# Need help finding the perfect host for my Seoul P7 emitter...



## Gryloc (Feb 29, 2008)

Hello all. I recently purchased a Seoul P7 emitter from a sales thread. I thought that it would be a good opportunity to get my hands on some new technology. I actually did not like the Seoul P7 emitter at first because the LED package was so large, and the four dies were pretty spread out. However, when I saw actual pictures of the emitters from the seller, I noticed that the design changed a bit and the dies were closer together. Actually, I saw that the P7 resembled a Luxeon V a bit when it came to die spacing. I did a few tests with pictures of the Luxeon V emitter, and the Seoul P7 emitter, and I estimated very roughly that there was approximately a 0.17mm gap between each die of the Seoul P7, and approximately 0.12mm gap between each die of the Luxeon V. I always like the beam of the Luxeon V with different reflectors, and I still have a good respect for this monster from the past, despite the older technology. With this goofy looking Seoul P7, I hope to get a similar beam pattern when used with a large reflector, but I expect the brightness to be amazing!


So, I need help finding the ultimate host for this flashlight. I am on a budget, and I really cannot afford premium flashlights or one-off custom designs. I was hoping for something that looks nice (respectable), and not too cheap looking. I hope that it has a big, smooth or light orange peel reflector, or, it can easily handle a McR-38 reflector (which I own). I want to stay away from primary CR123 cells, but the use of 1 or 2 larger li-ion cells (16, 17, 18 millimeter by 50 to 67 millimeters long) would be great. I do not mind if it can handle C or D cells, since I can get cheap li-ion versions of them, or I can make a 6AA pack to fit in a 2D light.

Any previous flashlight that worked as a host for the 'ol Luxeon V should work for this flashlight. I do not mind modifying the reflector to let the ~9mm dome stick through the opening enough to focus properly. I found that the beam of a Lux V and my lonely McR-38 reflector looks nice. I do not mind removing material from this nice reflector. A C/D sized Mag reflector may work, but because the emitter has to stick up pretty far in to the reflector, I am unsure if the big Seoul P7 emitter will fit into the hole of the plastic reflector. Then the power leads have to be considered in to all of this. A host that uses a reflector with a shallow/short focal point will be ideal!

I am pretty open. Just remember that it will have to handle over 10W of heat. The LED has four dies in parallel, so it has a Vf similar to most single die LEDs out there, but it is rated to handle 2.8A of current. I may DD the emitter with one larger li-ion cell, depending on the Vf of the LED, to get over 2A of current. Some Li-ion cells may not be happy with that current, so I may have to buck the voltage of 2+ cells. I do have these circuits from DX that can be hooked in parallel on the output to increase current. I had two in parallel, running from 2 C sized Li-ion cells, that output 2A with no trouble. I may add another to see if I can get 3A.

So, I am naturally thinking of a 2D or 2C as a host (I do like the C-sized form), but I am not sure which other lights are out there that look nice that will meet my needs. I was searching though DX, but those lights look so bulky and awkward, and the reflectors seem cheap. I would like a light that is practical for light use, and something that nice enough so if I would choose to sell this one of a kind flashlight, I would get some interested buyers.

What do you have for me? I want something that can be used to parade around this Seoul P7, but I cannot afford the "Cadillac convertibles" that many others use. Thank you!

Here are some visual aids to get an idea of the emitter's size. The two pictures were taken by HgRyu, and the diagram was from the official datasheet...
(click for larger image)















-Tony


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## TigerhawkT3 (Feb 29, 2008)

First: good stuff.

As far as DD off Li-Ion, an ordinary (but good quality, like AW) 18650 should be able to handle 2-3A easily. With Li-Ions, you'll generally want to stay under 2C, so with a 2.2Ah cell, you're looking at 4.4A, and you don't need nearly that much. AW's 18650 protection circuits are short-protected at around 5A. For more on this, read about double-tapping in the Welcome Mat.

Maybe the McR-38 that works well with a LuxV will also work with a P7. I mean, in theory, it's basically just four P4s stuck together, so a Lux/P4-compatible reflector should work, and, given enough size, look pretty reasonable. LuxV reflectors would probably be a good, if uncommon, place to start.

The easiest host I can think of would be a Mag, cut down for a single Li-Ion (18650, C, or D). I can't see any reason why a DHS heatsink from H22A wouldn't work for this. (Sorry for the low coolness factor here, BTW.  )

I think that's all I've got for now. Good luck!


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## Drewfus2101 (Feb 29, 2008)

I would agree that the best host would be a D size Mag. Its pretty hard to find more size and versatility in a flashlight these days. Kai has some D size protected Li-Ions in stock now. He has them in singles and doubles. You could run a double (7.4V pack) in a 2D Mag with the P7 on any good heatsink and should be just fine. 

The fun part will be finding the right driver board. You might have to talk to the guys at TaskLED or Cutter (same guys?) and see if you can work something out. Otherwise I know some people have had success in running multiple drivers wired in parallel to up the output current. 

Regardless, this should be interesting.


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## yellow (Feb 29, 2008)

an idea for a smaller light, that still offers enough space to put electronics, single 18650, good sink but only a 27 mm reflector in (wich is the better one imho, because it is deeper and thus grabs more light)
http://www.dealextreme.com/details.dx/sku.9634
will get hot with a real full power running 4-die, but hey: its this small 
(reducing current a bit to get more runtime and less heat wont hurt at all)

If that "reduce current"-option is a NO, then imho one of these 2 18650 tri-quad Cree lights from DX/Kadomain are nicer than the Mag-Option. Smaller while offering good space for real sinks and for the 38 reflector


if that Led is 4-die parallel: isnt there that chance to get different Vf-ones, so that one runs on way too much power and thus dies quickly, then the 2nd one, the 3rd, ...
:thinking:
Sorry for that question, I'm not into this Seoul till now


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## evan9162 (Feb 29, 2008)

if it were me, I'd use a 3D Mag, some NiMH or NiCD cells, and replace the switch or wire up a low resistance MOSFET in place of the switch. With 3D cells, the voltage difference is just too small to justify a regulator of some kind.


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## Drewfus2101 (Feb 29, 2008)

evan9162 said:


> if it were me, I'd use a 3D Mag, some NiMH or NiCD cells, and replace the switch or wire up a low resistance MOSFET in place of the switch. With 3D cells, the voltage difference is just too small to justify a regulator of some kind.



Good point. 3 D size NiMHs fresh off the charger would be real close to 4V with a standing voltage of 3.6V. Thats pretty perfect. And they could handle the current draw no problem.


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## NetKidz (Feb 29, 2008)

I'm planning to put it into a Mag1D with 4x eneloop driving by 8x AMC7135. Maybe also with a D2DIM to do multi-level control. 

Eneloop should be able to stay above 1.1v under the load and 8x AMC7135 should be able to deliver about 2.5A.

I think the Aluminum MOP Mag reflector should be fine, but the opening must be enlarged a lot.


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## LukeA (Feb 29, 2008)

Drewfus2101 said:


> Good point. 3 D size NiMHs fresh off the charger would be real close to 4V with a standing voltage of 3.6V. Thats pretty perfect. And they could handle the current draw no problem.



I'd fill a 3D mag with 9 or 12 Eneloops in series running 2 1000mA buckpucks in parallel.


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## Gryloc (Mar 1, 2008)

Thanks for posting your ideas! I want something that is pretty efficient, so I am unsure about using 8 linear AMC drivers. I do like the idea of using large C or D NiMH cells, but I am not sure about one thing. Considering power density and voltage sag under load, which would allow for longer battery life: a C or D NiMH at 2.8A of current draw, or a C or D li-ion cell at ~1.4A of current draw? I would need three NiMH cells, and I always preferred a 2 cell C and D Mag form. The main downfall of using li-ion cells is that if I would sell the light, I would be giving someone 2 big, unprotected li-ion cells. This is so unless I use a D sized li-ion battery pack thats protected, as Drewfus mentioned. Kai also sells the charger for that pack. With 3 lower voltage cells, someone could use Alkaline batteries to some extent if they cannot find a charger for the big NiMH cells.

I need some more guidance in the battery topic due to the reasons of practicality. With 2 Li-ions, I can easily use a buck circuit to get the current that the emitter needed, no matter how the li-ion cell voltage drops. Here is the driver I can use. It is the one that I hooked two in parallel with success and got 2A on the output when using two li-ion cells as the power source:
http://www.dealextreme.com/details.dx/sku.3256

With the NiMH cells, as the voltage drops from use (not sure how long it will take), the emitter will dim quite a bit due to the reduced current (while still being bright). Maybe I should wait for the emitter before choosing which batteries to use. I will hook it up to my CC power supply and check the true Vf with my multimeter. If the Vf is really low (like 3.3V @ 2.8A), then there is no way to keep the current down if the NiMH cells do not experience any voltage sag. On the contrary, if the Vf is really high (4.2V @ 2.8A), then I doubt that the emitter will ever see the desired 2.8A for long, so the cool, one-of-a-kind emitter wont be shown off properly.

Also with the NiMH cells, if the Vf works out perfectly (very slightly overdriving the emitter with fresh cells -like 3.2A- and still powering the emitter above 2A after about an our), then I think that the D2DIM would be perfect (thanks -I forgot about that driver). I would get variable brightness, and everything would be simple and clean in the Mag. 

Evan9162, I understand the basics of electronics, but I would not know where to start on a basic mosfet driver circuit. It would be great to reduce the resistance in the switch, but the resistance, especially in the Mag C lights, should not be that high should it? The D2DIM would be very similar if I would wire the Mag switch to be momentary. I have modded a 2C mag to work with George's MaxFlex very nicely (I tweaked it so the button press was buttery smooth and easy to press, but not easy to bump accidentally). If the Vf of the P7 is really low, maybe a bunch of AMC drivers may work (if the driver does not consume too much of the voltage to power itself and contribute to voltage drop).

Yellow, did you just add that link? I was confused by your statement a few days ago because you described a nice sounding host, but you did not give a name or link. I was to busy to ask more. Thank you for that link. I just opened it after typing that above paragraph. That looks like a nice, solid, and simple host. I may order that to experiment with; to see the quality and see how it feels in the hand. I may use that light in the future for other mods, or if I haven't gotten the P7 into anything yet, it may go into that host. The reflector would have to go (maybe), but a McR-27 or McR-27L may be a good match up with the P7. If this host wont work, I will find a good use for it. We will see if someone can machine really quickly a heatsink for 4 Rebel 0100s and 4 McR-12R reflectors (I like the beams with those for their size). Maye someone can shorten the body part (bezel or head with just the reflector?) so those short reflectors will mate up with the Rebels. :naughty:

Oops, I got off track. I wonder how the LOP Mag reflector from Kai would work (if the hole is widened). Does anyone remember how hot the maglite got with an overdriven LuxV on a single emitter heatsink (like the o-sink, hotlips, and H22A's DHS)? Will heat be dissipated as well as a multi-emitter light (using the PTS or PQS heatsink)? I hope heat injected into the Mag battery tube will be transfered to the head well. Thanks all for the help. Great comments and suggestions! 

Tony.


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## yellow (Mar 2, 2008)

I think I added the link with editing the post a few mins after posting, but ... :thinking:

unfortunately the machining of this host is not perfect:
the treads are good, 
but no knurling on the body and the fins feel "sharp".
imho a perfect light for some 1st mods (cheap and enough room to put whatever in), but for sure not offering that smile a modded 6P or Inova puts into one's face


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## Drewfus2101 (Mar 3, 2008)

If you went with a 3D running direct drive it would pull as much as 2.8 amps. The best NiMH batteries you can buy have 12000 mAh capacity. So that works out to around (meaning not accounting for losses) *4.3 hours runtime*.

Running Lithium ion batteries it gets more complicated. If you went with 2 D size lithium ions, like the protected ones Kai sells, with a resting voltage of 7.4V and a capacity of 5000 mAh you would also have to use a few of those boards from DX that you linked to to buck the voltage down and (using 2 possibly 3 in parallel, which I've done with those same boards) get the current up. Thats where the math gets REAL tricky. 

If we assume those boards are around 80% efficient and do the power in equals power out we can crunch the numbers. 

Pin * 80% = Pout
Iin * Vin * 0.8 = Iout * Vout
Iin * 7.4V * 0.8 = 2.8A * 3.6V
Iin = 1.98A
5000 mAh / 1980 mA = *2.52 hours runtime

*So you would actually get better runtime on the NiMH batteries than the lithium ion batteries. 

*Disclaimer: this was done pretty quickly and could be done wrong. Feel free to correct my math.


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## Gryloc (Mar 4, 2008)

Your math is not wrong. However, the main reason that the NiMH batteries will win is because there will be three of them. Considering just two D sized cells of each type, the Li-ion would win due to their greater energy density (even the cheaper KD cell). However, considering a 80% efficiency of the converter, then the numbers start to get closer between the two. Of course, DD a LED from 2 NiMH cells would lead to very low current going to the emitter (if any) due to the Vf of the emitter.

So, I guess it comes down to using a 2 cell (with li-ion) or 3 cell (with NiMH) Maglite. Can anyone make any suggestions about driver circuitry that can buck 7-9V down to 3-4.5V at currents up to 3A, even when multiple ones are hooked in parrallel? The only one I can think of is the one I mentioned above (DX sku#3256). I am not sure about that driver's efficiency, but it could be found quickly by testing samples, I suppose. I have two drivers, so I will try to test them out later on. 

Should I wait to see the Vf of the Seoul P7 before making a decision on the exact driver and setup to use? Well, once it shows up in the mail, I will begin testing it. I will present some form of "Vf vs I" curve here.

Finally, does anyone have any beamshot comparisons of a LuxV behind a Maglite reflector versus some other well known light, or maybe in comparison with a Seoul P4 behind a Maglite reflector? Are KD's aluminum reflectors any better in beam quality, or in efficiency, compared to the plastic stock Mag reflector? What about those premium redesigned ones I heard about sold here on the CPF? Again, will a single emitter heatsink, like the hotlips and DHS transfer 10W of heat effectively? Thanks!

-Tony


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## Drewfus2101 (Mar 4, 2008)

The Lux and P4 should have pretty much the same beam shot. They have always been referred to as "direct replacements" for each other, and I have done numerous upgrades of Luxs to SSCs with no change in beam patterns. So that shouldn't be a worry. 

I would probably go with an aluminum reflector just because of the heat (along with glass lense). I've used Kai's stippled reflectors with P4s, and I didn't think that they imprvoed the quality of the beam any. I like the stock Mag reflector with P4s. I think you can get a aluminum reflector from Kai without the stippling. My heatsinks come from H22A and seem pretty beefy, but you might be better off to take one to a friend at a machine shop and let him copy it but make it deeper, as in sticks farther down into the Mag body (more aluminum = better heatsinking). 

You can use the same equations I used, but solving for the effeciency, to find the effeciency if you can measure the other factors if you have a driver board to test, power supply with voltage and current readout and 2 multimeters. I have that exact setup built but I'm out of those boards. I do have some on the way so if you havn't done that test by the time they get here I'll do it.


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## Gryloc (Mar 4, 2008)

Drewfus,

BTW, interesting name (play with words). Anyways, I was actually hoping for screen shots because the 'ol Luxeon V was an unique emitter. It had 4 dies placed close to each other in series-parallel, and it had a pretty broad beam that sometimes had a donut hole in the center with some reflectors due to the slightly darker area in the center where the 4 die corners meet. It was a unique, but very nice beam. I never seen a LuxV behind a smooth Maglite reflector, and that was why I asked. I wanted to see what I should expect with the quad die Seoul P7. The Seoul P4 is closer to the Luxeon I, Luxeon III, and Luxeon K2 emitters. Due to the single die placed in the focal point, the beam is very sharp and narrow with the Maglite reflector (and with other reflectors, in comparison). Even the Rebel behind the Maglite reflector has the same beam as the other Lux's, K2s, and P4s.

I wanted to see what the aluminum reflectors are like because I thought the LOP would remove some artifacts or maybe clean up the donut hole in the beam, or maybe the aluminum reflectors were slightly optimized to become more efficient. Maybe the aluminized coating may be of better quality, meaning more light reflected possibly. If there are no difference, then I wont bother. Don't forget that the LEDs do not emit heat out the front (like the incandescent does in IR light). If you feel some heat, that is actually because the pure light energy (which is steadily increasing due to the greater LED efficiencies) is being absorbed by your skin, which causes your skin to heat up some. A glass lens would be wise just because the light transmittance (I think that is the term) is much better than that of the polycarbonate lens. I worry that the cheap glass from DX/KD isn't that good (since I can see and detect a slight green tint), and how it compares to more expensive crystal watch lenses and AR coated glass.

So, anyone have beamshots, or know where to send me? That would be helpful. Thanks. It seems like too few still have the old beast in their torches. I always thought that they were a good part of LED history. I always admired them. I need to pick up a more premium binned emitter and just make another LuxV light for old times sake. I always got emitters from Future, so the Luxeon Lottery always provided me with V-binned LuxVs. :green:

-Tony


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## gswitter (Mar 4, 2008)

Gryloc said:


> Your math is not wrong. However, the main reason that the NiMH batteries will win is because there will be three of them. Considering just two D sized cells of each type, the Li-ion would win due to their greater energy density (even the cheaper KD cell). However, considering a 80% efficiency of the converter, then the numbers start to get closer between the two. Of course, DD a LED from 2 NiMH cells would lead to very low current going to the emitter (if any) due to the Vf of the emitter.
> 
> So, I guess it comes down to using a 2 cell (with li-ion) or 3 cell (with NiMH) Maglite. Can anyone make any suggestions about driver circuitry that can buck 7-9V down to 3-4.5V at currents up to 3A, even when multiple ones are hooked in parrallel? The only one I can think of is the one I mentioned above (DX sku#3256). I am not sure about that driver's efficiency, but it could be found quickly by testing samples, I suppose. I have two drivers, so I will try to test them out later on.


What about direct driving it with 2x or 3x Li-ion in parallel? Maybe cut down a Mag 2D and dual-bore for 2x 18650 or tri-bore for 3x 17670.


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## cmacclel (Mar 4, 2008)

As far as I know now one knows if any reflectors will work at all with the P7. I have 2 coming in and suggest before you buy anything waite for my input before wasting any of your money.

Mac


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## d1dd1 (Mar 4, 2008)

:thumbsup: great to have a professional tester :twothumbs

I will wait for your reviews 

Thanks


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## Nitroz (Mar 4, 2008)

cmacclel said:


> As far as I know now one knows if any reflectors will work at all with the P7. I have 2 coming in and suggest before you buy anything waite for my input before wasting any of your money.
> 
> Mac



Do you plan to test this in a Mag with stock reflector?

This is the light I would like to build for my father in law to use for work.


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## Rommul (Mar 4, 2008)

I think the possibility of an aspheric lens should be considered.


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## cmacclel (Mar 4, 2008)

Nitroz said:


> Do you plan to test this in a Mag with stock reflector?
> 
> This is the light I would like to build for my father in law to use for work.





Yes.

Mac


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## evan9162 (Mar 5, 2008)

> So, anyone have beamshots, or know where to send me?









Notice that the Seoul P4 doesn't focus as tightly as the other single-die LEDs (K2 and Rebel) - this is because its light source volume is much larger due to the "globby" nature of the phosphor deposition on the P4. Who knows if Seoul improved their phosphor deposition technique with the P7


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## Gryloc (Mar 5, 2008)

I am not sure about li-ion cells in series. Is there a problem with doing something like this? I worried that if one cell is damaged, it would always drain the others in parallel since the voltage tries to balance. I do not think that I would see any increase in capacity by doing this. All I would experience is an increase in complexity. Even if KD has slightly overrated capacity values for its 32600 cell, it is still very similar, or higher than using multiple cells in parallel. For example, 2*18650 cells would yield a capacity of 2 * 2200mAh = 4400mAh if using AW's nice cells, and 3*17670 cells would yield a capacity of 3 * 1600mAh = 4800mAh. Maybe this is slightly better than the actual capacity of the "5000mAh" D cells, but the price convinces me that the single li-ion D cell is more practicable. I just noticed that KD had 32650 protected cells (I only seen the 2D li-ion pack before). You know, this is all if I go with a single cell (cut down body). Now, if the Vf of the Seoul P7 is perfect for near DD with a li-ion cell's full range of voltage, and I am able to hook two li-ion cells in parrallel simply and safely, then I may stick with a 2C or 2D and make my own duel cell pack with the li-ion cells in parrallel. Hmmm, nearly 10Ah at ~3.7 for a 2D pack is nice without having to cut down or tri-bore the flashlight. I do have extra pack making supplies, from new battery wrap to protection circuitry. Can someone tell me that parrallel connected li-ions are safe, simple, and practicable? Thanks.

I really do not plan to start spending any more money on this thing until I get the emitter in my hands. Luckily, Mags are a cheaper host. I do have a spare untrimmed (cammed) and a spare trimmed Maglite reflector sitting in bubble wrap, so i can test the reflector without buying anything more yet.

So far, I know that many reflectors won't work with it at all. A parabolic reflector does not care what light source it is behind, so as long as I can get the tightly grouped dies as close as I can at or near the focal point, then the reflector will "work". However, I may have to modify the reflector by cutting it down near the opening. Even if it focused, and it "works", I will then have to worry what the beam will look like.

Thank you evan9162 for the picture. So, do you think that the beam will be like the combination between the Luxeon V and the Seoul P4? I mean this like there will be a broader beam, with a slight donut hole, but then the corona will be much brighter around the already broader beam. Maybe the glob of phosphor will help fill in the donut hole (but slightly darker hole should show up). So, I should expect a pretty soft beam, but due to the still comparatively narrow beam from the Maglite reflector, there should still be a good "punch" (throw-like characteristics) in the beam. Hmmm, it will be interesting. I was playing around in SolidWorks, and some reflectors will have to have the hole widened, and material removed from the bottom of the reflector to get it to sit close enough to the emitter (due to the big, soft dome) to focus. We will see. Oh, and I wonder if those 17 bond wires will great very ugly artifacts. I hope not. This is why the LOP aluminum reflectors may be perfect for this emitter.

Here is a quick screen capture of SolidWorks with the Seoul P7 behind a Maglite reflector. I hosted the picture quickly, so I didn't crop it yet. The emitter and reflector should be dimensioned correctly (close enough for now). 



(click for larger view)

Finally, I have my eye on H22A's DHS reflector. Since one version has an HAIII coating, I can isolate the slug better. I will have to remove the centering posts, and file/sand it perfectly flat, but because the heatsink and the Maglite is anodized pretty well, I expect good isolation between the can of the DHS heatsink and the Maglite body. H22A said that the HAIII is pretty resilient, and this isolation should exist, as long as I set the heatsink in carefully so I do not scratch either anodized coatings. I will have to center the emitter more carefully now, but it can be done. Maybe a centering jig can be made that sits over the emitter or something.

So far, I do like how this project is sounding. It seems like there is plenty of issues ahead of me to be solved to make this dang emitter work. Thanks again all for chiming in with ideas, suggestions, concerns, ooh, and pictures ! 

-Tony


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## kongfuchicken (Mar 5, 2008)

The standard mag reflector works perfectly well with the SSC P7.
I've just upgraded my old space needle 2 with one.
The led itself is massively large; it barely fits through the reflector's opening so I think this is going to be the main problem for integrating those.

The beam does give a very slight donut hole in the center but even a light orange peel reflector makes it indistinguishable at medium range. It looks a lot like the LuxV in the same setup to be honest.

I'm not actually running it at full power, more in the range of 5W or so with two SOB 750 boards; but it is a significant increase of output from the direct driven W4W luxeon V. I'd say about 50 to 60% brighter from the naked eye. The tint is also a bit warmer, yellow-ish instead of pink-ish.

I was way too tired last night so I'll be playing with tonight after dark.





I hope they'll make those available soon, they are definitively fun to mod with.


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## Gryloc (Mar 5, 2008)

Rats, you beat me to it (I live in Ohio). I hope it comes very soon. I will recheck my mail within an hour to see if it came late. It is encouraging to hear that it works with the Maglite reflector all right. Boy, that does look like a tight fit. Which heatsink did you use? I forgot, but what made the Space Needle different from other magmods? I was still lurking and a bit "fresh" around here when those were big. Could you take beamshots with both the smooth plastic Mag reflector as well as the LOP reflector? I am sure that you have a spare plastic one sitting around from the original mod, right? That would be awesome!

Boy, that does look like a tight fit. 

-Tony


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## kongfuchicken (Mar 5, 2008)

Sure, I'll see what I can find... it's not dark enough here yet.
The SN2 has a custom turned anodized heatsink with multiple fins, IIRC. I have no clue who made those, but it's probably the same machine shop Mr Bulk employs. The bottom is either press-fitted into the mag or it's welded in; either way, it ain't coming out.
The top part isn't anodized but it is firmly isolated from the rest of the body and there are no grooves that had to be sanded down like on the DHS which made my work much easier.


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## AlexGT (Mar 5, 2008)

How about putting this led with a FM 2.5 Throwmaster reflector? Since it is really deep it will probably focus the light better, How many lumens does that thing put out at full power?

Interesting thread!

AlexGT


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## kongfuchicken (Mar 5, 2008)

I have been eyeing one of these for a while, Alexgt.
Do you happen to know if they fit regular led heatsink pedestrals, like the hotlips or the DHS with no modifications?


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## AlexGT (Mar 6, 2008)

I tried one with a Cree on a custom made pedestal (from RCatR) and it would probably need to file away the threads at the base of the reflector in order to come to focus, maybe the P7 would focus better since it has a more radial pattern than the Cree.

Another thing to try might be an aspheric, I think if it is sligthly out of focus it would blend the light of the 4 dies to make one bigger spot.

AlexGT


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## kongfuchicken (Mar 6, 2008)

Alex, at full power it outputs anywhere from 700 to 900 emitter lumens. To power it at 10W, I'd need to find a converter that can handle currents as high as 2.8Amps and I don't have one at the moment. 

It sounds as if the fm 2.5" reflector does fit onto the pedestral as far as a regular mag reflector would go, but not enough to focus a cree. That's all it needs to do. If the opening is wide enough to let the pedestral in (about 15mm wide), the led will fit.

I don't have any aspheric lenses either so you'll have to wait until someone with a better equipped lab receives one.


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## AlexGT (Mar 6, 2008)

According to the specs it might be able to run DD with 1 Li-ion(D size) or with an extension tube to run 3 D nimh, I would go for the Li-ion for a more flat discharge curve. 

The diameter of the bulb aperture on the 2.5" throwmaster is 13mm, so some filing would nee to be done, I'm wondering what a 70 x 60 mm aspheric would do for that setup.

AlexGT


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## Gryloc (Mar 7, 2008)

:rock:
So, I got my Seoul P7 emitter Wednesday, but I was way too tired to do much with it, and also too tired to post my findings. Well, I was so busy Thursday, that I never had the chance. Argh. Sorry for the delay, Ace. Well, I used my CC power supply and tested this big beast, and I created a detailed Vf vs. Current chart. What I found was initially shocking, but I instantly realized why it was so shocking. I was amazed by the super crazy low Vf when the emitter is run at currents below 1A! This thing would make an ultimate replacement for the Luxeon V. I was worried about the datasheet voltages, and relying off of them for choosing whether I should DD or not. I am glad I took these measurements. Oh, so you know, the Seoul P7 is epoxied and held in place on a PIII heatsink, and all wires are soldered. So here is the data:









Now, remember that each die is seeing 1/4th the current (theoretically). So, that would explain the very low Vf measurements at lower currents (like below 1A). Should I create a table that shows the Vf of each die (pretty much the current divided by four)?

Well, with this data, I still could not better tell whether direct driving the Seoul P7 with a li-ion cell would work or not I know that the Vf at 2.8A is well below 3.7V, but I really do not know how well the li-ion cells will hold up. So, I did an old fashioned WTH test, where I hooked up some various li-ion cells up to the emitter in hopes that I do not destroy the Seoul P7 emitter. Here are a few of the larger, cylindrical, and un-protected li-ion cells that I own:
-8 X Toshiba 18650 cells "2200mAh" from a salvaged laptop battery (3 tested).
-2 X C-sized 25500 cells "5000mAh", most likely 3000mAh if that, from DX.
-2 X D-sized 32600 cells "5000mAh", capacity probably realistic, from KD.

With the advice of evan9162, I used two separate wires for the anode and cathode (in the "K" arrangement). One is to send my current, the other is to measure voltage. Both are soldered nearly directly to the power leads of the P7 emitter. Since a very slight resistance will drop voltage significantly in our scenario (Argh! Dies need to be in series!), I used very large wire for the current leads (18 AWG), and some thin IDE ribbon cable to measure the voltage. Not all of my li-ion cells are fully charged, so I showed the open circuit voltage (with no load) of each cell, fully rested for a day, then I showed the voltage across the emitter at 15 seconds (+/- 1s - I am not perfect) after the load was applied. I can post pictures of the setup if desired. Here are the results:





So, as theorized, DD is perfectly viable, but as you see, it is still not perfect. I do want the ideal 2.8A going to my emitter in my flashlight for at least several minutes. I could try to plot the voltage across the LED with the D-cell li-ion attached and do a run-time test to see how fast the voltage drops, but I do not have data-logging equipment. Therefore, everything would be done by hand at pretty long intervals (I do not want to sit and do a measurement every 1 minute (ulgh). 

For a quick and dirty flashlight mod, li-ion can work. NiMH, on the other had, I am clueless about. I only have a handful of good Eneloops (and a bag full of questionable Energizer 2500mAh HiMH cells). I do not own any C or D sized NiMH cells, so I cannot determine the effects on voltage due to sag under load. Can anyone else put their big NiMH cells on a 3A load to see the voltage across them? If I was working at my previous job (lovely co-op), I would have asked if I could use their expensive programmable load on some different batteries. That would be nice.

Finally, for your enjoyment, here are some pictures I took. I have a camera that takes lousy macro shots, so I could not get a decent emitter shot without it getting blurred. However, I was able to successfully take super macro shots using a little portable microscope. It was cheap, but it was the image quality was nice). It can be found at DX if you are curious (the 80X found here: http://www.dealextreme.com/details.dx/sku.1325). I modified it (I removed the ugly, and semi-useful graduated scale, and I trimmed of material from the top near the eyepiece so my camera lens could sit down as far as possible. I still got a round image that needed to be cropped somewhat, unless I used digital zoom (eww). All of them can be clicked on, and some will open up as a larger version. I tried to make it somewhat viewable by those still with dial-up by making only the main images full sized without clicking on them. Mods, if these are too big, please tell me and I will fix them.

Here is the emitter in the reel section, unopened. Then I tried to get a close-up shot by taking the picture though an eye loupe:


 




Here is a shot of the real P7 in front of a 3D drawing I made in SolidWorks of the P7 (click to make larger):





Now the good stuff! First is a closeup of the dies through the modified magnifier. I focused on the 8 pretty gold bond wires. Keep them in mind when thinking about pressing on the emitter... (click for larger version):





Here is two shots taken of the quad dies with the modified magnifier focused on the dies. I had troubles keeping it in perfect focus. I eventually figured out the best way to get it to stay.



Recognize those pretty EZ1000 dies? They look very nice. I am curious as to how the phosphor coating was applied. Notice the lacking of phosphor on the die edges? Also notice how the phosphor did not stick to the bond wires? Maybe this is due to the special phosphor mixture having a high surface tension when (and if) it is liquidous, causing the mixture to possibly pull on itself and thinning out on certain areas. I cannot really explain it? Anyone else want to give it a whack?


Here are some shots of the Luxeon V and the Seoul P4. The Luxeon V has a smooth deposition of phosphor on the four dies. Even the gaps between the dies are filled in. Note that the only loose Seoul P4 bare emitter I have is a damaged one. A reflector pressed against the dome side-ways, shearing one of the bond wires...



Just curious, but does the donut created from the Luxeon V get made worse by the fact that the gaps between the dies are filled in too thick? With the phosphor being too thick, it may make less light diffuse through, making the gap darker. With the latest conformal coating where the phosphor layer is super thin and even (like what is seen in the Seoul P7 and the Cree XR-E?), will the donut hole be as strong? I understand the fact that the main cause of the donut hole beam is caused from the lack of light being produced in the center near the focal point.


Finally, just for kicks, I took some shots of a TFFC K2 emitter, a Rebel 0100 emitter, and a R/O K2 emitter. These pictures can be removed if desired, mods. I just posted them for comparison use with my odd-fangled (is there such a word?) picture taking technique. (click for larger image)





Please note: sizes between each image is slightly different. Please do not make direct comparisons, pixel by pixel, of the dies. The image is distorted by the emitter's domes, and I also resized them slightly different. To compare them according to how our eye would see them, then you can scale them according to the black circle that surrounds each picture. This is the boundary in the magnifier where the image does not exist, and I think that they are the same size in each shot. Thanks.

So, enjoy the info and pictures. It may take a bit of time to devour all this junk that I am posting. Thanks for your patients!


-Tony



EDIT: 
Oh, a quick note: 

-The beam was very white, and if it were to lean towards any color at all, it would be on the blu-ish side. At low current levels, where you can look directly at the four small dies without destroying your eyes, all four dies look evenly lit, like the Vf matching is decent. I cannot tell at higher currents though. 

-The colors of the four dies were very similar, and I noticed that at super low currents, two dies have a hint of purple tint to them, and the other two dies have a hint of a more blue-ish tint. 

-I tested the results with an 50mm asheric lens, but I did not play around with the perfect focus to get a nice beam. I did focus it so I seen all four dies. They looked similar in every way, and they looked like 4 typical Cree XR-E ashperic beams that were close together. I did not get beam shots yet with the lens. 

-As for the reflector, I did not have the time or patience to perfectly trip away my Maglite reflector to get the optimal spot. I can't get beam shots until I permanently mount the P7 to an aluminum post (like on any DHS heatsink). 

-I can't think of anything more to comment on yet...


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## DaFABRICATA (Mar 7, 2008)

WOW! Nice write up and info.

I have 2 P7's coming to me tomarrow from friend in the industry. I plan to do a Surefire KT4 Turbohead. 

I hope these LEDs Rock!


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## lasercrazy (Mar 7, 2008)

I wonder if it would be easier to just use an incan voltage regulator instead of a led driver for now. Kind of like a modified DD setup.


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## AlexGT (Mar 7, 2008)

What is the material of the dome made of? Is it the gummy bear stuff, plastic, glass?

Thanks for the review! 

AlexGT


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## kongfuchicken (Mar 7, 2008)

The dome is definitively soft.
I don't know what it is but it's not glass. Whatever the P4 uses, this is the same stuff.

I found that the P7 outputs such little heat when driven at half power, yet almost twice more light than a luxV driven at 10W that I think I'll keep it there. Once they become more available and offer better bins, I'll think about making a host to accommodate full power. Like Gryloc said, it's basically what the luxV should have been from the start.


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## Nitroz (Mar 7, 2008)

kongfuchicken said:


> The dome is definitively soft.
> I don't know what it is but it's not glass. Whatever the P4 uses, this is the same stuff.
> 
> I found that the P7 outputs such little heat when driven at half power, yet almost twice more light than a luxV driven at 10W that I think I'll keep it there.




So is that about 350 lumens at half power?

Any pictures in action next to some know lights?


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## kongfuchicken (Mar 8, 2008)

Nitroz, I hate giving lumen figures. 
I am very ill equipped to make such claims.






Compared to a Surefire Z2 with a Malkoff M60 Q5, it looks twice as bright (spot about the same but more intense, spill much wider but about the same brightness).

Compared to a Surefire M6 running on mn20 and fresh cells, it looks slightly brighter (spot smaller but more intense, spill slightly brighter maybe due to color temp).

Take that for what it's worth; I can tell you it's not worth much... If I had to make a lumens guesstimate, I'd say 260 as it was comparable to the M6 on low output. Of course, I can't say for sure since the eye plays tricks on my eyes when comparing incan to led.










Note: I spent about 20minutes fighting with my camera settings and the camera settings kicked my arse so hard I was carrying my pelvis in a box. 
The color settings are completely out of whack and the focus was absolutely horrid. I couldn't for the life of me make it even focus at the proper range so I held it further away and zoomed from an editor. I haven't used this thing for a very long time and I apologize for the crude pictures.


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## Nitroz (Mar 8, 2008)

Thanks for the pictures KFC!

This is looking like it will be the perfect replacement light for my papas lost Lux V work light. I have always liked the output of the Lux V and this is even more exciting!


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## yellow (Mar 9, 2008)

still wondering if the Vf of each die can be made thus the same, that all of them get equal currents.

Till now I thought wired in series is at least more secure
(each die runs on the current measured)

:thinking:


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## Gryloc (Mar 10, 2008)

Its been a while since I last posted here. I feel like I have been moving too slow because there are many on the CPF that already has a P7 Mag built :sigh:.

I actually thought that this may be a rare emitter to work with, and few would want to bother with the odd quad die emitter. I was flat wrong. There is a thread in the marketplace where these are being sold for a good price, and people are going nuts over this thing. That is cool, but I thought that we (the first several owners of the P7 on the CPF) were going to be the few that will have this odd beast. I heard that SF is buying all these things out. Oh well...

Well, I am more confident with li-ion cells in parallel. This configuration is simple, safe, and I can easily deliver the needed current to the Seoul P7 without a bunch of parallel connected drivers to complicate things. I do not feel like waiting weeks to get the needed drivers, either.

However, I am still stuck on which light to use. 2C, or 2D (with li-ion)? I guess a 3C (with NiMH) is still an option if I can figure out the differences between them electrically (I need voltage sag or else I will deliver way too much current to the P7). I have put a couple of minutes on my Seoul P7 while running at 4A, and the thing does not get that hot. I wish I knew what was going on at the die level, however.

I managed to focus the Seoul P7 in a stock mag reflector. The beam is not that ugly (not too full of artifacts). In fact, the only problem I see is the donut hole, and when I defocus it to get rid of the donut, I get just a few streaks and dark spots, and the beam size increases a little. How much better can the beam get from using a LOP or a MOP reflector? I am hesitant on paying $25 for a LOP or MOP reflector at the Shoppe (KD is out of stock). I do not want to lose that "punch" that it has with the smooth reflector. The beam with the Seoul P7 fully focused (with donut), and slightly overdriven, is already brighter than 4 0200 TFFC K2s behind IMS SO20XA reflectors at 1200mA. I will try to get some pictures up later. I wish I lived somewhere darker to do meaningful beamshots. Dang the city lights!

Finally, I decided to buy a potential host for a Seoul P7 (for another P7 emitter down the road). How does this light look?
http://www.dealextreme.com/details.dx/sku.10367
It seems pretty compact, but features a nice, deep reflector. It runs off a single 18650 cell, so this would be a great host to feature an underdriven P7 for good brightness and decent runtime. The reflector seems very deep, and I hope the beam will look good. I will have to widen the emitter opening some for the P7 to focus, and I also have to find a way to pop open the aluminum Cree pill/heatsink thingy so I can modify the drivers and the emitter. Does this seem unrealistic? I hope there are some Conquerer M-C1 owners out there to comment on the quality and mod-ability. If no-one knows, then I guess I will have to wait for it to show up on my doorstep. 

So, please help me on my battery questions. This is the only thing holding me back from buying a host and the required HDS heatsink from H22A. I think that I will order the D2DIM from George. Thank you.

-Tony


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## Drewfus2101 (Mar 11, 2008)

The lithium ions in parallel is a good idea and there is no reason it won't work. Making it fit will be tough. The easiest way that I know of would be to get a D size mag and run some of the 17670 in a 3-to-1D holder. I would guess that the Mag body would need some boring, but thats pretty easy with just a brake hone cylinder from an auto parts store. I don't know who you would get those holders from though. If you could get 2 of those holders and mod them to run all 3 batteries in parallel and still have room in the Mag body to snake wires to actually wire the two holders up in parellel, that would be 6 of those batteries in parallel. At around 1800mAh each, thats 10800mAh and 3.7V. Not too shaby, but not easily done. 

You don't have to worry about what current your delivering to the emitter, just the voltage. The current will work itself out depending on the voltage. If you give it 3.5V, it will pull whatever current the data sheet says it does (in a perfect world I know, test this first) at that voltage. So as long as you keep the voltage where you want it or atleast less than 4.0V or 4.2V, then you should be fine. You can't give it 3.0V and 5amps. From your previous posts I think you know that, I just might be misunderstanding what your saying. 

I say don't worry about the reflector for now. Get the thing up and running then worry about that part later. I was not a big fan of the stippled reflectors and emitters. 

That host looks pretty good, as far as reflector goes, but the lack of battery will hurt you. Run time on 1 x 18650 will be pretty short, even underdriven. I guess you could get an hour out of it at 2 amps and still be brighter than most other lights. I hope it has enough heatsink in there for the P7 though. 

Wait...that reflector is designed for a Cree and the P7 is an SSC. I don't know how well they will work together, especially since this new P7 has 4 dies in it as opposed to 1.


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## ming560 (Mar 12, 2008)

How about using the rechargable Li-ion C or D battery?
e.g 
1) AW 3000A C-size Li-ion battery
2) DX's 25500 Rechargeable Lithium Battery (3.6V 5000mAh) 
http://www.dealextreme.com/details.dx/sku.5035
3) KD's Protected D Li-ion (32650/32600)
http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=4141
4) China battery: 32650/32600 Protected D size Li-ion for *[email protected] 
http://auction1.taobao.com/auction/item_detail-0db1-1e217f992e5eb77bb174dcad57854412.jhtml
5) China battery: 3.7V 5000mAh unprotected D size Li-ion for [email protected]
http://auction1.taobao.com/auction/item_detail-0db1-3f6ef52c9326937d52beb682ccd135e9.jhtml
6) China battery: 3.7V 5000mAh 32600 unprotected D size Li-ion for [email protected] 
http://auction1.taobao.com/auction/item_detail-0db1-c26380860ccadb7711e5f725d708b90c.jhtml

Will it burn out the P7 as using 2x18560 or C/D Li-ion in serial around 8.2V?


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## Gryloc (Mar 12, 2008)

Well, I did attempt to create a post earlier (yesterday) about using KD/DX li-ion cells, and some other thoughts, but my computer chose to restart randomly due to a recent spyware infection (which is gone now –yay). Naturally, I cussed out my PC and chose to post later. 

Well, I thought of using two of KD’s D-sized li-ion cells or two of DX’s C-sized li-ion cells in parallel was pretty practical. I cannot afford AW’s nice C-cells, and I do think that it would be too much work to bore out my Mag host to fit 3 17670 cells or some 18650 cells. I wonder if it would be worth the expense and time spent to have three quality cells in parallel versus a single cheaper D-sized li-ion cell. AW’s 17670 cells are rated at 1600mAh each (3 * 1600 = 4800mAh), and a single D-cell is rated at “5000mAh”, but is probably closer to 4200mAh (I think). Considering the cost of both of the cells and the work to hone the tube, I think that the D cell wins in my eyes. As for a 2C host, I could use AW’s C sized 3300mAh cells, but at $22 each, DX’s C-cells seems like a better deal. Those cells are labeled “5000mAh” like the D-cells, but I heard that they are closer to 2800-3000mAh.

When it comes to putting two C or D cells in parallel, I do have the supplies to make such a battery pack. I have fresh cell wrap for C and D cells, copper tape to connect the cells, kapton tape to insulate the copper strips, and I also have a couple of single-cell protection circuits to choose from. I have been eyeballing those protected D cells on KD. Those can be re-configured to work for this project. 

Ming560, thank you for those links you posted. Would you be able to help me navigate through those sites better? Have you ordered from the Taobao site before? I am hesitant when buying from an internet shop when I cannot understand the language (navigating through the checkout would scare me). I did navigate (sort of blindly) through that Taobao site and bumped into F-sized (32900) li-ion cells! I have F-sized NiCads and they are neat specimens. Two would be a bit shorter than 3 D cells. However, exept for added simplicity, I would not see an increased capacity (7000mAh * 2 vs. 5000mAh * 3). I did not dig through that site any further yet to see what other neat cells that are for sale.

I did do another run of tests on my Seoul P7 Monday night. I found that the Vf values changed slightly, but that could have been due to a poorer setup, or maybe the dies are naturally changing after long periods of time of use. With these latest tests, I measured the Vf from 50mA to 5000mA. The Seoul P7 is rated for 2.8A, but it seemed perfectly happy when ran at 4A (it did not get hot). I wanted to test as far as I could go, and 5280mA is the max that I could push with my constant current bench top power supply (rated for 18V 5A). That is not too scary, as only 1250mA per die and set of bond wires. Even at these currents, the emitter seemed happy. Of course, I am a power junkie who demands the most from my lights (but safely). As long as the emitter is cooled fine, then I think that the emitter will be okay. By the way, at 4A, the emitter is running at 14W, and at 5A, the emitter is running at 19W. I wonder if this will make some of you cringe out there.  Hmmm. I will try to post my findings later on. I have a lot of nice tables and graphs in Excel that I need to take screen shots of and host.

The reason I re-tested the Vf values was to confirm something. Since current readings on a multimeter is pretty inaccurate at high current levels from a battery (due to the resistance of the shunt resistor), I like to test current a different way. First, I measure the Vf of the LED when in the application. For my application, I put 2 slightly fresh charged D-sized li-ion cells (from KD) that I owned, in parallel, and I ran my Seoul P7 in DD with the cells using thick wire. I measured a Vf of 3.7V. Next, I would disconnect the LED from the circuit, and hook it up to my constant current power supply. I would vary the current until the voltage measurement (Vf) is the same as the forward voltage of the LED when in DD. So, with the Seoul P7, I disconnected the LED from the 2 cells, then hooked it up to my power supply. I soldered two small wires directly to the emitter’s leads to measure the voltage across the LED (as I did when it was connected to the 2 li-ion cells). I varied the current the best I could until I seen about 3.7V. Actually, I found that my power supply could not dish out the current enough to make put the emitter at 3.7V. That means that my power supply was maxed out at 5280mA, and at this current, I measured 3.68V across the Seoul P7. I estimate that when I run the Seoul P7 in DD with 2 parallel attached D-sized li-ion cells (not freshly charged), my Seoul P7 sees about 5300mA of current! By the way, at this current level, this emitter just amazes me!!! 

Since my Seoul P7 sees that much current, I may have to toss in a low, low valued resistor (probably a precision one) to reduce the current enough if the Maglite body does not have enough resistance already. Maybe a simple, but inefficient, linear current regulator will work (LM317 or higher powered one in current regulation mode). I wonder how long the LED will see over 5A of current with these massive li-ion cells. Can anyone help me figure out if the current will drop to a more desirable level? I am not extremely bothered by 5300mA, as I ran the Seoul P7 from 2 li-ions, with the LED at this current, for several minutes already, and the P7 does not seem to object (color shifts, intense heat). Actually, the Pentium 3 heatsink just slightly warms up when this ~20W LED is powered up.

I did find something interesting about the flux of the Seoul P7. It compares rather well, at the die level, to a 0200 TFFC K2 emitter. I made a small light box (cardboard box with white copier paper glued/taped to walls, and a light baffle in the center) to test the flux of the P7 as the current increased. I cannot give numbers in lumens, but I can compare the lux measurements that I got with the lux measurements taken of the K2. In a summary, the P7 performed identically to 4 0200 TFFC K2s in terms of flux. If you can estimate the flux of the K2 at certain currents, then compare that with the measurements with the light box, then you can roughly estimate the lumen output of the P7. Again, I will post more later.

Sorry about this long post. I just cannot help myself. I think that I said all I needed so far, including everything I typed yesterday before my computer restarted. Thanks for the patience! 


-Tony

EDIT: Ooops, forgot to add this. Ming560, using two li-ion cells in series (~7.4V) will fry the Seoul P7. If the cells do not sag at all (atleast to 4V), then the LED will see so much current, that either the bond wires will fuse open, or if those survive, the dies will get damaged from so much heat. This is why it is such a pain to design around 4 parallel connected dies. It requires so much current at a low voltage, and it is so hard to find drivers or to design around this feature. If only they were hooked in series, I would have been done with this thread after a few posts (I just needed to find a host). In series, it is easy to find a driver (Fatman, MaxFlex, Shark) to boost the voltage from 2 li-ion cells in series.


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## Drewfus2101 (Mar 12, 2008)

Gryloc said:


> That means that my power supply was maxed out at 5280mA, and at this current, I measured 3.68V across the Seoul P7. I



That just can't be right?! How is it that you can adjust the current up and down without changing the voltage? I've done the exact same tests, just with P4s and Q5s, and I can only adjust the voltage and emitter will _pull_ however much current it needs, but I can't adjust the current going to it, even though my power supply lets me adjust the current. Granted, I'm no electrical engineer (mechanical so this stuff is greek to me) so please explain if I'm missing something. But your numbers are way off from the graph too.


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## Gryloc (Mar 12, 2008)

Drewfus,

I used a laboratory power supply that automatically goes into CC (constant current) mode, or CV (constant voltage) mode. Depending on how I set the rough/fine voltage or current knobs, it will automatically change modes to meet the exact voltage OR current requirements that I set. In constant current mode, I think that it works like any constant current LED driver you can buy these days, where it automatically (but instantaneously) varies the voltage (uncaring of the specs of the LED) until the current is at the specified level. It will increase the voltage to the max that I set. 

For example, let’s say that I set the voltage knob so the voltage readout says 3.8V, but I set the current knob to its maximum, and then I hook up an LED emitter to the power supply. The power supply will go into CV mode instantly and send 3.8V to the LED, regardless of the current requirements. The LED will be powered to 3.8V, and depending on the LED, the current will probably go above 1.5A (let’s pretend this is an older K2 emitter with high Vf). Now, let’s adjust the voltage to 10V, then adjust the current knob to around 500mA (the general location where the last LED was powered at 500mA). Now, when we hook up the same LED, there will not be 10V being sent to the LED. Instead, since it automatically goes into CC mode, it will vary the voltage (ramp up/down?) until the LED sees the set 500mA. The voltage readout will now say something like 3.4V or so. Before I ever realized that a power supply could go into CC/CV mode, I did not believe that it was possible. Now, I cannot be happier that I have this power supply (it is almost more of a friend than my flashlights lol). Oh, and I am a student studying ME, so I understand where you are coming from. I am just really interested in electronics that are based around LEDs and related stuff. I am far from being an EE, trust me.

I also understand the concern about the differences in the Vf measurements made in the past few posts. I feel bad that I did not explain it enough. I noticed that after several minutes of operation, that the forward voltage of my Seoul P7 has decreased some. For those that will use current regulated drivers on this will not be affected. However, for those desiring to operate the P7 in DD, then I will have to be very careful. This Vf drop was first noticed by the almighty CPF member Newbie. His batch of K2 emitters showed noticeable forward voltage drop after several hours, and it continued continuously slower even after 60 hours. A lot of LEDs do this. However, I noticed my TFFC K2s having the opposite effect, where the Vf did not drop, but instead, it increased very slightly. 

I cannot fully explain it. It may be due to the fact that the dies are in parallel, and they may break in faster maybe due to the heat from the close grouping. I am not sure. I do have a quick graph to show my Vf drop. The first test was the results that you seen in my previous post (post #31). My second and third tests were back to back. The second was using a CPU fan to keep the heatsink close to room temperature, then the third was without the fan; using only convection cooling. By the end of that test, the heatsink was pretty hot. I was basing the current levels in my very last post from my second and third tests. We know that heat has an effect on Vf as well, so the Vf drop from the third test may be due to the heat the most. Here is a graph comparing Vf measurements from the three tests:





There was a 0.03V drop (at the 2800mA current level) after each test. Though this emitter was not run for hours on end, each test did take 20-30 minutes each (I must be just slow). Notice that I only ran the Seoul P7 to 4000mA on the first test because I was being extra careful. I relaxed for the second and third tests and let the current rip. Based from the first test, with and Vf above 3.6V, I had to interpolate/estimate the current level going to the LED. It was not very accurate. With actual measurements, I am more confident with my current figures. Do not forget that by the time that I get the current levels to 2.8A, things start to get warm, and that will throw off the Vf measurements some. I just fired up the Seoul P7 from off and set it to 2.8A, and it measures 3.44V cold. At 5280mA, I measured 3.7V cold. As soon as I apply the power, the Vf does drop due to the heat. 

I will post more details on these reports later on. I need to organize my thoughts more and then host all the pictures of the graphs...



-Tony


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## Drewfus2101 (Mar 12, 2008)

Wow great info. You might not be the first to post pictures of a P7 in a flashlight with beamshots, but your doing TONS to further this communities knowledge of that emitter. 

Keep up the good work!!!! Its people like you that keep this place running! Your right, this info will be critical to all the other people who are DD these things since there doesn't seem to be a simple driver for these.


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## ming560 (Mar 13, 2008)

Hi Gryloc,
I had ordered the battery from Taobao. For the

4) China battery: 32650/32600 Protected D size Li-ion for *[email protected] 
http://auction1.taobao.com/auction/i...57854412.jhtml
It is same as the KD's protect D size Li-ion, price is RMB$140 each around US$20 except shipping 

5) China battery: 3.7V 5000mAh unprotected D size Li-ion for [email protected]
http://auction1.taobao.com/auction/i...ccd135e9.jhtml
Mode No.: ICR3265
Normal Voltage 3.6V
Norminal Capacity 5000 mAh
Weight: 130g
rate discharge capacity: 98%(10A)
Operational Temperature -25~55 C
Dimensions: 32mm x 65mm ( will be 5mm more as adding the +ve cap)
Cycle Life: 1000(80%DOD)
price is RMB$50 each around US$8 except shipping . It is free of charge to help you add the +ve cap to the battery.

6) China battery: 3.7V 5000mAh 32600 unprotected D size Li-ion for [email protected] 
http://auction1.taobao.com/auction/i...d708b90c.jhtml
It is same as KD's 32600 3.7V 5000mAh D Li-ion Cell, price is RMB$95 each around USD$13.5 except shipping 
http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=3069


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## KDOG3 (Mar 14, 2008)

Wow. I would definetly like to see one of these in a U2...


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