# another M6-R with MN61



## kalengkong (Oct 6, 2005)

Hi all! 
I just wanna share what I've been doing .
I dont know if somebody has already done this, 
Basically Im using 6 rechargeable Li-ion batteries from ebay (the 3.7V one), 
to put inside my Surefire M6 - so the total Voltage is = 11.1V.

then to accomodate this voltage rise, Im using MN61 BULB (for Surefire M4 - 12V one) - bought from cpf member "somelamp"
(hi somelamp!)

And it is working beautifully!!. Cheap 350 lumens.  
I've tried to turn it on continuously, and it results with 22 minutes of Full Power light, with these 700ma Li-ion cells.
then about few seconds yellow beam after that (then I turn it off quickly).

I want to post beam shots, but dont have digital camera 
(i have a $1000 flashlight in total, but cant afford to buy $200 digi-cam)
*typical flashaholic* hehehe...
I'll try to borrow my friend's digi-cam , and post it here.

Thank you for reading.


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## js (Oct 6, 2005)

kalengkong,

Yes. It has been done before, but so what?

It was good then, and it is good now. And far cheaper than an M6-R I suspect.

I do wonder what the voltage under load is, and how many actual lumens are being produced. It could be MORE than 350! It could be less. We wouldn't know unless someone bench tests this setup to get applied voltage at the lamp.

Still, it doesn't matter too much. I only wanted to point out that despite the Li-ion volumetric energy density advantage over NiMH, an M6-R still manages 630 lumens constant, undimming, for 19 minutes.

I just love that.


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## kalengkong (Oct 6, 2005)

Hi js, 

no no no , i think, you misunderstand my post.
I didn't put my post here to 'compete' with your M6-R project.
yours is far away more advance than my 'beginner project'.

and actually your M6-R pack is one on my wish-list. but dont have the money now. need to buy a new lcd. 

I just want to share my experience here.  thats all.

PS: about the lumens, yeah, I dont know how many lumens does it produce, it might be more than the spec said, since the 11.1V is quite high i think.


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## bwaites (Oct 6, 2005)

Kaleng,

Jim wasn't criticizing your post, he was saying that it has been done, but it is still a good modification, especially for the cost!

I should try this, but time is at a premium for me right now.

Bill


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## IsaacHayes (Oct 6, 2005)

I'd be carefull with that many batts in series. Good thing you turned it off at first sign of diming. I wouldn't want one to reverse charge and then have a hand held grenade full of 6 flaming li-ions!!


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## js (Oct 6, 2005)

Kaleng,

What Bill said!

I didn't mean to say anything negative at all about what you've done. It's a good idea!

I only mention the NiMH thing because I am often taken to task for using NiMH, when Li-ion is the "latest and greatest". But even though it is the latest and greatest, I still can manage to best it with my NiMH M6-R pack. Hmmm. Li-ion must not, in all ways at all times in all situations be the best.

Just trying to blunt the favorite axe that some people grind and then try to use on me. Although that hasn't happened for some time now.

That said, two 18650's will direct drive the MN21 nicely and have a decent runtime, although I can't remember how much at the moment. But trying to direct drive the MN21 with two 4/5D Li-ion's would almost certainly insta-flash it when the cells were fully charged. Plus, they wouldn't quite fit, even without protection circuitry. Add the protection circuitry and they definitely WON'T fit.

Another option is to use three Pila 168s's in series in a special holder, which Kiu did back when I was working on the M6-R (but was still keeping it secret) in his Rechargeable in SF M6 (PILA\'s) 2xx lumens thread. This is essentially the same, electrically, as what you are doing. You have two parallel stacks of three R123's; he had one stack of three 168s's. In both cases the open circuit and under load voltages are similar, I would think, although he used the MN60 and you are using the MN61. But there was no reason why he couldn't have used the MN61 as well. Except maybe some caution and concern over the current draw.

In any case, this method that you are using is a drop-in mod, whereas Kiu had to make up a special battery holder. All your method requires is some R123's and an MN61, both of which can be obtained on-line, on demand. No waiting for some slow coach to finish making up a special battery pack or something.

Although, as I said before, I know I read someone doing this. I think it was in the incan forum, and it was about a couple or three months ago now, IIRC.


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## kalengkong (Oct 6, 2005)

thanks for all the reply. 
I think I missed a lot in this forum, since i've been 'away' for a while. 
HMmmm.. I m also worried about the Li-ions in series like that. 
thank you for the info guys. you guys really helps me a lot . 

js, MN21 with 2 LI-ion? hmmm interesting... hehehe.
I think i would try that one tonight.
(hmmm yea, 7.4V i think will be alright to run MN21) hmm hehehe... i like this.


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## 270winchester (Oct 6, 2005)

Okay, just feeling stupid here, but how about Li-Po? They are designed to take MUCH higher current than Li-Ion can at this time, and there are a lot of 11.1volt 2600+MaH packs available on line, all we need is to custom request a shape to fit in the M6...

Granted Li-Pos aren't the safest thing around, but neither is pulling 2-2.5 amps from a series of 3 R123s....


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## kongfuchicken (Oct 6, 2005)

Question: is that using protected li-ions?
I'm guessing not but then why use the M4 HOLA instead of a safer LOLA?


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## tch_popeye (Oct 6, 2005)

270, I'm with you. For the experienced LiPo user, who is aware of the dangers, you could get some fantastic energy density shoved into an M6... if only the darned rectangular packs would fit nicely. Add a little bit of smarts to either regulate and/or prevent overdischarge, and you're talking about my dream light! 

-Trev


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## js (Oct 7, 2005)

The newer Li-ion, especially the 4/5D size, would more than handle the current. No need to go to Li-poly for a 5 amp draw in this case. Even the LG 2400 mAh 18650's will handle the 5 amp discharge--barely, but still, they do it.

The problem, as tch_popeye points out, is that the Li-polys are prismatic cells, and thus don't fit nicely into a round hole. So you loose energy density there. The best energy density would come from the 4/5D's, two of them in series, but made a little bit shorter than standard 4/5D's in order to fit. But then you'd have to worry about instaflashing, or space to fit regulation circuitry of some kind.

And, in point of fact, there are two types of energy densities: gravametric, and volumetric. RC people are much more interested in gravametric energy density: energy per gram. Flashaholics are much more interested in volumetric energy density: engergy per unit volume. And it turns out that NiMH isn't that far behind Li-ion or Li-poly if you use that measure. It is still behind, to be sure, being, IIRC, only 80 percent of Li-ion energy density. BUT, when you start to take into account of high draw rates relative to capacity, then NiMH start to get closer, meet, or even exceed Li-ion or Li-poly volumetric energy density. Not so with gravametric, especially with Li-poly, due to the lack of a metal casing.

Anyway, if we could get two 4/5D's into an M6, and if the MN21 were a bit higher in voltage so that it could safely be direct-driven, or if we just pretend we could fit the regulation circuitry in the tail-cap or something, we'd get on the order of 40 minutes of runtime!

A lot of "ifs" there, though.


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## Ginseng (Oct 7, 2005)

js said:


> Just trying to blunt the favorite axe that some people grind and then try to use on me. Although that hasn't happened for some time now.



Jim,

"Udam..." 

Wilkey


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## KevinL (Oct 7, 2005)

js said:


> Even the LG 2400 mAh 18650's will handle the 5 amp discharge--barely, but still, they do it.



Aha, that means my ROP/LE design will still have a little bit of leeway. 4 amps here. 

Ginseng: better go back into hiding before js grabs the axe and looks for you for mentioning that


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## js (Oct 7, 2005)

Ginseng said:


> Jim,
> 
> "Udam..."
> 
> Wilkey



LOL! OMG! Exactly.

Ah, I'm glad we can laugh about it, especially you. I suppose that you probably keenly miss having your own chronicler and biographer and personal interpreter here on CPF --who, as it turns out, knew you better than you knew yourself, and --sadly-- turns out to have had a much darker view of your motivations, decisions, and career.

We must all, though, sooner or later bow down before the superior wisdom, and accept the fact that we are ALL loosers for not having made an E2e sized HID light with miniaturized ballast running li-ions and named after a rather attractive young woman. Pathetically, we continue on with such rich mans toys as the M6-R and the Aurora2. Woe is us. Hear us sob.


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## js (Nov 8, 2006)

It seems high time to bump this thread to the top!

A number of people are obviously intereted in a rechargeable solution for their M6's, but are leery of pre-paying for an HD-M6, which has seen repeated delays and whose delivery date is still uncertain. In addition, many would like a "drop-in" solution.

Forgive me, everyone, for not making more M6-R packs, but the amount of work-bench time involved in each one is substantial, and having made 40 of them already, I am not eager to make very many more. I will, possibly, make a few more for a sale, and/or for a CPF benefit auction, but certainly nothing like the numbers needed to supply the demand.

So, until the HD-M6 is field tested and proven and is actually shipping, I would offer this solution posted by kalengkong.

It needs some exploration and testing, however, because the most powerful R123 cells--the Powerizer, and the LightHound R-CR123--will probably hold higher voltage under load than the cells used in kalengkong's case. Or maybe not?

But I would suspect that the MN60, at least, will be viable (and bright!).

Some cautions:

1. Always charge the R123's separately, and check voltages of each individual cell before inserting into MB20 holder to ensure they are all at the same state of charge.

2. Turn off light immediately upon dimming. Do not over-discharge.

3. This is experimental--your lamps may explode or flash at turn on. So if you choose to explore this option, beware. It is barely even proto-typed at this point, to my knowledge. The MN60 is the safer bet than the MN61 explosion-wise/flash-wise.

If there are people who are running R123's and the MN60 or 61 in your SureFire M6's, *PLEASE SPEAK UP!*

I don't know what the runtimes or outputs of these configurations will be, but the MAJOR advantage of them right now, is that they are availabe (wait for it . . . . .)

RIGHT NOW. (DON'T wait for it!!!!)

Just buy six or seven or eight (spares are good) Powerizer or LightHound R123's and either an MN60 or MN61 (or both), and you are ready to try out your very own rechargeable M6. Nothing to modify or build (or wait for others to mod or build) And be part of field testing and exploration in the grand tradition of CPF at its best--a community effort.

You could also try the N61 or N62 12PM lamps, but their focus is slightly off when used in the M6 head--at least according to what Size15s has said--so the MN60 and MN61 are better choices, beam-wise.

And always remember: Li-ions are potentially DANGEROUS animals. Be aware of proper use and care and potential dangers.


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## dizzy (Nov 8, 2006)

js, how about using the 3.0v rcr123's? I have 6 of these, and when I take them off the charger they read 4.2 volts each but heard they drop down close to 3.0v under load, because they have some kind of regulation circuitry in them.

I have no facts about these cells and make no claim to whether they do opperate at 3 volts under load, but if they do, would they work with the MN20 lamp assembly?

Thanks for bumping this thread also. I had not seen this one before and it seems very promising that I can get some kind of rechargable solution going while I wait ( quite long, as you well know ) for the other rechargable solution to become available.


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## js (Nov 8, 2006)

dizzy,

It's a great idea!

I just know next to nothing about the 3 volt / protected Li-ion cells. Last I checked (some time ago now) there were two main problems with using them to run the M6: the protection circuitry sees the filament as a short circuit and won't let the cells turn on, and the current handling capability is not as good as the unprotected ones.

The MB20 is a 2p3s, ie. two stacks of three series R123's. So to run the MN21 HOLA, each stack would need to deliver about 2.5 amps if the voltage they maintain is about 6.8 or so volts. ie. their discharge curve at 2.5 amps would need to be about 2.3 volts per cell. This is obviously problematic, because if the voltage is THAT low, the cells are sucking pondwater, and the curve will be steep and the output too variable.

So, as you rightly suggest, the MN20 is something to think about. It's drawing about half the current of the MN21, so each stack would need to handle 1.2 amps or so. Entirely do-able I should think. But what about the voltage? Well, if each cell maintains 3 volts, we end up with way too high a voltage (9 volts). The operating voltage of the MN20 is something like 7.6 volts. divide by 3 and you get 2.5 or so. That may be a realistic number for voltage under a 1.2 amp load for a 3 volt R123.

Or maybe not. Does SilverFox have graphs for the 3.0 volt R123's? Or is there a thread that does?

Because the MN20 is already driven pretty hard at 7.6 volts. I doubt it would take anything much over 8 volts.

It's certainly something to look into, though! First thing to do is get a link to discharge graphs of the 3 volt 123's.


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## js (Nov 8, 2006)

As a post-script, I will point out here what I have said elsewhere, and that is that people would be wise to clearly and rationally evaluate whether or not primary 123's wouldn't be a smarter choice than a rechargeable solution.

The M6 with MN20 installed running on primary 123's is one heck of a flashlight. One of my very favorites, FWIW. And you get an hour of runtime from 6 123's. And 400 lumens of output--bright white output, too. The MN20 has a very high CCT for a production light.

So, it's just a suggestion to consider. Nothing more, nothing less. But especially relevant here, where the experiment could mean blowing up a $30 lamp and sullying a very expensive turbo head.


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## dizzy (Nov 9, 2006)

I think I will pass on using the 3.0volt rcr123's in the M6 until I get more facts on them and their safe usage. I would not want to screw up a lamp or a turbo head or both, just to save a couple bucks on primaries.

The use of primaries, though, with the MN20 is sound advice, which I will use. I just resently got an MN20 ( just became available again ), but never really even checked it out yet on fresh cr123's. Is it really putting out 400 lumens? 

Thanks again for the information, God knows I can always use the help.


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## js (Nov 9, 2006)

dizzy,

Good plan!

And yes, from all of my testing, I find that it is indeed putting out 400 lumens on fresh cells. And the MN21 is putting out 630 or so.

This is based on comparison with the TigerLight 375 lumen LA, which was tested in an Integrating Sphere, and on the MagCharger-1160, which is putting out 450 lumens based on re-rating forumulas and a bulb-lumens to torch-lumens conversion factor, which was also tested via an integrating sphere.

The issue of just how many lumens something is putting out is a thorny one. Long ago, people noticed that the SureFire lights lumens ratings just weren't commensurate with the lumens ratings from the Welch Allyn website for their lamps. The SF lights were under-rated relative to the WA ratings. Ingenius testing via ceiling bounce tests and light meters, suggested a rough figure to convert one to the other.

And on top of that SF under-rates their lights. For example the SF E2e clocked in at 83 lumens in the Arc Flashlight IS tests. Yet it is only rated at 60.

See bLu vs. tLu: IS confirms 65% conversion factor for more discussion on the subject than any sane person could possibly want to digest in one sitting. Ignoring the in-fighting, and concentrating on the informative parts goes a long way towards making it more palatable.

Anyway, short answer is I call it a "400 lumen" lamp in order to more properly rate it so that the reality fits with the CPF-assigned values. It really is just slightly less bright than a 450 lumen MagCharger running the 1160, and slightly more bright than the TigerLight with the 375 lumen LA installed. So if we accept the one set, we must accept the other.

And the TL HOLA was tested in an IS. I know because I'm the one that sent it to be tested at LSI of Arizona and got back a lumens/MSCP rating.


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## js (Nov 10, 2006)

OK. At least one person is going to try this idea, and I will also probably test it myself, if this person doesn't blow the lamp.

For sure, the MN60 will work, but the MN61 may blow against the newer, more powerful R123's. Or it may not. We shall see.

I talked with SilverFox about this idea today on the phone, and he had a great idea of his own to contribute. And that was that we should make up a 6 R123 charging holder that places all 6 R123's in parallel. That way you ensure that they are all at the same voltage, while still charging all of them at once!

So if anyone knows of comercially available R123 / A sized battery holders, feel free to chip in. Or if anyone thinks he or she could make something like this for people, please also tell us about it.


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## nuggett (Nov 13, 2006)

Got the MN61 bulb today. Only had time to play with it for a few minutes, but runs great so far. very bright. I will report back in a few days exactly what that means, but it is brighter than the MN20.


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## js (Nov 14, 2006)

nuggett,

Interesting! Good that it didn't blow, at any rate, but not good that it isn't brighter then the MN20. I was expecting it to be at least as bright or brighter. If you check out the Kiu thread link you will see he claims that the MN60 on three Li-ion cells is brighter than the MN20. So one would expect the MN61 to be even brighter than that--or that it would insta-flash. A voltage under load measurement would be lovely in this situation, but is hard to do on this setup.

Keep us informed!

What R123 cells are you using, by the way?


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## js (Nov 14, 2006)

*duplicate post*


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## js (Nov 14, 2006)

nuggett,

It dawns on me that maybe you were saying that the MN61 driven by R123's in the stock MB20 holder was not as bright as the *MN21 M6 HOLA*. Is that the case? Because if that's what you meant, then, yes, absolutely that makes perfect sense. The MN61, even over-driven, would not be quite as bright as the M6 HOLA.


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## nuggett (Nov 14, 2006)

Yes, what I meant to type was the 61 IS brighter than the MN20.
I am using Lighthounds Blue RCR123 800.
I mean to add, the beam is a nice oval shape.


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## js (Nov 14, 2006)

nuggett said:


> Yes, what I meant to type was the 61 IS brighter than the MN20.
> I am using Lighthounds Blue RCR123 800.
> I mean to add, the beam is a nice oval shape.



STELLAR!!! This is great news. Thanks for the info!

Have you done a runtime test yet? (Be sure to turn off at dimming--keep an eye on things--do NOT let the cells over-discharge).


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## LED61 (Nov 14, 2006)

Hmmm, accidentally stumped into this thread JS. Great news for me as I just unpacked my new M6 with spare lamps. Lots of new stuff here.


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## Flea Bag (Nov 14, 2006)

Actually, I was hoping for someone to produce a very simple-charging, true-drop-in solution for the M6 that consists of two types of battery holders. I'm sure many others have thought of this before:

A 2x18650 holder which will allow the cells to pop out of the battery carrier like the standard MB20 so they can be conveniently charged by a standard AW/Wofl-Eyes/Pila charger which many of us have. Safety is better having only two cells to worry about and the batteries will be easily interchangeable with other setups. If the 18650s are too powerful for the N2 and MN15 bulbs then hopefully the battery holder can also take the extra length of 2x17670 to reduce chance of blowing the bulbs.

Then fabrication of a 3x17670 holder will allow power for the MN60&61. Again, there is no need to purchase a dedicated charger to charge a battery pack and in terms of safety, there are only three cells to worry about.

Together, these two battery holders can turn the M6 into the most versatile li-ion platform for any MNxx lamp assembly. The convenience, simplicity, safety, interchangeability and cost savings would be pretty nice I think.


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## wquiles (Nov 14, 2006)

Flea Bag said:


> Then fabrication of a 3x17670 holder will allow power for the MN60&61. Again, there is no need to purchase a dedicated charger to charge a battery pack and in terms of safety, there are only three cells to worry about.


You mean like the 3x17670 I show at the end of this post ?

I have been thinking about putting one of the remaining LVR's from js on such a package to drive the MN16/MN21 bulbs, but from a LiIon solution. I just need to find the time to work on it !!!

Will


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## nuggett (Nov 14, 2006)

Building with white trim is about 50 yards
MN20



MN21



MN61


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## nuggett (Nov 14, 2006)

duplicate


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## wquiles (Nov 14, 2006)

GREAT beamshots !!!

Will


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## js (Nov 14, 2006)

Nuggett,

NICE!!! Thanks so much for taking the time to post those.

*WE'RE LOOKING GOOD HERE PEOPLE!*

Flea Bag,

Well, there are MANY possible solutions to this problem, and if you check out the Kiu link you will see he made a three Pila cell holder. Or two 18650 cells will also fit, and are a good match directly against the MN21.

But fabricating a battery holder is not an easy thing to do, particularly for someone who isn't into modding or isn't "handy" or who just doesn't have a lot of time to spend at the workbench, or whatever . . .

Point is that I was looking for something VERY SIMPLE, yet VERY EFFECTIVE. Something that anyone could do with a few internet orders. No waiting for a modder to fab up 60 battery holders, or such-like.

This is dead simple. Pop in R123's into the MB20, drop in your MN61 or MN60, and go.

The only issue is charging, and yes 6 cells are harder to deal with than 2 or 3.

BUT, it's pretty easy to come up with a 6 123 holder that puts them all _in parallel_ so that you ensure that they all charge to the same voltage, and there are a number of good charger choices out there--inexpensive, yet effective. The simple charging holder won't need the strength or ridgidity or have the size constraints that an MB20 replacement holder would need. Heck it could even be a bunch of wired-together CR123A battery holders. I haven't researched this yet, but trust me, I will. I think we will be able to find a number of good solutions that will enable easy re-charging, and SAFE recharging.

I should point out that if you have some kind of charging clamp, such as cy made and posted about, then you CAN charge the whole MB20 on a 3 cell Li-ion setting, _so long as you use a DMM to check the voltages of all the cells at the end of charge to ensure none is too low or too high_. They should all end up very near 4.1 volts, although some chargers allow you to charge to 4.2 volts--but 4.1 is marginally safer and gives more cycle life.

Anyway, what I'm saying is that this is a solution for "the rest of us". Get about $24 in cells, get a $30 lamp, and a $20 charger, and you are good to go. Even if you do have to charge 2 R123's at a time, it's still not a big deal. You still have your rechargeable M6, without any waiting, and without paying much money.


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## Flea Bag (Nov 15, 2006)

wquiles said:


> You mean like the 3x17670 I show at the end of this post ?
> 
> I have been thinking about putting one of the remaining LVR's from js on such a package to drive the MN16/MN21 bulbs, but from a LiIon solution. I just need to find the time to work on it !!!
> 
> Will



Yep I think any li-ion solution in such a holder would be an excellent idea for non-modding (and lazy folk) like me if only someone could produce them and sell them in decent numbers. I guess the challenge lies in fabricating the plastic and having reliable contact points that will allow easy insertion and removal of batteries for charging but I wouldn't mind paying MB20 prices of $80-90 for such a battery holder.

Actually, I wouldn't even mind paying a few hundred dollars as a prepayment to fund the project as a small contribution to CPF!


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## Flea Bag (Nov 15, 2006)

js, I think you underestimate how lazy I am!  

Charging 6 x R123 (even in an MB20) and testing each of their voltages is a bit too troublesome for me! Swapping batteries in the field would also be a bit difficult unless a second MB20 is purchased and those things aren't that cheap either! I'm not technically competant but 6 x R123s trying to push an MN21 is a lot more scary to me than 2 x 18650. But I think I'll still give it a try. :lolsign: 

Actually, I think fivemega's holders are quite close to being the perfect 3x17670 or 2x18650 battey holders. They just need to be adjusted for length, have contacts similar to those on the MB20 and for the plastic to be cut a little to allow the cells to slide in and out with ease. Easier said than done of course...

Bottom line is, I don't mind paying for the extra convenience and safety as long if that means that I'm able to stick to the existing li-ions and chargers I have which also fit like a glove with my other SureFires setups. I'm sure there are plenty of M6 owners in the same situation as me. I don't think it's economical for each one of us to make our own 3x17670/2x18650 battery holders but if someone does it in bulk, I think it would be profitable and the long-term benefits would be worth paying and waiting for. I was thinking of using the M6 more regularly and when that happens, convenience and safety will be even more important. 

I did approach a CPF member to see if he can come up with a holder but I have to be patient and wait as he's currently very busy with other projects.

I've always loved your work Jim, would love to see what comes next...


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## LED61 (Nov 15, 2006)

Nugget, don´t mean to hijack the thread here but I am very interested and from your previous post I gathered the MN61 would be brighter than the MN20. With these great beamshots it looks like the MN61 outshines BOTH the MN20 and MN21. Could you confirm these beamshots are with Lighthound R123 800mah? 

That is impressive!!



nuggett said:


> Building with white trim is about 50 yards
> MN20
> 
> 
> ...


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## LED61 (Nov 15, 2006)

Jim, pardon my ignorance but just a few questions.

1) Why is the M4 MN61 lamp nugget used able to handle higher voltage than MN21 ?

2) Do you think a 7.2 volt rated bulb will instaflash if driven at 9-9.5 volts ?

3) If we use RCR 800-900mah capacity cells would we discharge the cells at 3C if used with MN21 ? (dangerous?)

FWIW, tenergy RCR123´s come at 3.6 v off the charger and drop to 3.2 in 12 ms and have 900 mah capacity. Then, working voltage is around 3V--still too much? Those are the lowest voltage rechargeables I am aware of.

Some specs here http://batteryjunction.com/rc390reliba.html


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## js (Nov 15, 2006)

OK, first of all, *DO NOT DRIVE THE MN21 WITH R123's IN THE STOCK MB20 BATTERY HOLDER!!!*. You *WILL* blow the MN21.

This is mainly in response to flea bags "I'm not technically competant but 6 x R123s trying to push an MN21 is a lot more scary to me than 2 x 18650. But I think I'll still give it a try."

Don't give it a try, flea bag. Bad idea bad idea!

LED61,

1. The MN60 and MN61 are made to work against four series CR123A cells, and are used in the SF M4. Thus they are designed to work with higher voltages, by . . . well . . . design!

2. Which 7.2 volt lamp? It all depends on what life it had a 7.2 volts, but almost certainly you would flash it at 9-9.5 volts, unless it was SERIOUS long-lived at 7.2--like thousands of hours of life.

3. We are not using the MN21. That's for starters. Second, the MN61 draws about 2.8 amps. This current draw is shared by *two stacks* of R123's. So each stack only has to deliver less than 1.5 amps--within the safe discharge rate of Li-ion cells.

And for the record, going by SilverFox's data, it looks as if the Lighthound cells and the Powerizer cells (both unprotected "industrial" cells) are the only ones to consider for this set-up. If there are others not covered by SilverFox's thread, please post about them here!

Hope that cleared some things up.


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## LED61 (Nov 15, 2006)

Fully understood Jim, so I guess the MN61 will be driven by around 10 volts similr to stock light and around 28 Watts output power ?


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## nuggett (Nov 15, 2006)

Yes, the MN61 is brighter than the MN21. Amazing, isnt it! I am now using new, MP cells in order to keep the dedicated to the M6. I intend to walk the dog tonight and do and extended run. Last time I did that with the stock M6/MN21/123, the grip got very warm from the batteries after about 5 min. So tonite, I'll compare.


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## js (Nov 15, 2006)

nuggett,

Holy crap! Now THAT is cool!

What did you mean by "I am now using new, MP cells in order to keep the dedicated to the M6." Not clear on that sentence.

Were the beamshots done with fresh 123's driving the MN21 and MN20? In the photos the MN20 looks decidedly less white in color than I am used to seeing. Could just be the vagaracies of the camera and underexposure and so on, but just thought I'd ask for the record.

Anyway, either way, this is incredibly good news!!! Awesome! I didn't expect that the MN61 on 2p3s R123 would be as bright as the MN21, let alone brighter.

Rockin'. Very nice. I hope we aren't overdriving it to the point where its' life is impractically short, though.

If the R123's are holding 3.5 volts per cell, that's 10.5 volts at about 2.85 amps (according to CPF reports on the MN61 on 3 li-ion cells) which is 29.9 watts. However, perhaps the 2.85 amps is wrong, or with only a single stack of 3 R123's and not two stacks in parallel. In which case the draw might be higher, and the power correspondingly higher as well. For reference, the MN21 on fresh 123's is running at 6.8 volts and drawing very close to 5 amps, which is 34 watts.

But these are just educated guesses from me at this point. What I really need to do is put this setup on the test bench and measure current draw and voltage and get a discharge curve, and then compare against a single stack of 3 primary 123's for reference. And check CCT against known lights like the A2. And so on.

I will so this at some point if no one does it before me. And I think I will probably get myself an MN60 and MN61 and some Powerizers or Lighthound cells very soon.

But, however that may be, I will definitely try to figure out a cheap and effective way to make a 6p1s 123 holder.

Looking forward to the heat report and the runtime test. Thanks so so much for trying this out and posting about it, nuggett. I'm thrilled with this whole situation.


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## LED61 (Nov 15, 2006)

I must be missing a piece of info here. please bear with me guys. The MN21 has lower output in the beamshots and it runs on 34 watts power. How is it possible the MN61 is less power and brighter in this configuration ?


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## js (Nov 15, 2006)

LED61,

No problem. It IS confusing. The issue is that a lamp can be driven over a range of voltages, from where it produces only heat, to where the filament is just about to vaporize because it is so close to the melting point of tungsten.

The MN61, _driven by 4 primary 123's_ is less powerful than the MN21 driven by two parallel stacks of 3 primary 123's (6 total).

True. However, we are not using 4 primary 123's. A primary 123 under near maximum load (about 2.5 amps) holds around 2.2 to 2.3 volts each. So 4 of them will hold about 9 volts or so, depending on their temperature and state of charge. But we are using (aren't we cool!) 2 parallel stacks of THREE LI-ION rechargeable cells. I don't have SilverFox's graphs in front of me, but IIRC a Powerizer of Lighthound R123 will hold about 3.5 volts with a current draw of around 1.2 to 1.5 amps (i.e. each stack only needs to provide half the total current).

SO, three cells at 3.5 volts/cell is 10.5 volts. Quite a bit more than 9 volts, isn't it? This will mean higher current draw. Just exactly how much really should be determined by _measuring_ it--both voltage and current in the setup being considered.

However, there are handy dandy rules of thumb for re-rating a lamp of known parameters, to a different voltage. These are known as the re-rating formulas. Here they are:

Ir = (Va/Vd)^0.55 * Id
Cr = (Va/Vd)^3.5 * Cd
Lr = (Vd/Va)^12 * Ld.

Here the "r" 's represent the re-rated values and the "d" 's represent design values. The "I" is current draw, the "C" is mean-spherical candlepower, which is proportional to total bulb lumens (multiply by 12.5 or something like that), and the "L" is lamp life--number of hours of operation you are likely to get. It's a statistical thing. At the L rating, half of the lamps in a group sample will have burnt out. But half will be still going.

Notice that the Life re-rating is HIGHLY non-linear: a small relative change in applied voltage will mean a large change in lamp life.

*cough* OK. More info maybe than you wanted. Let's apply it.

If the MN61 at design is 9 volts, 2.5 amps, 350 lumens and 35 hours of life, what happens at 10.5 volts. OK. First, let's adjust the 350 lumens figure. SF always under-rates by at least 20 percent. So let's just crank that up to 420 lumens, which is still conservative.

Ir = (10.5/9)^.55 * 2.5 amps = 1.16666^.55 * 2.5 amps = 1.08 * 2.5 amps = 2.72 amps.

Lr = (9/10.5)^12 * 35 hours = .157 * 35 hours = 5.5 hours.

Cr = (10.5/9)^3.5 * 420 lumens = 1.715 * 420 lumens = 720 lumens.

So yes, it does look as if the MN61 at this voltage will out output the MN21. But let's hope that 35 hours of life at 9 volts is very conservative! Otherwise we're looking at a scarily short life span.

Going back to the current, 2.72 amps disagrees with the CPF info I found in one of the incandescent forum sticky threads of interest. They claimed 2.85 amps on three Li-ion cells. A measurement will be required in any case, but I should point out that the re-rating formulas are only approximate, and the farther away you go from design the less accurate they are. On top of that, we actually don't really know the design values of this lamp. I just guessed them into the formulas.

Also, keep in mind that power is NOT going to tell you lumens, unless you also know the CCT or the life-rating. In other words, the harder you drive a lamp, the shorter the life and the greater the efficiency. At 3300 CCT, you get about 30 lumens/watt. Each 100 CCT up or down adds or subtracts about 3 lumens/watt. The practical maximum you can achieve is somewhere around 37 lumens per watt. More than that and the filament is so close to melting that it is too fragile and too short lived to be useful.

So, short answer: MN61 brighter because it is being driven harder than stock, equates to more power coupled with greater efficiency.


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## Flea Bag (Nov 15, 2006)

js said:


> OK, first of all, *DO NOT DRIVE THE MN21 WITH R123's IN THE STOCK MB20 BATTERY HOLDER!!!*. You *WILL* blow the MN21.
> 
> This is mainly in response to flea bags "I'm not technically competant but 6 x R123s trying to push an MN21 is a lot more scary to me than 2 x 18650. But I think I'll still give it a try."
> 
> Don't give it a try, flea bag. Bad idea bad idea!



Eeps... I misunderstood and thought that you were talking about 6 x R123s in a modified holder so I replied in that context. I wouldn't dare instaflash my MN21 with 3 x series li-ion! Thanks for the precaution anyway!

In general, with regards to the MN61 (li-ion) being brighter than the MN21 (CR123), I wasn't quite expecting it but I'm not that surprised either. If a single li-ion is underdriving a SF 6V LA and double li-ion is middle-ground for 9V LA, then logically triple li-ion is going to overdriving a 12V LA assuming batteries of reasonable capacity that is. I've run the MN61 on 3x17670 before and it was quite white and impressive but got hot pretty quickly. I can imagine two parallel stacks to be even more impressive!

Nugget, do you happen to have 2x18650 with MN21 to challenge the 6xR123 + MN61?


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## nuggett (Nov 15, 2006)

On a fresh pack of these 700mah MP cells from Lighthound, At rest,I measured 12.6v.Under load 11.7 pulling 3.7 amps. Bright light lasted 18 minutes before dimming rapidly. cells and light were a bit warm but not near as hot as the MN21/123 stock setup.
When done,I measured 10.9volts resting, 10-8 volts and dropping rapidly under load, and 3.7 draw. I am pleased with this setup and probably can expect a full 20 minutes on the blue 800 mah cells.


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## js (Nov 15, 2006)

nuggett,

Holy current-draw, Batman!!!

Your current numbers suprise me. They seem too high. In addition, if the lamp draws 3.7 amps at 11.7 volts, it can't also be drawing 3.7 amps at 10 to 8 volts. Something is wrong there.

Please don't understand this is any kind of attack on you! It just doesn't add up. If it really were this high of an over drive, it would totally blow away the MN21. 11.7 volts times 3.7 amps is *43 watts!!!*. And over-driven watts at that, so we're talking like 35 or 37 lumens/watt equates to 1591 bulb-lumens which would mean 1034 lumens out the front of the light, which would be a 64 percent increase over the MN21 output. The pictures and your description of how things are don't dovetail with that, do they?

Is there any chance these measurements could be in error?


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## nuggett (Nov 15, 2006)

Yes, they were done with my Fluke 337 meter, and the jumper may not have been contacting well. I dont think the meter was made for this kind of work.
:laughing: :shrug: :shrug:
After the volts measurement, I had to reconfigure to measure amps, so it wasnt done together.


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## js (Nov 16, 2006)

nuggett,

Getting current and voltage measurements for the SF MN series lamps is actually suprisingly difficult. Even just clipping on to the coil springs can be problematic. And if you are doing the current measurement with a DMM with long test leads, you are unlikely to get an accurate reading. And then there is the question of connecting to the MB20 battery holder. It's tricky (and painful) to do.


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## LED61 (Nov 16, 2006)

JS, this will probably be undoable but have you checked the Tenergy RCR´s spec sheet here ? http://batteryjunction.com/rc390reliba.html

I know you are considering only the unprotected lighthound cells for this setup but:

1) The cells are not unrecommended for bulbs that can handle more than 7.2 V, such as the MN61

2) The cells apparently detect overcurrent and shutdown above 3 amps

3) Could we have more acceptable voltage levels for the MN61 as these have lower operating voltages, and

4) They are protected cells below 2.6 -2.5 volts so we would not have to worry about over discharge ?


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## js (Nov 16, 2006)

LED61,

It all sounds good--points 2, 3, and 4 are definite pluses. Should be worth looking into. My only concern is that the protection cicuit in the cells will see a cold MN61 filament as a short circuit and will not allow the cell to engage. That has always been the problem with using conventional Li-ion protection circuits with high power incans. The only way to know is to try. Or to find out from someone who already has tried.

On another note, I should point out that *WE CAN ALSO EXPLORE USING THE MN60*. It will run for longer and still be bright and white, and will definitely have a longer life than the MN61. Exactly how everything will be precisely still is up for determination, but I can tell you that the MN60 is a safer, longer-lived choice, even if the power and output are lower. It will still be brighter than the MN20--and that's plenty bright for most of us.


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## LED61 (Nov 16, 2006)

I´ll volunteer to try the MN60 and MN61 with the Tenergy´s. Milky has offered my an MN60 for sale and I can order an MN61 and the cells and charger. There is a 12-16 ms delay in overcurrent detection maybe this will help the cold filament issue you think?
Oh and Jim I hope there is not any real danger in doing this, just wanted to ask you what you think the worst case scenario could be?


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## js (Nov 16, 2006)

LED61,,

No. Not really. No danger as long as you are careful to ensure all Li-ion's are at the same state of charge and do not over-discharge as I mentioned earlier.

And as protected Li-ion's do this automatically, they are even safer--especially if they don't work at all. LOL!

And it looks as if you won't blow your MN61 on overvoltage, so it's highly unlikely that you'll blow an MN60. But statistically, an instaflash or an explosion is possible with almost any high pressure lamp at almost any drive level. But the worst that would happen here is you will spoil your turbo head.

Still . . . to repeat . . . Li-ion ARE NOT inherently safe. Be careful to treat them well and follow the guidelines for use. Especailly dangerous is overcharging them. That's why it is recommended to take them all out of the MB20 holder and charge them separately, or all in parallel, to ensure that in a series stack, one isn't high with two low. i.e. instead of 4.1, 4.1 and 4.1, you could have 4.4, 4.0, 3.9, for example, or even worse. Both cases add up to the same voltage, but in the one case you are safe, whereas in the other you are approaching a very dangerous voltage for the high li-ion cell.

Anyway, no way to know if the protection circuit will play nice or not. We shall see.


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## Flea Bag (Nov 16, 2006)

FWIW, the MN60 on 3x17670 (AW Protected 1600mAh, M4 body, + 2 extenders) runs a very strong 55 minutes till protection shuts it down. The test was boken into four segments to allow the setup to cool down so as to avoid damaging the cells.

The MN60 doesn't require much from the li-ions as the cells come off the charger warm with the cells reading 2.93V, 3.10V and 3.12V in order of position in the flashlight with the 2.93V cell closest to the hot front end. After an hour or two of rest, the cells read 3.13V, 3.34V and 3.37V respectively. I apologies for I lack the ability to measure current and voltages under load.

The cells all started with identical voltages of 4.20V slightly warm from charging so if starting voltage was at a more healthy 4.10V then I guess the 55 minute figure should be reduced a bit. 

Take note though that perceived colour temperature stayed remarkably consistant throughout the run. I say perceived because I forgot I had the A2 to use as a benchmark for comparison.  Fortunately, I did have an MN16 + 2 x 17670 running simultaneously. Even in the last 10 seconds of shutdown, the MN60 setup was only very slightly more yellow than the MN16 setup which was running strongly at half battery life and still overdriven compared to running on primaries.

With the differences in voltage sag and current, it'll be interesting to see how a 3s2p setup compares in terms of runtime and tint.


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## js (Nov 17, 2006)

OK.

www.batteryspace.com sells a holder that will accomodate a 123A cell. Plus a company called Memory Protection Devices (www.batteryholders.com) has holders for 123A sized cells. So for those who want to create a 6p1s holder, you can just order six of the holders from battery space and solder or crimp all of the red wires togetherm and solder or crimp all of the black wires together, then just clip onto the solder or crimp points with the charging cable alligator clips.

Or if there is enough interest, we could organize a group buy and get MPD to make us up a 6p1s holder professionally. We'd need at least 30 people interested to make it worth while I would guess.

Anyway, so there it is.

OH, and keyelco.com has battery holders as well. Cat No. 1029, page 19 of the Keystone catelog. Not sure what the relation is between them. Not sure of price either.


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## js (Dec 16, 2006)

nuggett,

How is your rechargeable M6 setup w/MN61 holding up? Lamp still nice and white and bright? Everything OK? How much use has this setup seen so far? Anything to report?


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## nuggett (Dec 16, 2006)

Everything is running fine. I have been running 6 new MP cells and am still on the orginal bulb. About 6 charges so far. I might have one slightly defective or weak battery. Its charged voltage is slightly lower than the others, works fine though.
I really like it except for the runtime.. about 17 min.


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## LED61 (Dec 18, 2006)

Hi Nuggett, I've been reading along this thread again and all of JS instruction and there is still one thing bugging me and preventing me from jumping in to test the MN61 on Tenergy's RCR's. They hold lower operating voltage than your lighthounds, I'll have 9V under load vrs your 10.5-11.1. Jim was worried of your current draw which you initially pointed to be over 3 amps. I'm worried your wiring inside your MB20 might degrade slowly? can we find out for sure what kind of amp flow you've got there? I'd like Jim to chip in on this also (and I'm worried about my current flow with lower voltage).


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## js (Dec 18, 2006)

LED61,

The MB20 battery holder will take 5 amps without trouble, so that's not an issue! The only issue I can see is that the lamp life of the overdriven MN61 may be rather short--sub 10 hours kind of thing. Or it may not. There's no way to tell for sure right now.


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## LED61 (Dec 18, 2006)

OK Jim, thanks for clearing that up for me on the MB20, what about the discharge rate on the RCR´s if Nugget is reporting 17 min runtime that´s way too steep discharge rate for the li ions or not ?


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## js (Dec 18, 2006)

LED61,

That's pretty darn steep! Yeah. Cause for concern. I think 2C (30 min) is the recommended max. So this means it's important to keep tabs on the individual voltages of all the cells, both at start of run, and at end of run and before charging. What is likely to happen is that the weakest cell will go downhill a lot faster than the others, and get over-discharged, and then vent when charged, or have some other type of failure.

Point is, keep an eye on things if you run this setup.


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## nuggett (Dec 18, 2006)

Those issues are above my paygrade. But the MN21 pulls 5 amps, so there ought to no concerns.


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## LED61 (Dec 18, 2006)

Oh OK so the 3+ amps figure is the total current for the bulb then, divided by the two parallel stacks you have between 1.5 and 2 amps for each stack?


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## js (Dec 18, 2006)

LED61,

There are indeed two parallel stacks that share the total current. But 17 minutes is 17 minutes, no matter what the current and delivered capacity are. So 17 minutes is >3C discharge. And 3C is usually considered the max for most Li-ion. Doesn't mean you can't do it--just means you should be careful and aware.


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## nuggett (Dec 18, 2006)

I wonder how AWs new high current protected RCR123 cells would fare with this setup?


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## LED61 (Jan 17, 2007)

I've just bought an MN61 and will buy AW's new protected RCR's and report back. It'll be a while before I get all this down here though. Meanwhile, have you guys any other thoughts regarding Nuggett's running this lamp with this setup ? I'm asking because I'm just curious as to why so much current draw through each parallel stack to make this bulb so dogone bright!!


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## js (Jan 26, 2007)

LED61,

We don't actually know the current draw of the MN61 on this setup. The answer nuggett got (3.7 amps) is probably too high. As I mentioned, it's very difficult to get the current draw for these lamps for various reasons. But, even if we take the 3.7 amps at face value, that's less than 1.9 amps through each stack, so it's actually less of a current draw than with 123 primaries and the MN21. However, it is A LOT HIGHER VOLTAGE, and on top of that, the MN61 is way more over-driven than the MN21. Really, it's probably too over-driven to be all that practical, but only time will tell, and more testing.

This is why I suggested that someone try out the *MN60*. It looks like it will have to be me.

But either way, this is a pretty darn cool setup if you ask me. A total drop-in solution. Just get a new LA and some R123 cells and a Li-ion charger and you're good to go.

I may make a new thread on this whole deal if I end up getting some R123's and the MN61 and MN60 lamps for myself. By now I expected that at least a few more people would be trying this out. But, thanks guys, to those who have done some testing with this setup. Especially thanks to nuggett for those beamshots and other research and posts!


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## cy (Jan 26, 2007)

that would just be outstanding! 

drop-in solution 6x R123 high current and M4 bulb. so aprox. $65 costs. I'm game to try! 

be nice if we could come up with a five-mega quality pack that would accept 2x 18650 bare/high current protected for direct drive NM21. 

better yet would be a five maga quality pack to accept 3x 17670 high current with a willie hunt PWM board. no solder packs, solid connection all the way. if a cell blows, not a big deal. 

this setup would make a modular li-ion M6R pack. 

stock surefire M6 pack is 92mm. using 17670 would give 25 mm to work with. fivemega works regularly with less room. using willie hunt regulator would be a proven solution if combine with a fivemega style quality pack.

does anyone have 3x pila sized 17670 to test for high current draw?

I'm not up for doing a run, but there's got to be several other folks willing.


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## LED61 (Jan 27, 2007)

I chickened out of testing these lamps on unprotected cells to tell you the truth, and we originally suspected Nuggets current draw might be even higher than that because he reported 17 in runtime or something over 3C IIRC. Now that AW's got these new cells I'm willing to do some experimenting. I'll try briefly on the MN61 and might even get an MN60.


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## dizzy (Jan 27, 2007)

LED61 said:


> ......and might even get an MN60.


It looks like you just did get one. Good job.

js, I just got an MN holder with a 64275ax lamp installed in it to fit the M6 (made by petrev) and was wondering if you had any knowledge about this lamp. It will supposedly work nicely in the HDM6, ......, but was wondering what other options I have with this.


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## LED61 (Jan 27, 2007)

You noticed dizzy, hehe!! yeah, I let Jim down on that test but I'll order some AW's protected to see what it's like. It'll take a while getting all this down here but I'll do it.


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## cy (Jan 29, 2007)

here's a link to AW's new high current R123's. 

he's testing if charging two 3x R123 stacks in loaded stock M6 pack with triton will work.

http://candlepowerforums.com/vb/showthread.php?t=144427&page=4


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## cy (Jan 29, 2007)

AW just successfully charged 6x R123 high current in stock M6 holder with triton. 

http://candlepowerforums.com/vb/showthread.php?t=144427&page=4


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## LED61 (Jan 29, 2007)

Right cy, now the only problem we have with the MN61 is we suspect it is drawing too much current from two stacks and is heavily overdriven.


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## LED61 (Jan 29, 2007)

cy, I need a favor from someone able to use paypal PM incoming.


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## js (Jan 29, 2007)

dizzy,

The 64275. Yes. I built a light for S4MadMan which he ended up calling the X5D, if I remember correctly, which used the 64275 and another 6 volt Osram lamp. One was 35 and the other was 30 watts? I think that's right. And one was a transverse filament and the other was an axial.

Which is the 275? Is that the axial? I hope so, because the transverse filament was wound on a SQUARE form, which is NOT good for flashlights. We want round filaments, axial or transverse.

But, anyway, what I remember about both these lamps is that their efficiency wasn't very high due to lower gas pressure than is normal in SF and WA high pressure xenon lamps. I remember that the X5D wasn't really much brighter than the MC60. i.e. the 30 or 35 watt X5D wasn't much brighter than the 20 watt MC-1160. And that's just crazy.

Of course, you're overdriving the 275 more with 6.8 volts (vs. 6.0 volts), but I don't know, I was never that thrilled with those lamps. But I never saw them at 6.8 volts.

Will it even fit up the bore of the M6 reflector? I guess it must.

Moving on . . .

LED61, you didn't "let me down"!!! Don't talk non-sense man!

cy,

We can definitely charge the MB20 with R123's loaded in it all as a unit. No problem. It's just a 3 series Li-ion charge. The issue is that there is no way to ensure, with unprotected cells, that every cell in a stack has the same voltage. So if one is too low, the others will get over-charged--which can be bad. Plus, that means some could get over-discharged if the light is left on too long at the end of the run.

Honestly, though, if you occasionally (like every two or three runs) check every cell's voltage with a DMM, you're going to be fine and will catch a cell that starts to run away from the others and die an early death.

In any case, as LED61 points out, we need cells that can handle a 3C discharge *IF* we want to use the MN61. Can AW's protected cells do that?

But, whatever, all of these issues can be resolved one way or another--the point is that this is a pretty easy and viable rechargeable M6 solution. The more I think about it the more I like it.


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## LED61 (Jan 29, 2007)

Jim, the max recommended by AW is 2C. I still don't fully comprehend how the bulbs "detect" two stacks and draw more current. I guess that's also how the MN15 gets the extra boost in the M6.


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## js (Jan 30, 2007)

LED61,

The bulb doesn't do any detecting, actually. The bulb is just a resistance. But across that resistance is TWO stacks of cells, or in other words, two voltage sources in parallel. Because they are tied together at the positive and negative terminals, by the laws of electrical circuits, they MUST have the same voltage.

So, anyway, assuming all the cells start at the same voltage and state of charge, and we put a resistance across the two stacks which are tied in parallel, then both of the stacks will start to supply current. If one stack starts to supply MORE current than the other stack, it's voltage will drop, and will cause the OTHER stack to start suppling more current instead, and so on. Thus this is a stable self regulating situation, as long as all the cells are quite similar in capacity and discharge ability. This is why you want to load your MB20 with cells that are all in the same condition, and of the same type.

And yes, this is exactly how the MN15 gets such great runtime in the M6 and has such nice whiteness (due to higher voltage)--simply because the two stacks share the load equally (we hope anyway!).


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## LED61 (Jan 30, 2007)

Ah!! thanks Jim, everytime I learn something new from your posts.


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## js (Jan 30, 2007)

LED61, thanks! You're too kind, though.

Anyway, I've been thinking about something. There are sort of two ways of talking about discharges. In one way, you take the *nominal* capacity of the cell, like, say, 700 mAh, and use that value in multiples to determine what xC is. So, for example, 1C would in this case be 700 mA. 2C would be 1400 mA, or 1.4 amps. And 3C would be 2.1 amps. But, the rub is that if you draw 2.1 amps from 700 mAh Li-ion cells, *you will not get 20 minutes of runtime*. So, it's a "3C" discharge in the sense that the current is three times the nominal capacity, BUT, it's not a 3C discharge in the sense of discharging all of the capacity of the cell in 1/3 of an hour.

Which brings me to the 2nd way of talking about C rates. Just simply in terms of hour multiples and fractions. So, a 2C discharge, by this definition is a 30 minute runtime. And 3C is 20 minutes. And C/10 is a 10 hour discharge. This says nothing exact about the actualy current being drawn. It is in this sense that I said that nuggett's 17 minutes of runtime meant a "3C" draw rate.

The difference comes about due to the loss of energy to the internal resistance of the cell, and thus some of the capacity is wasted. Some cells, like high-rate NiMH cells, have VERY low internal resistance, and thus when you go to twice the current draw, you pretty much get half the runtime, almost exactly. Li-ion cells, on the other hand, perform worse and worse as you draw more and more current, which is due to the higher internal resistance--like 10 to 50 times worse than high rate NiMH cells! So, anyway, you can see that drawing 1.4 amps from a so-called 700 mAh Li-ion cell, will probably NOT give you 30 minutes of runtime. And, in fact drawing 700 mA from the cell will probably not give you 60 minutes of runtime either.

Because, sadly, manufacturers generally come up with that nominal advertised capacity using a *10 hour discharge!*. Which is obviously pretty far from the reality in most cases.

So, you can see that the 17 minutes of runtime that nuggett got driving the MN61 _does not necessarily mean that we are drawing more than the recommended maximum draw rate_. It all depends on what the manufacturer *meant* when they said "3C".

Hmmmmmm. We should find out!


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## bwaites (Jan 30, 2007)

Really, though, if they were at least consistent, meaning that if they said 700Mah and they were all rated at C/10, we could at least develop a scale that would give us a good idea of what was happening.

The problem is that they aren't consistent. Some manufacturers use C/10 discharge, some use .1A discharge, some use what their fairy godmother told them when she took their tooth from under the pillow. (Oops, that's mixing up my mythological figures, it's the TOOTH fairy that takes the teeth!) 

My experience with LiIons is that for each 1C above 1C of increased current, you lose 30-40% off the rated capacity. So if you draw 4.8 amps from a good, unprotected 2400 Mah cell, you don't get 30 minutes of run time, you get around 20 minutes before significant dimming. If you use 3C or 7.2 Amps, you get about 11-13 minutes before significant dimming. 

Since the double stack or rechargeable 700Mah cells essentially gives you 1400Mah to work with, 2.8A draws would give you 20 minutes. 

So if you are drawing 3C or 4.2A, count on well less than 15 minutes, not the expected 20 minutes. I expect that the smaller cells are even less tolerant than my LG 18650's so it might be even less than 10 minutes.

Bill


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## LED61 (Jan 30, 2007)

So basically if we don't get at least 30 minutes runtime we should not run a given setup. Looking at Nugget's beamshots, I can't possibly imagine that MN61 pulling less than 3C. I'm surprised that lamp did not instaflash or explode. Arg! in order for that to be brighter than the MN21.....


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## bwaites (Jan 30, 2007)

Well...Lot's of people, especially the RC guys, are running 3C rates. The problem is that they aren't holding them in their hand, like you are with a flashlight!

The new A123 C sized cells are rated to 100A! But their nominal voltage is 3.3V, and there aren't chargers for them readily available, although you can charge them with a Triton or similar and then stop when they hit 3.8V.

Bill


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## js (Jan 30, 2007)

LED61 said:


> So basically if we don't get at least 30 minutes runtime we should not run a given setup. Looking at Nugget's beamshots, I can't possibly imagine that MN61 pulling less than 3C. I'm surprised that lamp did not instaflash or explode. Arg! in order for that to be brighter than the MN21.....



Actually, the other way around. According to Bill's rule of thumb, 20 minutes of runtime would equate to a safe *2C* draw rate. i.e. the current draw rate is *less than* what the runtime calculated draw rate would indicate.

Clear?

So, this is good news. It means that the MN61 is _probably_ safe to use, even though it is on the edge of the "safe" region. I say this because 20 minutes of runtime would be 2C according to the bwaites rule, and we're talking 17 minutes, BUT, on top of that, since these are smaller cells with probably more internal resistance, it's likely that the 2C draw rate would give LESS than 20 minutes.

Anyway, it can all get rather pedantic talking about all this stuff. To take another angle on things, we would really want to know how hot the cells are at the end of the 17 minute run with the MN61. If they are too hot to hold onto for any length of time, that's bad. If they are simply rather warm, but are able to be held continuously, that's probably OK.

Another indicator would be how they continue to perform with more and more cycles. One of the effects of too high a draw rate is loss of capacity with cycles, so that after, say, 25 cycles, you get only 12 minutes of runtime. That would be a bad sign.

And yet another indicator would be how quickly one or more cells starts to stand out from the pack by becoming weaker faster than the others.

In short, we need the following:

1. Another current draw measurement to verify or gainsay the one nuggett made.

2. A temperature measurement at the end of run, even just via "feel", no temperature probe needed. If you can hold onto the cells for more than several seconds they are less than 160F.

3. Another runtime test after two or three dozen cycles.

and

4. Occasional, but persistant monitoring of each of the individual cell voltages at the end of run. i.e. check and record them every 3rd run or something. And probably same goes for starting voltage if the cells are changed in situ in the MB20 holder.


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## LED61 (Jan 30, 2007)

I just re-read this whole thread to digest how this has evolved, and I'd really like for Nugget to report what has been going on lately. His last report he had runtime down to 17 minutes from 20 minutes initially and suspected a bad cell. We haven't heard from him in a while. Could it be his cells went bad from the high draw rates ? I don't know this MN61 business sounds pretty risky to me mainly because of the turbohead. I kind of like JS idea of the MN60, and will try that for sure. As it turns out I bought one of each but wonder whether I should try the MN61 you all see ? that's what I mean I'm sort of chicken$$$$.

P.S. I had not read JS post before I typed all this sorry Jim if I sound contrarian.


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## js (Jan 30, 2007)

LED61,

No problem! Don't worry about it! I just wanted to reassure you (because you have an MN61 on the way) that it may be OK and safe to use the MN61 and R123's! That's all.

Oh, BTW, I sent out your package yesterday via priority mail. Hope it gets to you in a timely manner.


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## nuggett (Jan 30, 2007)

Hello everybody!
I have about 6 charge cycles so far, mostly short runs. IIRC, the batts on the first 17 min run were just warm to the touch, not hot. I have concerns about the load on the batterys, and perhaps damaging the unprotected cell$. I will give them another continous run soon, measuring voltages and guesstimating temps.


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## js (Jan 30, 2007)

nuggett said:


> Hello everybody!
> I have about 6 charge cycles so far, mostly short runs. IIRC, the batts on the first 17 min run were just warm to the touch, not hot. I have concerns about the load on the batterys, and perhaps damaging the unprotected cell$. I will give them another continous run soon, measuring voltages and guesstimating temps.



"just warm to the touch" is good. Now if they just don't loose runtime over the next 6 or 12 runs, I'd say the draw rate is not too high.


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## cy (Jan 30, 2007)

got NM61 and NM60 enroute...


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## js (Jan 30, 2007)

Guys,

Just looked at SilverFox's Li-ion shootout thread. If you scroll down to the powerizer graph, you can see that they are really doing quite well all the way up to, and including, 2 amps. The Light Hound cells can handle up to 1.5 amps, according to the graph, anyway. But they seem to be holding more or less the same voltage under load at 1.5 amps as the powerizers. However, the powerizers have slightly more capacity under that load than the Light Hounds.

Either cell looks fine, but looking at the SilverFox graphs, I'd lean towards the Powerizers, especially if I were thinking of using the MN61.


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## LED61 (Jan 30, 2007)

Ah!! might be good too Jim if Tom can test the AW new protected 123's. These new 123's are loaded with safety features and are made special for incandescents according to AW. If we could see those perform as good as the Powerizers we would not frown at Nugget's current draw would we. 

I'll tell you what, I'll have AW ship my cells to Tom for testing and then Tom can ship them to me.


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## js (Jan 30, 2007)

LED61,

Yeah! Good idea. I'll twist Tom's arm next time I call him. hehe.


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## SilverFox (Jan 30, 2007)

Hello Jim and Alberto,

No twisting needed... I would be happy to check them out.

Tom


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## cy (Jan 30, 2007)

super cooool.... this is turning into a team effort!!!


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## AW (Jan 31, 2007)

Tom,

You should be receiving couple of my new R123 cells in a few days ( shipped on 26/01 ). Courtesy from someone.

AW


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## SilverFox (Feb 4, 2007)

Hello AW,

The cells have arrived - Thanks Jeff...

The testing is underway.

The cells do have low voltage protection, but seem to keep going under high loads. At 2.5 amps, I am seeing around 7 minutes of run time, but the voltage does drop down and the cell heats up.

I think we are interested in 1.5 amps, right?

I will get a graph up as soon as I can.

Tom


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## nuggett (Feb 4, 2007)

I did another run tonight, a bit differently though. Since I am not quite comfortable doing a straight run, I ran 10 minutes with a 1 minute break, then another 10 minutes. I still had juice for another 2 minutes, after which the pack was unable to sustain a 1 min run without noticable dimming. So I got 22 minutes of light to an eyeballed 50%
Here are the cell volts before and after
batt
1......4.21.........3.68
2......4.32.........3.46
3......4.22.........3.72
4......4.21.........3.65
5......4.32.........3.68
6......4.18.........3.44


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## cy (Feb 4, 2007)

nugget, nice job! 

did you use NM60 or NM61 for your run?


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## nuggett (Feb 5, 2007)

61


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## LED61 (Feb 6, 2007)

Hi guys, I just received my MN61 from Cribbage today. I must say, having never seen one of these lamps, it is awfully robust. It almost looks bigger and sturdier than the MN21. I don´t know, but if this is any indication of what the lamp can take, no wonder Nugget has had great results with his. It should be able to withstand at least the same amount of internal pressures that the MN21 takes. But again, I don´t think I am really qualified to be assertive on this. I cannot try it out yet because I don´t have my R123´s yet.


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## MikeF (Feb 12, 2007)

I received the MN-61 from Surefire today via USPS, and I received 8 additional Powerizer RCR123A 3.6V batteries and another charger last week, so after picking up my son from school, I loaded up the M6 and fired her up. Wow is all I can say! Incredible throw, large hotspot, and very white color. If it last a long time, it will be fantastic! The batteries and charger are the same ones I have been using for my Lion Cub and TW4, so I have suddenly, very simply increased the usefulness of my M6.

Earlier, when I was preparing for the imminent arrival of my HD-M6 with 3200 and 4800(little did I know), I purchased a FM Bi-Pin adapter to use with Phillips 5761 Projection Lamps, which I believe are 30W, 6V lamps. They are a lot less expensive than any of the Surefire Modules, but I am wondering if they would work with the Powerizer RCR123A 3.6V batteries? The MB20 is 3S2P so the 5761 lamps would be heavily overdriven at around 3x3.6=10.8 Volts so would this combo insta-flash and possibly damage the reflector? Any insight would be very appreciated.
Mike


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## LED61 (Feb 12, 2007)

I think that 10.8V would kill the 6V bulb, sounds more like a WA1185 would work better, but even then the current draw would be way too much for the little 6 RCR's. Fivemega has special battery holders and extension tubes for your setup so bigger capacity cells are used for the high current draw. Perhaps some of the more knowledgeable guys in this thread can chime in they all know more than I do, until they do I'd stay away from your trial.


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## js (Feb 13, 2007)

MikeF,

What LED61 said. 3s2p R123's would blow a nominally "6 volt" lamp unless it was very, VERY under-driven at 6 volts.

You could drive an 1185, though, and while LED61 is correct in being concerned with the current draw (about 3.3 amps), each stack would only have to deliver half that, and people have drawn similar currents from R123's here already. If I remember correctly, SilverFox tested the Powerizers at 2.0 amps even (which would be 4.0 amps total--more than the 3.3 amps) and they didn't explode or anything.

Still . . . be careful. Note what I said above about the MN61 and R123 safety.

In any case, I personally feel that the precisely focused and potted SF lamps are worth every penny you pay for them. You probably won't get as nice a beam from an 1185 in a bi-pin holder. Or if you do, it won't *stay* there over time. At least that has been my experience with bi-pin sockets; it's possible that FM's is superior. (That would be just like his stuff!)


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## MikeF (Feb 13, 2007)

Thanks Jim, I used the MN61 and R123 setup this morning, live on air during our newscast with one of the station's meteorologists to show how foggy it was early this morning. It looked like a giant white light saber, as he waved it around in the fog and freezing drizzle before sunrise.

 :naughty: :touche: 

I am looking at the Bi-Pin adapter to be a backup for the two MN-61's that I have. Originally it sounded like the 5761 would be a good choice with the HD-M6, but...


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## LumenHound (Mar 7, 2007)

Tom, how is the testing of the AW high current RCR123's going? Any updates?

Jeff



SilverFox said:


> Hello AW,
> 
> The cells have arrived - Thanks Jeff...
> 
> ...


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## MikeF (Mar 26, 2007)

Does anyone know the voltage and wattage characteristics of the Surefire MN61? I would like to find a G4 equivalent for the Fivemega Bi-Pin MN Lamp assembly to use with M6 with Powerizer 3.7v RCR123 batteries.


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## MikeF (Mar 27, 2007)

Bump


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## js (Mar 27, 2007)

MikeF,

Earlier in this thread you will find my best guesses as to the I-V MN61 characteristics. Post #44 in particular, but also elsewhere.


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## LED61 (Apr 8, 2007)

I wanted to post some info here that is probably relevant to the original title in this thread. I just got through testing the life of an MN21 bulb using Wquiles 7.5V regulated pack similar to JS 6.8V regulated M6-R. In fact, the battery assembly in this pack is the one used in the M6-R and was made originally by JS. Wquiles modified the LVR to 7.5 volt output to beautifully drive the MN20. I was eager to try this pack in the MN21 by severely overdriving it, and after some testing in a used MN21 I tried a new lamp. Initially, the lamp generated a big WOW!. I had been warned by both these gentlemen not to use this pack in the MN21 but decided to do it anyway for grins. After an impressive hour on the new lamp I watched how the glass envelope slowly but surely turned darker and darker on the inside and all the while losing lumens. It went for 28 charges of about 12 minutes each or 5 and a half hours before the filament finally broke. By the end of its life, output out the front end equaled more or less that of an MN20 on fresh batteries. 
In corresponding with JS about this it seems the MN61 is being seriously overdriven pretty much the same if used with RCR's and Jim has always been more optimistic about the MN60 probably being a better performer. We're still waiting for AW cells to test but while the MN61 might work like in Nugget's test, I for one am through overdriving lamps like this not only because of decreased lamp life but also because the lamp loses lumen output fast due to blackening of the glass envelope.


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## LumenHound (Apr 9, 2007)

Tom, how is the testing of the AW high current RCR123's going? Any updates?

Jeff


Quote:
Originally Posted by SilverFox
Hello AW,

The cells have arrived - Thanks Jeff...

The testing is underway.

The cells do have low voltage protection, but seem to keep going under high loads. At 2.5 amps, I am seeing around 7 minutes of run time, but the voltage does drop down and the cell heats up.

I think we are interested in 1.5 amps, right?

I will get a graph up as soon as I can.

Tom 


*Tom, more than a month has gone by since I last posted in this thread. Any updates on the testing?* 

Jeff


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## FlashaholicX (Apr 10, 2007)

A new concept:

What if someone were to rewire the stock M6 battery pack so that it was 3 sets in parallel of 2 cells each in series?

Coupled with RCR123A batteries, we would have the M6-R that we always dreamed of, being able to run both stock lamps and with a mild overdrive for the MN21.

js could you chime in?


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## FlashaholicX (Apr 10, 2007)

To add to my previous post, in the event that you needed to switch back to non-rechargable power, all you would need to do is swap in a fresh battery pack with primaries, just the same as with the JS M6-R pack.


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## FlashaholicX (Apr 10, 2007)

Heck you could even run the MN15 M6 X-LOLA that everyone is so crazy about


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## petrev (Apr 11, 2007)

Hi

I tried a pack made from an old ModaMag kit modified to 2s3p LIR123 and without some extra resistance the MN21 blows very quickly - Added 3xR33|| resistors and no problems with instaflash.





If you can fit some resistance in the modified MB20 or it has enough natural resistance then fine.

Cheers Pete


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## js (Apr 11, 2007)

What petrev said.

I considered this re-wiring a long time ago, and checked discharge graphs and figured out the voltage that would be applied to the MN21 or MN20, and in both cases, it was too high.

But, we've already gotten past that hurdle with the MN60 and MN61 being driven by R123's in the stock MB20.  The voltages are reasonable, although the overdrive on the MN61 is too high for my taste . . . but still . . .

The problem now is that the only R123's which can drive the MN60 well for sure are the Powerizers or the Lighthounds, and both of them are unprotected Li-ion cells, and there are dangers associated with these.

If I can come up with a simple, and reasonably cost-effect 6p holder that will put all 6 R123's in parallel for charging, then I will feel confident in promoting this setup for general use. Until then, I am keeping things somewhat hidden inside other threads (such as this one). However, I think I *will* be able to come up with a reasonably priced 6p holder, and this holder would have interest for many people here on CPF, not just the people who want a rechargeable M6. I've been reluctant to tie up money in a mod project again, and get involved with administering one, but I think I'm about to step into the land of madness once again, especially considering that AWR will probably never deliver any significant fraction of the HD-M6's which were ordered.


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## LED61 (Apr 11, 2007)

Will's pack drives the MN21 at 7.5V, probably a little higher than the RCR's, but as the experts have pointed out maybe what saved me from blowing it was the pack's soft start.


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## js (Apr 11, 2007)

LED61,

Actually, three stacks of two series R123's would start off _*higher than 7.5 volts*_ even at the draw rate of the MN21, and would almost certainly blow it. And yes, no soft start would definitely not help.


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## petrev (Apr 11, 2007)

js said:


> What petrev said.
> 
> I considered this re-wiring a long time ago, and checked discharge graphs and figured out the voltage that would be applied to the MN21 or MN20, and in both cases, it was too high.
> 
> ...



Hi JS

Do you mean a 3p2s holder ? 

Anyway we have recently been discussing balance charging over here. Gets interesting from #55 onwards.

To cut a long story short - balance charging using DN/Tenergy or FMA-Cellpro4s (or 6s) chargers (with or without a Voltcraft charging cradle for individual cells as preferred).

Balance Connection to a pack or carrier can be made using small, 2mm pitch, JST connectors (available in 2,3,4,5+ pin confugurations). I have used a 4way JST 2mm to connect to my M6R-Li(XTN) pack for balance charging - pack is 2p3s configuration hence 4 connections (Neg-node1-node2-Pos)





Also, too small capacity to be useful with M6, but may be worth mentioning for somebody, e-lectronics.net do a 3.0V IC protected RCR123A size cell that uses a custom 4.4V charger.

Cheers Pete


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## js (Apr 11, 2007)

Pete,

No.

I mean a separate, charging battery holder that connects *all six R123's in parallel*. There is no need for a "balancing" charger if you can just remove the cells from the MB20 (which is a 2p3s, and which someone suggested rewiring to a 3s2p) and place them in the 6p holder. They will all, by definition, end up at the same voltage every time.

As for Lux's thread, why would I bother with it? I'd need to come up with a bunch of spacer "cells" in order for them to fit in the holders, which need re-wiring anyway.

I'm talking about a $20 or so (or less) holder that will take 6 R123's and put them all in parallel. Then you just connect whichever freaking charger you want to the outputs, *and there is no need for a balancing charger*. Honestly, that is only useful if you have pre-assembled, packaged series-parallel packs with taps on them. The MB20 is no such thing. We can remove and reinsert cells as many times as we like, without the need for clumsy connectors sticking out, and dangerous tabs offering a short-circuit opportunity.

Or perhaps I'm misunderstanding you here? If so, please accept my apology in advance, and enlighten me on your actual intent.


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## petrev (Apr 11, 2007)

Hi JS

That's OK - I misunderstood you as I thought we were talking about a pack for powering an M6 directly.

As you say a 6p holder is intrinsically balanced and needs no fancy charger - so you are using it to charge the cells and then put them back in the MB20 - OK Now I understand.

Cheers Pete


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## js (Apr 11, 2007)

petrev said:


> Hi JS
> 
> That's OK - I misunderstood you as I thought we were talking about a pack for powering an M6 directly.
> 
> ...



Yes. Exactly. That's it.

Unfortunately, this thread is rapidly becoming rather labrythine and confusing and I fear that because it stops and starts with long periods in between that information is falling by the wayside.

Because, yes, that has been my reservation about this mod. A protected cell will solves this OR a 6p charging holder that will ensure balance. Either way. And as it looks problematic with the protected cells, I'm looking into the holder idea.


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## PaulZR-1 (Sep 6, 2007)

Hi guys,

has anybody tested the RCR´s with the MN60? The runtime and beam should be equal to the MN20 running on normal cr123`s or am I wrong?

Greetz
Paul


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## js (Sep 6, 2007)

PaulZR-1,

No one has yet done this. Not with RCR123's. It has been run on three Pila cells, though, and performs nicely. The Kiu link in this thread is where you can find the report. IIRC, he said it was on a par with the MN20.

I have rechargeable 123's, 6 of them, all I need now is an MN60, and I can test this myself. Next SureFire order I place will probably include an MN60

However, Lumens Factory has come out with a LA for the M6 specifically designed to run from 6 RCR123 Li-ion cells installed into the MB20 M6 battery holder. I should probably also get one of these.

I've just had a lot going on, both within my flashlight hobby/business, and in my regular life, and there are a number of rechargeable M6 solutions either to be soon available or in the offing. So I haven't felt any strong pull towards investigating and reporting on the MN60 / 6 RCR123 configuration.


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## PaulZR-1 (Sep 6, 2007)

Hi,

thanks for your quick answer, I already saw the LA from Lumens Factory, great bulb. But I´m looking for an improved runtime, perhaps the LA HO-M4A will work, too.


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## c0t0d0s0 (Nov 17, 2007)

This thread deserves a  !

I've been running the LF HO-M6R bulb in my M6 using Fivemega's 3x17670 holder with great results, but one can never have enough lumens, right? So I figured I'd give the MN61 a try... I half expected it to instaflash on 3 AW 17670 cells, but that didn't happen. Here's what the runtime is like:







Note, however, the sharp peak in output the first 2 minutes or so: the bulb is initially putting more light than the MN21 on primaries, and throws absolutely gorgeous, very high CCT beam that needs to be seen to be believed :bow: I'd say it's running on borrowed time these 2 minutes though... Also note how the HO-M6R, which is the bulb specifically designed for the voltage range of 3 li-ion cells in series, does not display this peak.

With this in mind, can anyone recommend a li-ion charger with adjustable cutoff voltage? I figure that charging bateries to 4.0...4.1V as opposed to the usual 4.2V will let me extend the lifespan of the bulb in this configuration...


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## js (Nov 17, 2007)

c0t0d0s0,

Wow. Nice work! Thank you so much for posting this great info to this thread!

The Triton has an adjustable charge voltage, but it's only one of two choices, 4.2 or 4.1 final voltage per cell, and it shows as 3.6 or 3.7 * # cells in the display as the nominal charge setting--just so you know.

Interesting to note that the 3 17670 cells running the MN61 beat the Lighthound R123's in the MB20. I wonder what it would be with the Powerizers. Probably similar, maybe 20 minutes of runtime at most.

I also still wonder where the MN60 fits. Probably on a par with the MN20 from what Kiu said, or maybe a bit more output.

As for the "peak", I am wondering if this wasn't a spurious result or artifact due to the lightmeter and the radiation pattern of the two LA. Because you would expect a very similar peak with the LF LA vs. the SF MN61, or even a greater peak I think. Who knows, though. Interesting.

But, in any case, the MN61 on 3 17670's seems like an AWESOME combination! I mean, WOW!, brighter than MN21 in this test and with a 30 minute runtime.

A few questions:

1. Are the AW 17670's protected, and which exact cells are they? Are they new? Are they different than the ones he was offering a year or two ago?

2. What brand of primary CR123A's were you using? They thermally shut down, I see. I ask because some of the off-brands just aren't up to the 2.5 amp draw, and not only thermally shut down but also don't drive the MN21 up to its full potential.

3. Does the FM 17670 holder fit into the M6 body and work just as it is, even though it is significantly shorter than the MB20?


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## c0t0d0s0 (Nov 19, 2007)

js said:


> c0t0d0s0,
> A few questions:
> 
> 1. Are the AW 17670's protected, and which exact cells are they? Are they new? Are they different than the ones he was offering a year or two ago?
> ...




1. I beleive these are the latest style 17670 cells from AW, protected, 1600 mAh, with button tops. Got them from Lighthound a couple of months ago.

2. The MN21 plot was done using Energizer CR123A cells. Yes they went into a thermal shutdown even though the body of the light was submerged into cold water during the test. I also have a plot of MN21 on Tenergy cells - those didn't shutdown, but put out a bit less useful light overall.





3. Yes, the FM holder is a bit short, I had to come up with a spacer and an insulating washer to use it in the M6 body. I posted pictures in the LF HO-M6R thread. Maybe if enough people express interest in 3x17670 solutions for the M6, Fivemega would produce a proper drop-in holder for it? Maybe even with a built-in charger connector with balancing leads?

The "peak" is definitely real. Both tests were done on the same set of cells, initially charged to 4.2V each, and I tried to keep everything as consistent as possible between the tests. Differences in radiation patterns between the 2 LAs could've affected overall readings only, but not the shape of the graphs... It must be caused by something else. 

Here's another comparison, LF EO-M3T vs. SF MN16 on 2 li-ions. Again, the LF bulb doesn't have the peak, while it's right there with the MN16. 





(note that relative output numbers in this plot are not directly comparable to those in the M6 plot, as this test was done under slightly different conditions)

I am wondering if the peak is an indication of a the bulb being driven outside of its specs, and its efficiency increasing in nonlinear manner as the voltage is increased? It would be interesting to plot battery voltage next to overall output of the bulb and see what the relationship is between the 2 as battery discharges, but I don't have a datalogging DMM...

Anyway... Yes it's an awesome combo! I was blown away with the beam. With nearly flat output for 30 minutes, it looks like a good cheaper alternative to a regulated pack. Assuming that the bulb can be reliably overdriven like that, of course. I guess I'll keep using it and see how long it lasts... But I feel that if it didn't instaflash with batteries fully charged to 4.2V, it should be pretty reliable if the cells are undercharged to 4.1V at the expense of a couple of minutes of runtime...

Oh and thanks for the charger recommendation. The Triton is not a balancing charger though?


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## leukos (Nov 19, 2007)

c0t0d0s0 said:


> Anyway... Yes it's an awesome combo! I was blown away with the beam. With nearly flat output for 30 minutes, it looks like a good cheaper alternative to a regulated pack. Assuming that the bulb can be reliably overdriven like that, of course. I guess I'll keep using it and see how long it lasts... But I feel that if it didn't instaflash with batteries fully charged to 4.2V, it should be pretty reliable if the cells are undercharged to 4.1V at the expense of a couple of minutes of runtime...


 
c0t0d0s0,

I imagine the MN60 would have more lamp hours on this set up than the MN61, but if the MN61 lasts reasonably long, I think this could be a really fun setup. So how long on an MN60? 90 minutes perhaps?


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## js (Nov 20, 2007)

c0t0d0s0,

The peak is definitely not due to higher overdrive. That much I knew from the get go. But at first, I was thinking that maybe it was spurious, due to reflector/filament geometry stuff and lightmeter idiosyncrasies and so on.

But, then I took a few minutes to really puzzle it out and *DUH!* I think I have the answer. It's all down to the voltage under load characteristics of Li-ion cells. For example, here are a set of discharge curves at various rates for an LG Chem 18650 cell (I stole this from Tweak, just for the record):






As you can see, the 2C curve (red line) exhibits this peak, but the 1.5C line right above it, does not.

And, this accords with the general rule of thumb for Li-ion: 2C is the highest safe discharge rate for most cells because at this point you really start to see the effect of internal heating of the cell anode and cathode materials. At first, the voltage is dropping like a rock due to the high load, and if all else stayed the same, it would keep on dropping rather quickly, but the high draw rate heats things up, which means greater ion mobility, which means faster transfer, which means greater voltage under load. You REALLY see this at 3C in the above graph, for example.

So, anyway, that's the reason for the peak, I think. It's not anything to do with the filament and how overdriven it is, although the MN61 on 3 Li-ion's certainly IS being overdriven. How much so is still up to question. It's simply due to the 30 minute runtime, vs. something like 45 minutes or 60 minutes.

BUT, enough about the peak.

I'm thrilled that these protected cells will turn on against the MN61. 30 Minutes of brighter than MN21 output! How cool is that?

Oh, a side point: I presume that your relative output above is determined by intensity (lux at 1 meter, CP, that sort of thing?) and if so, a beam with a less intense, but larger hotspot, could well be putting out more lumens, relatively, than would be told by a the relative intensities measured by a lightmeter. And the MN21 has a really nice FAT hotspot: twice as big as the MN20, for example. (Unless you are using a lumens estimater box?)

But, even so, I'm not doubting that the MN61 on 3 17670's is brighter, whiter, and higher total lumens output, than the MN21.

This is indeed a VERY promising combo. It may just be the answer to a lot of peoples prayers, if a FM 3 17670 holder is made that is longer. It all depends on just how overdriven the MN61 is. If it has, say, 10 or 12 hours of life, that's probably acceptable to a lot of people. But if it were 6 hours, that's not. And 15 or more would be best for a $30 LA, of course. Although, one can always use the MN60 or LF LA, right?

Anyway, I'm really excited about this and I'm THRILLED that you took the trouble to post to this thread. Thank you so much!


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## LED61 (Nov 20, 2007)

JS, I'd still like to see your regulated pack become a reality some day soon with the MN21.


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## c0t0d0s0 (Nov 20, 2007)

js,

Thanks for the info. Those discharge graphs really explain the mystery!

More about my testing method: my relative output numbers represent lux readings from a ceiling bounce test performed in a small room with white ceiling, white walls, white floor, white everything. I call it my Integrating Bathroom 

I'm trying to keep my tests as consistent as possible, making sure to always shine the lights into the same spot on the ceiling, and place the lightmeter's sensor in the same exact position. I found that despite its crudeness, this method yields surprisingly repeatable results. It is not too sensitive to shape of the beam either. Floody lights definitely don't score higher in this test, in fact, adding a diffuser to any light always shows some loss.

The MN16/EO-M3T graph was taken using a different light meter, that's why I said the numbers are not directly comparable.

Anyway... yes this combo shows a lot of potential. With 3 bulbs known to work with it (MN61, HO-M6R, MN60), we've got all our needs covered. What's also promising is that with 3 17670 cells one has enough room to design a pack with integrated balancing charger connector, NTC thermistor (for poor man's soft start), or maybe even a real regulator board *hint hint*


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## js (Nov 21, 2007)

c0t0d0s0 said:


> js,
> 
> Thanks for the info. Those discharge graphs really explain the mystery!
> 
> ...



White wall/ceiling bounce eh? NICE! I'm getting the picture that you're doing some really good work here! Bravo! Much appreciated. And yes, I agree, the ceiling/white room bounce test with lightmeter is a great way to approximate an integrating sphere. PaulW was the first person on CPF to use this method and was the first to approximate the conversion from bulb lumens to torch lumens with it. And he turned out to be pretty much spot on when we tested with an IS later on.

As for a regulator with 3 17670's, that's in the works--but with the MN21 not 61. That way you have full regulation over the entire run and can use the native M6 LA.


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## c0t0d0s0 (Nov 21, 2007)

js said:


> As for a regulator with 3 17670's, that's in the works--but with the MN21 not 61. That way you have full regulation over the entire run and can use the native M6 LA.



WHOA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Are you planning to release another version of M6-R pack? I guess it's going to have new electronics, with Willie Hunt's LVR regulators not being available anymore? Will it have softstart feature, like the original M6-R? What about support for MN-20? User-adjustable voltage, maybe? 

Please do tell


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## js (Nov 22, 2007)

Willie Hunt regulators aren't avaiable to the general public, but I can get them from him, provided I'm not just pestering him for a one off order or something. If it's for 30 or 50 regulators, he accomodates me. 

So, yes, softstart, and all that sort of stuff like the original M6-R pack. This one will be called the M6-RL. As for MN20 support, I don't know. There may be a small DIP switch to allow the user to change from 6.8 to 7.5 volts DC equivalent, or back again, but honestly, it's not a design priority. For those who really want a LOLA, the MN16 works great at 6.8 volts--not as bright as MN20, but close. We shall see.

I'm hoping that the protection circuitry in the 17670 cells won't kick in and prevent turn on against a cold MN21. I'm close to bench testing this via the first proto-type, but we just got a new cat, and his "home base" is in the room that has my work bench, and he likes to "help" me or my wife if we're working, so soldering is out of the question right now. Plus, you know, Thanksgiving and all. But soon.

The idea is to have the same company that makes the FM pack make this one, with LVR3 integrated into the top cover of the pack. It's a little bit more complicated though, as the LVR needs a connection to + as well, so there will need to be a conductor down the center somehow. But I'm not all that concerned about the details right now. Mostly, I just want to build the proto-type, with the LVR3I along the side of the pack, and do a proof of concept bench testing of the setup. I have Pila 600S cells right now, but I'll almost certainly get some AW cells to have a real life comparison, ESPECIALLY if the Pila circuitry doesn't want to turn on against the cold filament. Maybe the AW circuitry is better for that? We shall see.


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## c0t0d0s0 (Nov 27, 2007)

Excellent news. Good luck with the project! Looking forward to further developments.


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## brunt_sp (Jan 11, 2008)

So am I reading that 3 X 17670s will give better performance/runtime than the MB20 containing 6 X AW R123As ? or are we just saying that they will be easier to charge ?


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## js (Jan 11, 2008)

brunt_sp,

Right. It looks as if the modded FM pack with 3 17670's driving the MN61 in the M6 gives better performance AND runtime than the MB20 with CR123A's driving the MN21. As for the MB20 with R123's driving the LF lamp, well, that lamp will give more runtime but less brightness than the 3 17670's against the MN61.


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## London Lad (Jan 11, 2008)

This is turning out to be a real interesting thread.


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## brunt_sp (Jan 12, 2008)

js said:


> brunt_sp,
> Right. It looks as if the modded FM pack with 3 17670's driving the MN61 in the M6 gives better performance AND runtime than the MB20 with CR123A's driving the MN21. As for the MB20 with R123's driving the LF lamp, well, that lamp will give more runtime but less brightness than the 3 17670's against the MN61.


Thanks. What about the MB20 fitted with R123s driving the MN61. How would that compare ?


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## js (Jan 14, 2008)

brunt_sp,

I don't know. Given that the runtime is shorter, it would seem that the 3 17670 solution would have better voltage under load, and would thus be brighter. But, check out the earlier posts in this thread. They are all about the R123/MB20/MN61 configuration. BE CAREFUL REGARDING THE CHARGING AND BALANCING OF LI-ION CELLS!


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## brunt_sp (Jan 27, 2008)

brunt_sp said:


> So am I reading that 3 X 17670s will give better performance/runtime than the MB20 containing 6 X AW R123As ? or are we just saying that they will be easier to charge ?


I think I can now partly answer my own question thanks to Mdocod's guide.

6 X RCR123 (MB20) with LF HO-M6R: 23W, 480 - 285 lumen in 30 minutes.
3 X 17670 with LF HO-M6R: 23W, 503 - 336 lumen in 41 minutes.

This indicates that the 17670 option when used with the MN61 will also be brighter and give a reasonable increase in runtime when compared to the MN61 with RCR123s in the MB20.


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## c0t0d0s0 (Feb 15, 2008)

I found that 3 17670 cells provide 30% more runtime than 6 RCR123 cells in MB20. And yeah, they're a lot easier to charge, and safer to use.

Here's a comparison between these 2 combos powering the HO-M6R:







More pictures of my rechargeable setup:











(the spring is a shortened Mag D spring)


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