# Care to make some 2x18650 or 3x18650 C/Z/P compatible tubes?



## Action (Nov 29, 2005)

Anyone here on the list interested in making some nice tubes that allow Surefire C/Z/P heads and tailcaps to be used? I would be interested in getting at least a few 2 x 18650 (protected cell or Pila) and (2) 3 x 18650 (protected cell or Pila) tubes. I understand TranquillityBase is selling similar tubes to fit the e series Surefire line here:

http://candlepowerforums.com/vb/showthread.php?t=97346&page=1&pp=30

But I am interested in maintaining C/Z/P compatibility for both the head and tail. Would someone be interested in offering something like this?


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## Lunarmodule (Nov 29, 2005)

Hello,

Thought I would chime in here because I am desperately seeking a 2x 18650 battery tube (body) that i could use with either a KT2 (C series) or KT4 (M series) Turbo head. If you receive any responses could you please notify me via email or PM? I hope you (we) find something as nice as Tranquility Base's E series tubes.


Thanks,

Steve


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## Action (Nov 29, 2005)

Sure, I believe that there are a number of people that would be very interested in getting a solution like this. Particulary if it were as nice or nearly as nice as TranquillityBase's e series solution...


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## Lunarmodule (Nov 29, 2005)

What i wanted to do was run the Surefire MN21 (M6 HOLA lamp) in a Turbo head with 2x 18650s supplying the power. The other route I tried was posting in this forum about boring out the body of my M4 to fit the pair of LiIons but alas no takers so far. Having a nicely machined dedicated tube would be a better alternative.


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## Action (Nov 29, 2005)

I personally am interested in getting a few 3x tubes to run my ArcMania XX1T Lux V setup for a long, long time in my SRTH and to try out the MN60 in a KT head. The 2x tubes will be for the few 9V heads that I've got left over and a KL3.


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## Lunarmodule (Nov 29, 2005)

Action,

My compliments on a nice selection of components you have! Color me green eyed over the Arcmania module! I'm a huge fan of rechargeable LiIon and want to see more extended runtime conversion applications with Surefire lamps/LEDs. The MN60 is a great lamp! My dream is a marraige between the KT heads and the 2x / 3x 18650 tubes we are seeking. I like extreme runtime and the 18650 is a great cell. Are you aware of the 2400mAh grey LG chemical cell that Battery Space sells? If not you owe yourself to go to their site and take a look. Its my fave 18650. Still hunting for Saphions in that size, might have some in a few weeks.


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## Action (Nov 29, 2005)

I don't have any 18650 cells yet, I'm waiting for the new Pilas. When I do jump on the LiIon bandwagon, I'm going whole hog. 17650's would meet some of my requirements with the use of A19 extenders, but why not add 1mm or so and really increase the capacity?

The Arcmania module is really nice. Its very nearly the equal of the G&P12V lamp assembly output (ostensibly 220 lumens) on the X-12. So far it appears to have really nice runtime @ 700mA, even on just 3 123 cells (it can take up to 5 x 123).


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## Lunarmodule (Nov 29, 2005)

The LG 18650 cells (same size as Pila 168 A) have 2400 mAh capacity (versus Pila's 1800) and sell for a very reasonable $8.50/cell. They are the highest capacity standard size LiIon cells I've yet found. I agree with your thinking. There's a big capacity jump from the diameter increase that makes the fat cells quite desirable for us runtime fanatics. What have you heard on the new Pilas? JSBurly sent me an email telling me there will be new improved ones but I am dying to know technical specifics. Should be a few weeks away.


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## HarryN (Nov 29, 2005)

I have built some 2 x long 18650 tubes in the past with my brother, but they were actually 2 x long x 2 wide (4 total) for a custom side x side project. (6 of these are sitting in my garage waiting for me to finish the current CR2 side x side project for Xmas.)

If you just want round ones with 2 cells in a row, that is usually easier to build as a "basic" model, but the knurling done by Tranquility in that E series build is certainly impressive. The look would likely be different.

Going to the larger dia. Pila cells takes a slightly larger bore, but that might be feasible if the threading works out. If someone wants to point me toward the thread specs for the C3's I can match it up. (note - looks like it uses the same threads as the 6 P)

I will look at the feasibility of both the straight tube and side x side configurations and update this thread in a few weeks. It seems possible and not that different than I am already doing for some other projects.

No need to PM me with interest, I can feel it. You can post it here if you like.


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## Action (Nov 29, 2005)

Lunarmodule, I haven't heard any more than you have on the new Pilas, but I generally like the quality info that I have heard about them a bit more than from other LiIon cells.

HarryN,
That sounds great! I'd be interested in either a double or single cell set (more interested in the singles than the doubles, but I'd be in for trying the doubles). From the info that I have, the thread stuff is the same among all C/Z/P series. So if you have a 6P lying around, the threads are the same as the C or Z series. I know that the 6P can be bored to fit protected 18650 cells, so I don't think that the threads should be affected by the cell width.


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## wquiles (Nov 29, 2005)

HarryN,

Interested. I would also love to see how your 2x2 side x side 18650 tubes/holders look like. Got any pictures?

Will


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## Paul_in_Maryland (Nov 29, 2005)

New Pila flashlights thread. Not new cells, just new flashlights and a new charger.

The latest Pila 150A cells, by the way, are 2000 mAh, not 1800.

The 2400 mAh cells--are they protected or un-?

Side-by-side cell mounting is the way to go. It dramatically trims length, and the resulting form factor is easy to hold, pocket, and store.


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## wquiles (Nov 29, 2005)

The LG 18650 cells 2400mAH cells are most certainly NOT protected. I have a few so I know first hand.

Will


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## Action (Nov 29, 2005)

But with side-by-side mounting, I believe that you do not get the voltage that you would get in end-to-end mounting. So for items that require double current or longer runtime with a lower voltage, the double would work great (say 4 x 18650 double would be a super long lasting solution for regulated lights), but for things that need ~12V or so would require 6 x 18650 double, which would be pretty bulky but have super runtimes.

Do I have this right, or am I missing something?

I'm not going to run any unprotected rechargeable LiIon cells in my lights, I don't trust myself...


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## wquiles (Nov 29, 2005)

Action said:


> Do I have this right, or am I missing something?



Depends on what converter you are using and if you are driving LED's vs. incandecent lights. For incandecent, you want a voltage close enough so that you drive the bulb properly but not insta-flash it.

For LED's, and when using drivers (not Direct Drive), the way I look at these "situations" is that I look at batteries as pure energy storage devices with certain available power, when figure out what converter to use depending on how many LED's and whether these (assuming more than one) will be wired in series or parallel.

For LED's, you can use a downconverter (think nFlex or Downboy) or an upconverter (think Fatman or Badboy). If you use an upconverter, then having the cells side-by-side in parrallel is not necesarily a problem 

Will


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## gadget_lover (Nov 29, 2005)

And don't forget, side by side is a PHYSICAL configuration, not an electrical configuration. The wiring can put two cells in series while they are side by side, at 90 degrees, etc.


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## HarryN (Nov 29, 2005)

Gadget Lover is correct. 

Examples
- the CR2 side x side I am building is physically parallel, but electrically in series. 
- It is possible to build a side x side electrically in parallel (of course) but it would required a reverse protection diode on each bank, meaning now it needs a PCB - a bit fancier and probably longer.

I think the easiest configuration to actually build would be the side x side in series, and have the on / off switch on the same end as the head (instead of the normal back end position) Not sure if that is an acceptable configuration or not.

In a 2 x pila version, that would be roughly the same length as you have now, but of course larger body, and the same results you obtain with any 2 x series pila setup. Not sure if that is an acceptable configuration or not.

In a 4 x Pila version, the body length would roughly double, and you would obtain similar results as any other 4 x series Pila voltage / current results.

I was not planning to offer this as a regulated setup, just a body for the SF setup, although my own light planned for this body is regulated. Not sure that that setup makes sense for this project though - adds real length and cost to pull that one off.

I don't have a 6 P ( I make my own lights) but maybe I can borrow one from someone.

I will gather some more info on the total package requirements for this, including how many amps are needing to go through this thing for various configs. Does anyone expect more than 2 - 3 amps continuous ?


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## sflate (Nov 29, 2005)

Any chance you can make a 4AA (2x2) version? I'd buy those in a second.


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## brightnorm (Nov 29, 2005)

Lunarmodule said:


> The LG 18650 cells (same size as Pila 168 A) have 2400 mAh capacity (versus Pila's 1800)...What have you heard on the new Pilas? JSBurly sent me an email telling me there will be new improved ones but I am dying to know technical specifics. Should be a few weeks away.


The pila 168As have been at 2000 mAh for at least 6 months or longer though there are still plenty of 1800 mAh cells around. The new improved ones might be 2400mAh, though that's just a guess.

Brightnorm


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## Lunarmodule (Nov 29, 2005)

HarryN,

What I envision is different from what Action is seeking. What I was looking to do is in essence hybridize a Surefire M4 and M6 to use a power solution that neither one can. The current requirements for my design are higher, exactly 4.9 Amps @ 6.1V. 

What I want to do have a battery tube made about the same size as the SF M4 to allow 2x 18650 cells to be together in series. Then have this threaded to mate with the SF Turbo heads (M4, M6 etc) to run (primarily) the 500+ lumen MN21 6.1V lamp assembly. The side by side orientation you described is very interesting indeed. I also plan to incorporate one of Andrew Wynn Rouse's LDO driver circuits (fits on the tip of a finger) to provide a regulated feed to the lamp assembly. 

This comparison chart gives an indication of the relative dimensions of the M4 and M6. My first thought was to have an M4 body bored out to fit the 18650s but have not found a machinist willing to try it and there is some question of whether there is enough wall thickness. So the other solution is to have a dedicated battery tube fabricated to fit the SF KT Turbo heads. The combination of 2x 18650s in series is a great power solution to run the MN21 lamp and would provide huge runtime for an LED head as well. 

I'd love to see some pics of the pieces you already made. From what I understand Action is wanting the same type of battery tube but instead mate with the more universal C/Z/P series, whereas I am looking for M series compatibility.

In any case, thank you very much for your input here! Its interesting and great to see folks pooling creative ideas. I just wish I had the fabrication skills to make up the things I dream up


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## Lunarmodule (Nov 29, 2005)

brightnorm said:


> The pila 168As have been at 2000 mAh for at least 6 months or longer though there are still plenty of 1800 mAh cells around. The new improved ones might be 2400mAh, though that's just a guess.
> 
> Brightnorm



Thank you Brightnorm!! I must have some OLD 168A's, cause mine are all 1800s. I am very eager to find out about the new design. I've been using the LG cells for awhile and have high praises for them. Forever runtime in my HD45. Thats primarily why I want to have this batt tube, to exploit the reserves of the 18650 cell


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## HarryN (Nov 30, 2005)

sflate - can you describe your desired setup slightly more - as in exactly how you would be using it ? Which tail, head, approx current and voltage ? That would help a lot.

Lunar - It sounds like you are sort of after the equivalent of the MR-6 project in 18650, with regulation ? The circuit you mentioned may or may not be the best one for that project, but I will discuss it with Andrew, as well as others. In any event, the body tube needs to be engineered up front to accomdate the electronics, or it likely will not fit, no matter how small. Believe me, I have gone through a lot to fit some controls and optics into a small CR2 light.

Action - I actually have a voltage regulator in my cabinet that can take the 4 x 18650s Vin and Vout 12 V @ 2 + amps - and it fits in the existing body. Gee, I wonder why I bought that ? ha ha BTW - it is 30 Watts MAX.


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## sflate (Nov 30, 2005)

HarryN said:


> sflate - can you describe your desired setup slightly more - as in exactly how you would be using it ? Which tail, head, approx current and voltage ? That would help a lot.



I sent you a PM with more detail, but I'm basically looking for a 4AA (aluminum) in the smallest size possible that I can put in an overdriven LuxIII. If it could be done with a surefire E-series head/tail, that would be even better. 4AA would be in series (4.8V with NiMH) so I could either run an nFlex/bbFlex or FLuPIC in it. Think of an aluminum UKE 4AA sized light.


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## Action (Nov 30, 2005)

HarryN said:


> Action - I actually have a voltage regulator in my cabinet that can take the 4 x 18650s Vin and Vout 12 V @ 2 + amps - and it fits in the existing body. Gee, I wonder why I bought that ? ha ha BTW - it is 30 Watts MAX.



Wow! Would you happen to know what the max wattage of the MN60 or the MN61 happens to be? This sounds just about perfect!


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## HarryN (Nov 30, 2005)

Before everyone gets toooo excited, I should put some reality into this as far as the amount of work involved. The voltage regulator I have took forever to find (due to size / spec constraints), but is fully protected. It just barely fits, and it costs around $ 70 / each in moderate volumes. (not wired in, no adapters, just plain "direct from the manufacturer costs) It is a full buck / boost setup, so quite a bit more efficient than an LDO in most cases.

I need to see if I can find a similar one which will drive 6 V ish setups.

The bodies I have look a bit plain, but were made for me so they met my initial needs. They can be made fancier of course. My brother made them on his fairly large manual mill, using some custom tooling I bought (about $250) , and it takes him almost an entire day to make each one. I pay him $ 25 / hr for his work.

Before we even have the "other necessary parts", we are fast approaching $300. With some volume (say 50 of these) , I probably can have it made for a bit less, but still, definitely in the $ 200 or so range.

Still interested ?


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## Action (Nov 30, 2005)

Do you have an pictures of the bodies and the regulator puck? I'm having some difficulties in figuring out how all this fits together and looks... A regulated 12V setup is something that is extremely interesting, particularly with either a 6 x 18650 or a 4 x 18650. My Lux setup is already regulated, so I'm just looking for a tube that can deliver at least 6.5V with at least 3 x 18650 to get the really extended runtime I'm looking for.


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## HarryN (Nov 30, 2005)

Hi Action - I don't have a picture - sorry for not making that clear before. I will try to find someone with dig camera to take a pic soon.

The tube, is really more of an oval with two bores. You can get a general idea of the concept if you look at my 2 x CR2 light in the home made section. That is essentially a "shrink" version of the double bored 18650 design. The holes shown in that light are 15.6 mm, vs the nearly 20mm required for a Pila cell (the dia of Pilas are larger than a "normal" 18650)

From my perspective, it is not so easy to buy just the "tube" and end up with a working setup. There are a number of custom parts required to adapt it to a head. I have not fabricated these yet, which is why the project is not finished. I have a couple of grand in it so far. I need to sell some of these smaller lights first to free up some cash for the bigger project - unless you want to help fund this project up front.

I had an idea this morning of how to deal with your desire to have one "tube" run either the higher power incan heads or the Lux V setups. The more info you can post on the voltage / current / mechanical interfaces (size, thread) for the desired heads and tail switches, the better I can work out an integration scheme. Not sure if the package would be an arcmania board or not, but a regulated Lux V is very realistic.

This is not a 5 minute project. Even with the tubes I have, it will take a few months to work through my existing project commitments and produce a deliverable setup. I have been fooling with it now for quite a while.


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## HarryN (Nov 30, 2005)

I took a quick look at the M4 specs

MN 60 - approx 1 hr run time
MN 61 - approx 20 min run time

Based on using 4 x SF CR123s.

Using the run time charts from Silverfox in the battery section, that "looks" like the MN 60 pulls about 1 amp, and the 61 pulls about 2 amps @ 10 ish volts (4 x 123s with sag)

I will dig around for more info.


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## Action (Nov 30, 2005)

I guess that I need to be a bit clearer about what specific items I am looking for as well...

First, if regulation is available for a 12V light, then I am interested in something that can have either a 4 x 18650 Pila or a 6 x 18650 Pila. This would primarily be to run either an MN60 or MN61 bulb in a SRTH, T, or KT series Surefire head. This is purely a thread compatible C/Z/P setup from the head perspective. I'm not sure how the tailcap would work with a double or how switching would be handled. For a Surefire head compatible body with switch and 12V regulation, I would be willing to spend some $$$. This would be 2-3 units for me, maybe not all in one pop as I'm not exactly rolling in the dough...

Second, for my LED needs, I don't need any regulation. My wants in this area are much simpler. A 2 x 18650 Pila or 3 X 18650 Pila tube with Surefire head compatibility and either an integrated switch or Surefire tailswitch compatibility would be needed. A double is not terribly important in this application and if it added a bunch of cost, it may price me out of the market as the first application is more important to me.

Do you have a link for your other lights?


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## HarryN (Nov 30, 2005)

Hi Action - Your inputs are good and I get it on the models, I just have mostly worked with the LED lights, so I need to come up to speed on the incan details. Regulated designs need specific wattage / current / voltage goals or everything can go "puff". 12 volts regulated is substantially more voltge than your M60 / 61s are used to getting with 4 x 123s.

I also do not have any "power incans" so I will need to obtain some heads / tailcaps to take measurements. The SF site obviously does not provide this info, so I need to find some incan experts to help guide me.

My original plan with this larger body was to make entirely custom heads to go along with the body, but your idea of making it accept SF heads is interesting.

The CR2 link is https://www.candlepowerforums.com/threads/91460&page=2&pp=30 There are pics in the first and last post. (as of today)

Lunar Module - I think your needs can fit into this body concept as well, so don't run off just yet. I need to gather some more info. Not sure if I can provide 5 amps regulated or not. How confident are you that your 2 x 18650 setup will work in an unregulated mode ?


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## Action (Nov 30, 2005)

HarryN said:


> Hi Action - Your inputs are good and I get it on the models, I just have mostly worked with the LED lights, so I need to come up to speed on the incan details. Regulated designs need specific wattage / current / voltage goals or everything can go "puff". 12 volts regulated is substantially more voltge than your M60 / 61s are used to getting with 4 x 123s.


Maybe I'm off here, but doesn't 3 x 123 = 9V and 4 x 123 = 12V? The 9P (a 3 x 123 setup) uses a 9V bulb. The M4 (a 4 x 123 setup) uses a 12V bulb (the MN 60 or MN61). A number of the MN series bulbs will fit into SRTH, T, & KT series heads (I believe that the MN15 & MN16, along with the N2 & very rare N62 for 9V applications ; for 12V applications I believe that the MN60 & MN61 are it). A regulated 12V assembly using the MN61 lamp (350 lumens!) would be pretty awesome, although the heat would likely overwhelm the minimal mass of a SRTH, it would probably work with a KT head or another relatively massive head OK, so long as it was not a shock isolated head. A 4 x 18650 Pila without regulation would definitely flash an MN60 bulb, and these bulb assemblies are not very cheap. So without regulation, I would want 3 x 18650 Pilas for the incandescent assemblies, but would likely have to charge and let the Pilas sit for a week or so before I could use them. Even then, I would be a little hesitant as the bulb assemblies are $20+ each...


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## HarryN (Nov 30, 2005)

3 x 123 = 9 volts - sort of.

Take a look at the plots of the 123 comparisons by silverfox in the battery section. When there is no load, the 123 is at approx 3.3 V. The voltage drops as the load increases, down to approx 2.5 V under heavy loads. Over the life of the cell, it drops further. When it is cold, it drops more.

For a lamp that drains a set of 123s in an hour, I used the charts and estimate it is pulling around 1 amp.

For a lamp like the M6 uses which drains a set of cells in < 20 minutes, it appears that it is pulling something like 2.5 - 3 amps. This actually exceeds the ability of the cells to deliver, which is why the M6-R is so popular. It can actually deliver the needed power in a regulated way. It is actually quite an impressive setup, well engineered, and well implemented. If I owned an M6, I would buy at least one.

SF and other lamp makers know this occurs, so they design the lamps based on "reality" and sell the lamps based on "what the customer expects the voltage to be - 12 volts or whatever".

Conventional hot wire light builds are done by adding up cells and lamps until you achieve a balance of brightness, run time, and bulb life. Quite an interesting feat.

In a simple PWM or LDO type circuit, the current flow is "slowed" to keep the lamp in regulation. This works if your V bat is relatively close to the voltage requirements of the lamp.

If the V battery pack is substantially different, then you need to either "boost up" the voltage, or reduce it "buck" it down. Through the magic of electronics, our EE friends have figured out how to essentially "take in watts at voltage x" and convert them to "watts out at voltage y". Similar things are done on most LED lights. (except they regulate current instead of voltage)

This handy but slightly expensive concept allows one to either purchase (in my case) or build a regulator that can take in whatever your batteries have, and deliver what your bulb needs, within limits. The catch is that you now need to actually know what the bulb really needs, and design for it. Space is also occupied. Done properly, it can substantially extend run time, or allow bulb / battery combinations that otherwise would not work. It also allows you to use "hot off the charger" cells.

So the bottom line is, if I can get the right regulator, it largely does not matter what cell voltage you have. I have a 12 volt setup which can handle 2 + amps (not tested to this level yet). I am looking for a 6 volt one for Lunar, which can handle his 5 amp need - a little harder to find.

Hope that helps.


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## jtice (Nov 30, 2005)

I would be VERY interested in a 2x2 setup for the e series stuff. :rock:
a 2x2 AA version would rock also


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## gl22man (Dec 1, 2005)

i also would like a nice 2x18650 setup for my kl6 head and a surefire clickie tailcap..
Mike........


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## HarryN (Dec 1, 2005)

I can see that I need to find someone willing to loan me a C and E series light for a month or so to get measurements and tests some ideas. Ideally, ones which are working, but a bit worn so I don't accidentallly scratch a perfect one.

Here is what I am envisioning for the pure "body / tube only" versions. Just for reference, below are some pics of a proto CR2 side x side. On this light, the light and switch are on the "front" and the 2 cells load from the back (in opposite directions) into the back. The tailcap on this light is then screwed shut (with a dime), and has a small PCB with springs to connect the CR2 cells in series. While I wish there was a way around this, on a light this small, it was the only way I could find to make the walls thin and make it water tight.

For reference, the body is 19mm thick (3/4 inch) x 36mm wide (1.42 in) for a cell which is 15.6mm dia. I would probably use the same OD for the AA lights. The length for a 2 x 2 AA version would end up approximately the length of 2 AA cells in series, plus 19 - 25mm (nominal 3/4 - 1 inch)

The front end plate would accomodate the E series head interface. The head would be unscrewed to load cells into one bore of the body. I would need to do some checking to see if an adapter could be made to fit a C series head.

The rear end plate would accomodate the switch interface, and the switch would be unscrewed to allow cells to load from the back into the other bore. If there is not room, then worst case, you would need to remove the back plate to load the cells.

2 x 18650

I am still thinking about the 2 x 18650 application. I can see how it works in series for the incan bulbs, but I am pretty sure that the SF KL4 / KL5 heads contain a "boost only" circuit, which means that the voltage would be too high for those heads. I might be able to make a special tailcap which allowed the cells to be in parallel, and contain a reverse protection diode to prevent accidental cell reversal.

The 2 x 18650 versions would be similar, except to accommodate the larger Pila cells, the bore is more like 20mm. 

Both the 2 x 2 AA version, and the 1 x 1 18650 version would be "tube and interface plates only" and it would be up to the end user to make an intelligent decision about which flashlight head is the right one to use.

All of this is subject to things actually fitting of course.

For the 2 x 2 x 18650 version in series, I don't see any heads / bulbs or LED combinations where regulation is not going to be needed, or at least be a strong benefit. For this reason, the "front" of the "tube" would have a space for a regulation circuit.

For incan / SF heads, I have a pretty good 12 V constant voltage regulator "rated" for 2.5 amps which might work for some lamps, especially if the voltage is trimmed down a bit. I also have access to a 5 - 5.2 volt version in 5 amps which is close to the actual voltage fed to many 2 x 123 high power lamps. I am trying to find one in something closer to 5.5 V range. 

KL4/ 5 - I suppose in theory, you could have a 5 V regulator feeding a KL4 / 5 head, but the efficiency would be rather low. (10 % lost in each regulator)

For other LED applications, I will need to work out a complete head, as this is a more complex interface, and there is really not much standard out there that would make sense. That has always been the plan anyway.

Here are the pictures so that you do not need to go searching. These are protos, but you get the general idea.


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## wquiles (Dec 1, 2005)

HarryN,

If you PM me your physical address, I will loan you a 6P body and a McGizmo E series body so that you can measure & test on them.

Would you also need the heads/tailcaps or just the bodies?

Will


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## Action (Dec 1, 2005)

HarryN,
I see what you mean about the voltage drop. I had not considered that as part of the design equation. Given that the voltage drop is not instantaneous, my hypothesis is that its not terribly likely that a 12V bulb would flash with a voltage approaching 12V, but would likely experience a shorter lifespan. How much is unknown and would be interesting to know, but I'm not going to volunteer to fund that study the way that these bulbs cost!  

About the design... I'm guessing that you will have some sort of adapter setup to fit a head to this battery tube and that the adapter setup will have to include a switch of some sort and some regulation. I bet that at least a dual level switch will be on many people's minds...

Looking at this, it makes me wonder if a triple would actually be a better design. A triple would be more tube-like to hold, easier to machine some checking or knurling, and would likely be simpler to neck-down to attach the C/Z/P round head fittings. I know that many want a 2 x 18650 setup, but if regulation is used, why not have either a 3 x 18650 in a tube format (same length and probably not much bigger in the hand) for longer runtimes. Then double the tube length to get a 6 x 18650 for those that really want longer runtimes or want to emulate the M6. With this type of setup, changing the sandwich/adapter that would neck the battery holder down to the headsize would be the only requirement to use the holder in multiple different ways. The machining would also probably be a whole lot easier as a simple tube with appropriate boring for 3 x 18650 (no spacing separation is needed for each cell). For those that wanted to use fewer cells, a dummy could be used.

Anyway, just some thoughts...


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## HarryN (Dec 1, 2005)

Hi Will - thanks for loaning me those parts.

Action - You have some very interesting ideas. I have a fairly long response post under development, but here is some quick info - maybe you can double check some items in it for me.

I read through JS various notes on his M6 - R thread, and he discussed using 6.8 V for the MN21 HOLA. His setup is pulse width modulated controlled vs the voltage controller I am planning to use is inductive. There are potenially substantial differences between the two at the bulb.

I need to do some more research on the topic, but I believe that in PWM control, the bulb is actually seeing a series of pulses at full V bat, which "average" to the targeted voltage. With the 9 x Ni cell setup, that is about 10.8 volts peak if my math is working today.

With a "conventional battery" direct drive setup, obviously there is no pulse, but the voltage sags. It seems like the M6 would normally see about 6.6 - 7.5 volts V bat with 3 x 123s, but definitely less than 3 x 18650s would provide. 2 might actually be closer, since they tend to be have a mid point voltage around 3.5 - 3.8 volts each IIRC. Under those conditions, further regulation might not be needed. Do you know anyone with experience running these bulbs with 2 or 3 X 18650 ?

Just so you know, DC - DC regulators tend to be available in computer voltages (3.3, 5, 12 V out) 6. x and 9ish are harder to find.

I will do some more reseach and add some more info. Please keep your ideas and data coming.


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## wquiles (Dec 1, 2005)

Action,

I never tough about it you mentioned, but I think that you might be right. If one looks at the 3x168S and 3x168A adapters from FiveMega, and since you can make those adapters in either series or parrallel, that could be the ideal setup for using 18650 cells. One would have to have enough space for the protection (if using bare cells) and the regulation circuitry, but width-wise it should not be any larger than a "D" size M*g, and no longer than a 1 and 1/2 "D" in length. Something to thing about 

Will


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## HarryN (Dec 1, 2005)

I am pretty sure that 3 x 18650s (and I am actually assuming the larger dia Pilas, not unprotected cells) would not fit inside of a D mag body. If it did, I think that would have already been done. If you find that this does work for you, that would be much cheaper than the solution I am proposing.

If you decide to regulate that for an incan use, it is a bit challenging because most existing volage regulators are not round, they are rectangular - which gives the side x side a configuration advantage.


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## wquiles (Dec 2, 2005)

HarryN,

You are correct sir. The 3x168A only fits on Fivemega's awesome "Fat Mag", not on the normal "D" bodies. My bad.

On a related note, I got the complete "C" series body, head, and tailcap, but for the "E" series I have only found the body and tailcap. Hopefully this is enough to get you started 

Will


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## HarryN (Dec 6, 2005)

Will - I received the parts - Thanks. I am not sure if the SF tailcap is the best solution for this application, but I will give it a shot. Certainly, there are other implementations that look interesting. I tried to send a PM but the server was busy.

I can see that I need to create a cross reference sheet to keep these projects and needs in order.

BTW - if you really are just after a round tube shaped 3 x setup, Lumatic built one from a 5 mega body designed for 3 x Pila 168S cells. He used R123s in a 3 wide x 2 deep config, partially under charged them, and made an adapter for the spacing difference. He is a little nervous about the 2 C draw, but it works. He posted some info about it on FF - not sure if it is on CPF or not.

I have tried bodies in that size range - it was a bit large for my hands, but fine for others.


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## wquiles (Dec 6, 2005)

Thanks for letting me know everything arrived safely 

Please keep us posted on your progress 

Will


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## HarryN (Dec 8, 2005)

I took some long looks at the existing dual bore tubes this past week, as well as the SF parts from Will. My initial impressions:

- Making a 2 x 2 AA body for the E series is not too hard, it will just take some time, money, patience, and a few protos to get there. I can make the total length a lot shorter if I put the "tail switch" on the front next to the head. It will not be the lightest body, with a first estimate of nearly 2 x the weight of a 2 x CR123 type light.

I cannot say I am particularly impressed by these switches, but obviously, they are popular. I am assuming the application for this is to run the E series incan bulbs and KL1 heads, but use AA size cells instead of the 2 x 123s.

Estimated price per unit for low volume runs - approx $ 150 - 200 / each. I will use the same 7000 series Al I use for my CR2 lights, which is nearly 4 x as strong, and 2 x as hard as the "conventional" aerospace 6000 grade Al.

The C series and M series look Ok as well for the 2 x 1 or 2 x 2 Pila ( as appropriate). Personally, I am not sure that a rear tail switch makes sense for that long of a light, but we can tell better after some drawings and renderings are made.

I should have enough data to make initial drawings over the Xmas holidays.


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