications you know of for 2D to 2x18650 conversions, in light of my close call mentioned above. Any thoughts?

Thanks,

-John


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## ElectronGuru (Jul 17, 2009)

Hi John,

I'm more of a C guy. The only mod for D springs that I'm familiar with is the one for running C cells, by flipping the spring around (top/bottom, bottom/top). 

Consider starting a thread for this question, you'll get peeps better able to answer this than I.


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## Mjolnir (Jul 17, 2009)

I just made small tailspring for my ROP, which is running 2 18650s in a 2D maglite.

Since the main portion of the spring was too long, I flipped the spring around. All maglite springs have a smaller coil of metal at the base of the spring, presumably to hold in the spare bulb. I took this coil and made it smaller, mainly using a vice (you may need something thin and metal to use as a lever to make the coil protrude more). Using the vice, I managed to bend the tip if the coil, and center it so it makes contact with the battery. When I was done, I cut off the main portion of the spring, and put it in backwards. The tip of the new coil protrudes about a quarter of an inch from the tailcap, and works with both protected and unprotected cells without too much pressure.


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## supasizefries (Jul 17, 2009)

I have a 2C host awaiting a p7 mod...just waiting for additional parts. In the interim I decided to play around with it and stuffed 3 cr123's and a ROP low bulb in there. Man! I have to say it's pretty darn bright. And considering the price, this is a real bang for the buck mod. I haven't attempted long run times for fear of the cr123 primaries going


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## ElectronGuru (Jul 17, 2009)

Interesting! I wonder if the 4 ROP bulbs would survive the IMR16340 trio...?

Well of course, the 3854L would, it always does.


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## supasizefries (Jul 17, 2009)

Just for kicks I just swapped in a ROP HI bulb with the 3 cr123 primaries and it works also...only for a few seconds at a time at least.


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## Kestrel (Sep 4, 2009)

supasizefries said:


> Just for kicks I just swapped in a ROP HI bulb with the 3 cr123 primaries and it works also...only for a few seconds at a time at least.


Hmm, now I'm confused.  I thought that the ROP HI (Pelican 3854) was this build. Is the current draw from this bulb exceeding the safe limit from 3xCR123? I am coaching a person who is building this light (an otherwise-stock Mag 2C) w/ 3xCR123 (he’s not a rechargeable kind of guy) and I am about to purchase the pair of the Pelican bulbs for him. Will the 24W bulb from the 3854 set be an OK configuration on 3xCR123 in a Mag2C with no other mods? This person will really only want relatively inexpensive bulbs that are a straight drop-in for this host.

BTW looking at the Pelican bulbs from their website:
http://www.pelican.com/lights_accessory_detail.php?ID=244
http://www.pelican.com/lights_accessory_detail.php?ID=106
The second product is the 3854, I am assuming that the 3853 is for somewhat different voltage, a NiMH vs the SLA battery pack? I don’t know anything about the Pelican lights.


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## supasizefries (Sep 4, 2009)

At the time I posted, I was worried that the 123 primaries wouldn't do so well with the amp draw. I later discovered in THIS post, that it was ok. 



Icebreak said:


> Some good things about a ROP 1400:
> 
> 1) NiMh chargers. You might already own one. If your location is other than home and your light needs a charge; it's more likely to find a NiMh charger than a Li-Ion charger
> 2) Easy build.
> ...


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## ElectronGuru (Sep 4, 2009)

Kestrel said:


> I thought that the ROP HI (Pelican 3854) was this build. Is the current draw from this bulb exceeding the safe limit from 3xCR123?



This build is not so much about a specific recipe but a modification in form factor to put 123 cells in place of 2 C cells. Once ready, there are a variety of incan and LED options.

The primary consideration with all these upgrades is voltage. The example 1331 off two IMR16340's relies on the high amperage abilities of the IMR chemistry. 3xCR123A's are not a good match for 1331's or ROP bulbs. Their amp capacity is to low and in the case of the ROP, the voltage is to high. The only reason the 9 volts they are producing is not killing the 6 volt bulb in his example, is the massive voltage sag.

A better option for your exact setup is a Mag Xenon 5 or 6 cell bulb. This will give him the exact output of the full size Mag in the much smaller form factor. I built one of these, including colored lenses, and found it to be an excellent setup. But its not 4-800 lumens. For that much output, you need IMRs.


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## ElectronGuru (Sep 4, 2009)

supasizefries said:


> I later discovered in THIS post, that it was ok.



Careful. The mod he's asking about is an ROP off of 3x CR123A's in a 2C. The link to the ROP faq is twice as many NiMH cells in a 3C. That battery config is more closely matched to the amperage and voltage requirements of ROP bulbs.


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## ElectronGuru (Sep 4, 2009)

Kestrel said:


> Looking at the Pelican bulbs from their website, the second product is the 3854, I am assuming that the 3853 is for somewhat different voltage



There are two versions of the ROP bulb, the familiar 3854 is built for a 6.0v setup. The less common (but often more useful) 3853 is built for 7.2v setups.

My favorite ROP configuration is 2C with a pair of IMR26500's driving a 3853-H.


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## supasizefries (Sep 4, 2009)

ElectronGuru said:


> Careful. The mod he's asking about is an ROP off of 3x CR123A's in a 2C. The link to the ROP faq is twice as many NiMH cells in a 3C. That battery config is more closely matched to the amperage and voltage requirements of ROP bulbs.




Yeah that's what I understood as well. #4 on the list, in the post that I quoted from states that 3 x cr123's were possible. Did I miss something?

Edit: It actually says 3 x 123's. Doesn't specify primaries or rechargeables. I'm sure rechargeables are a better choice.


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## Kestrel (Sep 4, 2009)

OK, thanks for the info. This guy I'm helping is a 'push the limits' kind of guy, so I'm trying advise him on the brightest build for his (otherwise-stock) Mag 2C. He already has CR123 lithium primaries and isn’t interested in rechargeables.

The options for drop-in bulb replacements, from what I understand:

Pelican 3854 (Hi). ~800 lumens. Outer edge of what’s feasible on 3xCR123, but he really wants to try this one so I’m going to have to get him one. Q’s: Will any of the stock Mag parts melt, and I am assuming that the bulb would die pretty soon so I should probably get him a spare?
Mag Xenon 5D bulb (their higher-output ‘Mag-num Star’ bulb line). Also slightly overdriven on 3xCR123 by my calculations, but more feasible overall. Any guess on the estimated lumens for this one?? I might be able to sell him on this one if the 3854 (Hi) is just too impractical (he doesn't care about runtime on this) and I can give him a decent lumen estimate.
Pelican 3854 (low). ~300-400 lumens. Somewhat overdriven. Feasible.
Mag Xenon 6D. Not significantly overdriven on 3xCR123. Resonable IMO but I don't think he'll go for this option.
My buddy really wants the outer edge of what is possible (for no additional parts), but I don’t really want to get him started by melting his plastic Mag parts or introducing him to the term ‘insta-flash’. 

Edit, much later: If anybody is interested, I've repeatedly come across postings by much more knowledgeable folks than I here on CPF that the Mag Xenon 5D bulb is a poor choice compared to the Mag Xenon 6D. In addition, EG's post#40 here in this thread appears to be right on the money.


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## supasizefries (Sep 4, 2009)

I'm pretty sure the stock plastic reflector and probably lens will melt with the RoP HI bulb with any "normal" usage times.


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## Kestrel (Sep 4, 2009)

supasizefries said:


> I'm pretty sure the stock plastic reflector and probably lens will melt with the RoP HI bulb with any "normal" usage times.


Thanks, I'll advise him of this. Once I told him the magic words :sigh: (~800 lumens, it will be brighter than anything I own), he really wants this. I can tell him to keep his runtimes with this bulb down to a few minutes perhaps...?


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## ElectronGuru (Sep 4, 2009)

supasizefries said:


> _4) Flexibility. You can run all the 2C 3X123 and 6cell HotWire solution lamps in it, CA1499, CA1057, WA1111, Pelican Big D 6V SLA, Krypton 5C, etc., etc.
> _
> Yeah that's what I understood as well. #4 on the list, states that 3 x cr123's were possible. Did I miss something?



Thanks for pointing this out. I've read of CR123's exploding when the amp draw is to high. This post dates back a few years and may not be fully tested. In any case, I recommend NOT running an ROP H bulb on CR123's.


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## ElectronGuru (Sep 4, 2009)

Kestrel said:


> My buddy really wants the outer edge of what is possible



Based on your options/limitations, I recommend going with the 3853-L. Then keep the 3853-H's for a better project. 

Either of the Mag 5/6 bulbs will be half the output of the L.

Its your call on the plastic components. The L bulb, in addition to being safer with the cells, is also less likely to melt the plastic bits.


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## Kestrel (Sep 4, 2009)

Thanks guys, I really appreciate the help.
K


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## ElectronGuru (Sep 15, 2009)

Someone made a video!

http://www.youtube.com/watch?v=bSYZxBNhIN0


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## Kestrel (Sep 15, 2009)

ElectronGuru said:


> Someone made a video!


Pretty nifty. I noticed that he used a 6D Xenon bulb instead of the 5D (let alone the 3853-L), so a pretty conservative build I guess. I would think that the spring tension issue is critical - I wouldn't be able to sleep knowing my CR123's were getting crushed by that monster spring.


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## greenad (Oct 27, 2009)

Hello everyone, 
I am a long time viewer but I registered to make a quick comment. Remember that Eveready 2AA that you did the 3x123a and kpr112 mod to and promptly melted it? The tail spring and retainer from that flashlight will drop right into the back of your 2c mag. You actually have to stretch it a bit. Then you do not have to cut the original spring to do this mod.
My backup bulb is the Nite-ize 6d LED.

Have a great day.
a


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## ElectronGuru (Oct 27, 2009)

Wow. I think thats the best 'long time listener, first time caller' post I've never seen. Welcome!


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## Swedpat (Oct 27, 2009)

Interesting thread and nice pictures. HERE is a post I made about my 2C/3xCR123 mod. Not 800-900 lumens but around 200. The difference of runtime will be huge I understand. 

Regards, Patric


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