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Thread: My extreme micro flashlight dream project

  1. #1

    Default My extreme micro flashlight dream project

    Here is my project/dream:

    I already have permanently in my pocket:
    - the most extreme mini cellular phone: HTC Tytn II (powered by a Li-Ion 1350mAh battery)
    - the most extreme mini laser pointer: 125mW green (in metal tube and powered by 2xAAA batteries)
    Now I would like to add to my pocket the most extreme flashlight.

    My goal is to obtain the most extreme total output in the smallest size.
    When I say extreme I mean that a LED(s) lifetime of at least 1-2 hours, a continuous and total runtime (for battery and heat) of at least 5 minutes and a temperature that doesn't hurt my hand are my only requirements. For the rest it must be the most extreme possible configuration available at any cost.

    For the smallest size (it must be *always* in my pocket) I thought to share the battery of my cellular phone or of my laser so I thought to one of the following three options:
    A) I power it with the Li-Ion 1350mAh battery of my cellular phone, attaching the LED(s) externally to the back plastic flat battery cover of my celluar phone
    B) I power it with the 2xAAA batteries of my laser pointer, attaching the LED(s) to the metal cover of the batteries of my laser point
    C) I cut the head of my laser with a saw, take new battery/ies with an higher voltage (choice: Li-Ion AA(s), RCR123s, 16500, 17500, 17670, 18500 or 18650 cell), and do the same as point B building a new case to host the different battery/ies, that are better to get the most out of the best LED(s) such the Rebel (100..), the Cree XR-E (Q5..) and the SSC Z (P4..)

    I would start with the first problem: A, B or C? what do you think about them?

    Mailint

  2. #2
    Flashaholic* LEDcandle's Avatar
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    Default Re: My extreme micro flashlight dream project

    I'd say you should figure out why your 2 x AAA used lithiums can't seem to power up the LEDs you bought before jumping onto any 'extreme' project

    If you had no cost restrictions, you might want to consider buying a bright small light like Modamag's Draco or Drake or Lummi's Wee instead of trying out DIY at this point. (not saying its not good to learn, but taking it in steps is always a good thing.. )

    Those lights I recommended are barely bigger than the batteries used to power them (10180 and 10280), which are 18-28 mm only, and can put out up to 100+ lumens for more than just 5 minutes. At that size, the output will definitely be a show-stopper.

    Just some comments on your suggestions :-
    A) Your single Li-on battery puts out about 3.7v... so it won't power your LED to the "extreme". Maybe 600-700ma if direct driven. Heat WILL become an issue at that current drive if the LED is just stuck onto the back of your phone (plastic).

    b) You already figured out your 2 x AAA doesn't power up the LED brightly... so why thinking of using this method again? Anyway, it doesn't seem practical to just stick an LED on your laser pointer.

    c) Don't cut anything. Just buy a cheap light from Dealextreme since cost is no restriction to use as a host. Then buy whatever LED you want and either direct drive it or use the most powerful converter you can find.

    I think you should continue learning more about some modding basics first. We are all here to help you. No doubt in short time you will be up and running with a practical and workable mod
    Last edited by LEDcandle; 10-09-2007 at 08:14 PM.

  3. #3
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    Default Re: My extreme micro flashlight dream project

    Is a Surefire Titan out of the question? At least it will match your "Tytn" haha...

  4. #4

    Default Re: My extreme micro flashlight dream project

    Quote Originally Posted by LEDcandle View Post
    I'd say you should figure out why your 2 x AAA used lithiums can't seem to power up the LEDs you bought before jumping onto any 'extreme' project

    If you had no cost restrictions, you might want to consider buying a bright small light like Modamag's Draco or Drake or Lummi's Wee instead of trying out DIY at this point. (not saying its not good to learn, but taking it in steps is always a good thing.. )
    Hmmm.. I investigated about these three flashlights and I think I will buy, in addition to a Fenix L2D Rebel 100 2xAA, a Draco, that I will try to dismount to see how I can those circuitry and cases for my purpose.

    Thanks for the suggestion!

    Quote Originally Posted by LEDcandle View Post
    Those lights I recommended are barely bigger than the batteries used to power them (10180 and 10280), which are 18-28 mm only, and can put out up to 100+ lumens for more than just 5 minutes. At that size, the output will definitely be a show-stopper.
    Just to add an information, of the three you mentioned I saw that only the Draco put out more than 100+ lumens.

    Quote Originally Posted by LEDcandle View Post
    Just some comments on your suggestions :-
    A) Your single Li-on battery puts out about 3.7v... so it won't power your LED to the "extreme". Maybe 600-700ma if direct driven. Heat WILL become an issue at that current drive if the LED is just stuck onto the back of your phone (plastic).
    I just tried to direct drive a Cree XRE on round 2cm diameter aluminium(?) PCB on the air with the cellular Li-Ion battery and the current was around 650mA. After about 10 seconds it became how.
    I also tried with 2 of them in parallel and the current was around a total 1000mA.
    Isn't there a good heat sink solution to reach some minutes of runtime?

    Quote Originally Posted by LEDcandle View Post
    b) You already figured out your 2 x AAA doesn't power up the LED brightly... so why thinking of using this method again? Anyway, it doesn't seem practical to just stick an LED on your laser pointer.
    I still think to the 2xAAA alternative because I got around 50mA with direct drive. With the step up converter it can be all another story.
    For example the Fenix L2D Rebel 100 2xAA is rated 180 lumen. I bought one of it to try it with 2xAAA and see what happens.

    Quote Originally Posted by LEDcandle View Post
    c) Don't cut anything. Just buy a cheap light from Dealextreme since cost is no restriction to use as a host. Then buy whatever LED you want and either direct drive it or use the most powerful converter you can find.
    Why are you suggesting this now? aren't you anymore convinced about the Draco greatness?
    AND... what about the laser? I think it's a waste of size and weight to carry three separate batteries for LED, laser and cell. phone.
    Unless I'll be totally happy with the Draco as third independent object to carry, I think that sharing a battery is preferable.

    Quote Originally Posted by LEDcandle View Post
    I think you should continue learning more about some modding basics first. We are all here to help you. No doubt in short time you will be up and running with a practical and workable mod
    By the way, I saw that the FluPic driver is no more "buyable" because the modder producer is out of activity since january. May I ask you what's the best currently "buyable" alternative? and how can Modamag sell the Draco if the FliPics are no more available?

    Thanks in advance for the clarifications

  5. #5
    Flashaholic* Echo63's Avatar
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    Default Re: My extreme micro flashlight dream project

    just get a Orb/Lummi Wee
    check the lummi subforum here on cpf
    flashlight collector by day
    flashlight user by night

  6. #6

    Default Re: My extreme micro flashlight dream project

    Quote Originally Posted by Echo63 View Post
    just get a Orb/Lummi Wee
    check the lummi subforum here on cpf
    Isn't the Modamag's Draco better? I think it has a significantly better size/brightness ratio. Don't you agree?

  7. #7
    Flashaholic* Gryloc's Avatar
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    Default Re: My extreme micro flashlight dream project

    Mailint,

    Sorry I didn't respond sooner since my last post in that other thread. It has been one of those crazy weeks were I was working a bit later, and as a result, I was dead tired. Well, I have been giving this a lot of thinking. For an extreme light, I keep thinking back to using li-ion. Lithium ion cells are just great due to their high power capacity, convenient voltage, and variety of sizes.

    I came up with a couple of battery and circuit combinations (with stuff easily and cheaply available) that could be used to power 3 or 4 of the new tiny rebels with those new 11mm diameter reflectors by McGizmo at a high enough current to be stunning. Sure this is a custom light, but it will be so unique and so bad-ass! The entire diameter of the flashlight shouldn't too much bigger than 22mm for three Rebels and 25mm for four Rebels.

    I considered how you just want extreme light in small size, also considering that you do not care about battery life (run time) or total life time of the LED (let's push it). Well, unfortunately, I could not promise 5 minutes of runtime, but instead, 30 minutes to 90 minutes (depending on battery used and LED configuration). The only thing that may be limiting this light from offering more than 10 minutes of on time is heat. Holding this light in your hand is most recommended, but if you let it heat up too much, then I guess the LED life would decrease a few 1000 hours (far from hitting your 2 hour goal).

    Expect at least twice the output than your Rebel 0100 Fenix. These lights will be taxing your li-ion cell, but within limits so it should be safe. As long as the batteries can provide the power, then the driver circuits will send enough current to the LED.

    So, what are these ideas? In all these examples, I speak of using 18650 cells due to their good capacity, and decently small size. Any li-ion cell used must be a protected one (with integrated protection circuitry). The current of these cells will be within 1C and 2C of the 18650 li-ion cell. 1C means running a cell at a current equal to it's capacity in amps (a 2400mAh cell at 2.4A is 1C). I hear that you should not run a cell at over 2C (~4.8A for the 2400mAh cell) due to the possibilities of thermal runaway. Some protection circuitry cuts the power at so many amps, so then the protection circuitry will be the limiting factor. Where shall I start?

    Single emitter lights:

    1. This idea was proven in that concept I spoke of a while back in that other thread. It features a singe Rebel 0100 or Cree XR-E Q5 bin (Q2 bin may work better), but the emitter will be running at around 1.5A amps to 2.0 amps. The emitters will be direct driven from the Li-ion cell, but Georges80's D2Dim circuitry allows you to vary the brightness from very low to max power. The circuitry does not regulate current, but uses a PWM to dim the light. It will save you power when you need to find that keyhole or read a book, but can then be set to "stun" mode. It is a pretty tough circuit, too! Low Vf is needed here, so the Rebel may be the best choice. The Q5 could be great if you can find one with a low enough of a Vf (Q4s and Q5s are known to have oddly high Vf). A Q2 supposed to have pretty low Vf, and they are still very bright. With a decent 17mm or 19mm reflector, you will get a decent balance of throw and spill. The beam should be like that of your Fenix, but the intensity will be amazing.

    You will be blown away by the brightness! Using evan9162's measurements (http://www.candlepowerforums.com/vb/...d.php?t=169547), I have calculated that the Rebel 0100 will produce ~335 lumens, and according to evan's measurements of the Q4 (http://www.candlepowerforums.com/vb/...d.php?t=172379), the XR-E will produce somewhere around 341 lumens. After losses, expect about 300 lumens. Does that sound about right? Again, as long as the Vf is low, and the flashlight does not have too thin of aluminum walls, then the thing should not get very hot in your hand (I have found).

    Multiple LED lights:

    2. The design I think that will be the most promising is this one. It uses a single Shark boost circuit to provide either 3 or 4 Rebel 0100s with 980mA of current. You can turn down the current with the trimpot if desired. You can turn down the current and still get amazing brightness. Firstly, if you deliver 980mA to three series connected Rebel 0100s, you will get 702 lumens (minus any losses). With four Rebel 0100s, expect up to 936 lumens! Heat is a limiting issue, but so is the power the li-ion cell can dish out.

    With the efficiency of the Shark driver considered, the Shark will draw from 3.62A to 4.01A from the li-ion cell when using 4 Rebel emitters and the Shark will draw from 2.66A to 2.95A from the li-ion cell when using 3 Rebel emitters. The 18650 li-ion cell should be able to handle those loads. Beam shape, according to McGizmo, should be similar to Surefire SL4 (or a Luxeon V mated with an IMS20 reflector). I will discuss McGizmo and the beamshots later.

    So, there is a hell of a mini monster. Even if you turn down the current to 500mA going to each LED, 3 Rebels will produce 435 lumens while the driver draws 1.24A to 1.38A from the battery and the 4 Rebels will produce 580 lumens while the driver will draw 1.66A to 1.84A.

    3. Finally, you can use two smaller li-ion cells (RCR123 sized) in series to power 4 Rebels using the newer SOB buck circuit. You will need two of these SOB circuits to power 2 series connected Rebel emitters. There is no real advantage of using this design. You get similar brightness as the Shark design for 4 Rebel 0100s, but you just draw half of the current from the batteries. This design is if you prefer using the smaller cells. Unfortunately, you have to pay for the two SOBs and squeeze 2 of those tiny circuits in the flashlight now.

    ------------------------------------------------------------------

    Okay, what do you think? I had more ideas, but they were using a different boost circuit than the Shark driver (George80's Fatman). It had a limiting factor (you can only draw less than 2A on the input side), so this meant using two in the same light. They were also slightly larger in diameter than the Shark (the Shark is a bit thicker though). I had multiple other designs because of the Fatman's input current limits.

    As for McGizmo, check out this link: http://www.candlepowerforums.com/vb/...d.php?t=174089
    In that link, McGizmo showed some prototypes using his McR-10R reflectors. One light uses 3 Rebels and reflectors, the other uses 7. Both are just beautiful looking and the really performed well! This thread solidified my confidence in the multi- Rebel and McR-10R reflector combination. I probably would not have thrown out those ideas if it weren’t for him!

    BTW, I am not sure what percentage of light is lost due to the reflector and lens efficiencies, so I did not account for any losses in with those lumen figures given. Also, brightness will vary a bit by several percent depending on the binning of the LED (flux, forward voltage, and tint). There are numbers out there (percentages) for the losses to expect, but I do not know them. I will be getting a lux meter soon, so I can finally take some somewhat accurate measurements of my flashlights. This will help make comparisons between flashlights, atleast.

    Oh, and I gave the input currents to give you an idea how long that li-ion cell will last. You can take the mAh ratings from the cell and determine the runtimes. I give a range of current draws because as the voltage of the li-ion cell drops, the current draw will increase to make up for the power needed by the LEDs and driver circuits. The first current draw is based on a cell voltage (under load) of 4.1V, while the last is based on a cell voltage of 3.7V.

    I see that you learned about V*I=P and how Pin=Pout and how the buck or boost driver would function with different cells. I hope you understand that your AAA would not be able to handle the load if you want a light with far more brightness than the Fenix. AAAs is great mostly for tiny lights. Hopefully you do not mind using an 18650, 18500, or 17670 li-ion cells. They will make the flashlight have a diameter of 20mm to 22mm, but they are still pretty compact, and the cells pack quite a punch (in power). The light can be a bit past 100mm long, but that length will vary depending on the cells used. All you have to find is a decent host that the stuff will fit in. You never know, you may be able to find someone here that can turn out a flashlight body for you with a lathe. Local machine shops may be willing to make something for you, too.

    So, there are my ideas. If I had the funds and the time right now, I would make a light like this for myself. Besides, I have a slew of other projects in front of me, from a pair of LED headlights (a revision of a previous pair I made), to a tiny Rebel 0100 based Maglite Solitare that uses a 10440 li-ion cell (AAA sized). If interested, I can discuss this stuff in more detail during this weekend. I may mess around in SolidWorks (3D cad program) and draw up a light that uses three or four Rebels, or a single Rebel or XR-E.

    What are this Modamag Draco and the Surefire Titan lights? I am a bit out of the loop with these nicer premium flashlights. I saw the Orb Wee, though. Will these lights be any brighter than the Fenix lights like you wanted? Just wondering…

    Finally, I was thinking about your green laser. I believe that there are constant current drivers that can feed the right current and voltage to the laser using a higher battery voltage (li-ion cells), right? This way you may be able to add the laser to the flashlight, or maybe just share the battery. If not, you could probably just have the two separate in your pockets. Do you like holsters for things like flashlights? Since you like to EDC stuff, maybe that will be a good idea. The EDC forums would have you covered in this area. Later...

    -Tony

  8. #8

    Default Re: My extreme micro flashlight dream project

    Tony, thank you LOTS for your long message! very useful explanations! I read every word of it.

    Considering all what you wrote, about the currents you mention I fear that it would come out too big for the big needed battery and for the big needed heat sink / case.
    When I tried to turn on a Cree XRE LED on an aluminium thing big like a little coin (2cm diameter x 1mm) at 650mA of current I felt it very hot after about 10-15 seconds of runtime.
    I think that for driving this LED at 1.5 amps or 2.0 amps you need a big heat sink to keep it on for at least some minutes without damaging it and your hand the first time you try it.
    I think that this interesting "CREE 3x XR-E Q5 Plug & Light Kit" from Led-tech is indicative of how big the heat sink must be just for running (continuously) them at a typical 700mA:


    This thing seems little but is 45mm x 45mm x 25~45mm.
    Ok, holding it in your hand can help, but how much?

    Furthermore, when I tried to direct drive a Cree XRE with a 1650mAh Li-Ion battery I got only ~650 mA. I think that for reaching 1.5 amps or 2.0 amps I'ld need a much bigger battery, while keeping the whole thing little is very important for me.

    As a last note I already carry two other devices with battery: the mobile phone and the laser pointer. Why not gaining size and weight by sharing at least the battery with one of them? I think that it would bring a big advantage.

    ____

    After extensive research on CPF I found that the micro flashlight with the highest total output/size factor is the Modamag's Draco and that is so higher than the alternatives that I don't think I could do better.

    The 18650 battery is about 4 times bigger than the battery that this flashlight use.
    Size chart:
    10280 battery - 10mm x 28mm (Draco use this!)
    10440 battery - 10mm x 44mm (AAA size)
    14500 battery - 14mm x 50mm (AA size)
    16340 battery - 16mm x 34mm (nominal CR123a size)
    17500 battery - 17mm x 50mm
    17670 battery - 17mm x 67mm
    18500 battery - 18mm x 50mm
    18650 battery - 18mm x 65mm
    The external size of the Draco is 43mm x 13mm (47mm x 13mm with lanyard), for a weight of only 7 grams.
    For comparison, a Fenix L2D Rebel 100 is 147mm x 21mm, for a weight of 56 grams.
    For what I read I think that the total output of the two is not very different.
    This is why this Draco is upsetting my old plans...

    I created a preview of my last mental production:



    The 125mW laser uses about 650mA out of the 2xAAA lithium batteries.
    An UltraFire 10440 Li-Ion cell has a capacity of 500 mAh. 2C is then 1000 mA.
    It seems theoretically good for both the Draco and the laser (alternatively)

    What do you think about it? wouldn't it be cool?

  9. #9
    Flashaholic* Gryloc's Avatar
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    Default Re: My extreme micro flashlight dream project

    mailint,

    Well, I am a bit shocked that you are going to an even smaller and dimmer flashlight as the Draco. Isn't the Draco put out less light than a Fenix P2D CE or Rebel? Sure it is super tiny, and decently bright for it's size, but will you be impressed with more floody beam and less light? Sorry, but it just seems like a step backwards from your own Fenix. I bet that you can still fix up your Fenix to have it produce more light (replace the driver with a higher power one and upgrade the emitter).

    Well, I drew up those tri- and quad- lights in Solid works, and it is neat to see how small they are, even thought they use a larger li-ion cell. Even with the 17670 cell (or two RCR123s), it is shorter than the Fenix P3D (takes 2X CR123 cells), which is 114mm long. With a 17500 cell, the light would be shorter than the Fenix P2D (1C CR123 cell), which is 80mm long. The reason for it's small size is the small Rebels, which are not very tall, and the short, tiny McR-10R reflectors, which are only 6.88mm deep (versus the >15mm deep reflectors used in the Fenix). Overall, this is a pretty compact light that packs a punch. It is a little fatter than the Fenix in the head, but that is only by a few millimeters from the reflector cluster.

    Here is that drawing (click on it):

    Shown in this picture is a AA battery (14mm X 50mm), the tri version using a 17500 cell, the quad version using the same cell, and the Fenix P3D (21mm X 114mm), a popular light. The tri version has a head that is 24mm in diameter, and the quad version has head that is 27mm in diameter. Both lights have a body that is 19mm in diameter, and they are both only 75mm long. With a 17670 cell, they will be about 90mm long. It is neat to draw them up on paper to scale using a ruler. They seem big, but when you consider the output, they are actually tiny beasts!

    If heat is a concern, then you do not have to power them each at 1A. even with each at 350mA, you will have a light that is over 300 lumens for the tri- and 400 lumens for the quad-. The lights will stay cool since they are running at 3W and 4W. A dimmer can be added, or multiple modes, that can give you bursts of 500mA, 700mA, or 1000mA if you want to show off.

    With your XR-E, what was the bin? It sounds like your XR-E has a higher Vf (forward voltage), or your li-ion cell is not fully charged. My 18650 cells were salvaged from an 2-3yr old laptop battery, and they were sitting at below 1.0V for many months (almost ruined). With a slow and crude charge, I got it back up to 4.15V each. When I had it in that flashlight that ran the Rebel at 1A, I made sure the cell was at about 4.0V so I do not send to much current to the Rebel. The cheap flashlight also had a bunch of resistance in it, further dropping current to a safer level. If I would hook the 18650 cell straight up to the Rebel 0100 with wires, the current would exceed 2.3A and I would rip the wires off. Also, Rebels have a slightly lower Vf than most emitters. So, check to make sure that your cell was fully charged, and the XR-E does not have too high of a Vf (Q4 and Q5 bins naturally have a higher Vf). How did you measure current? Just checking.

    So, I am not telling you to not go to the Draco, I am just telling you to re-think things some. You can't base the power of li-ion by attaching a single XR-E to it, and you cannot assume that your flashlight will cook your skin due to that tiny star board. Flashlights have a bit more mass. I agree that maybe three or four Rebels at 1A for more than a minute may cause a little trouble, but decreasing power will help with the heat, and you will still have insane brightness.

    If you really like such a cute little light like the Draco, then why not mod a small light for more brightness (and maybe a slightly reduced runtime)? A Fenix L0D takes a 10440 or AAA cell, and you can add the latest Rebel 0100 and that nicer reflector to it. DD the Rebel with the li-ion cell, or use a higher current driver (I seen one on Kaidomain that is 10mm in diameter and powers an emitter at up to 800mA from a NiMH AAA cell). I just worry that you will not be fully satisfied with a super small light that produces less light than a Fenix CE or Rebel model. I also do not see how you will power the laser from the same battery as the flashlight as of now until something is modded a bit. Wow it is getting way too late (or early) for me since I have to work in the morning. Yikes!

    -Tony

  10. #10

    Default Re: My extreme micro flashlight dream project

    Quote Originally Posted by Gryloc View Post
    mailint,
    If I would hook the 18650 cell straight up to the Rebel 0100 with wires, the current would exceed 2.3A and I would rip the wires off
    Hi!
    Can I ask you how did you calculate the 2.3A?
    The official data sheet of the Rebel (http://www.lumileds.com/pdfs/DS56.pdf) doesn't show the current for over 3.5Vf and I was unable to find a plot of the voltage drop/current of a 18650 Li-Ion battery...

    The tri-quad light you described seems interesting to me, if possible.
    The main reason why I'm pointing to the tiny Draco is that I want an EDC light that I can *always* carry in my pants along with my mobile phone *without nuisance* and without appearing ridiculous, even in casual show offs.
    Those rare moments when I need it or when it's ideal for a show off to a friend it must be there, wherever I am, for some seconds (<5 minutes) of spectacle.
    I fear that a light as big as a Fenix P1D is already too big. Some already observe that my HTC Universal mobile phone is too big for EDC. They would probably laugh at me if I would fill the other pocket of my pants with a visible flashlight.

  11. #11
    Flashaholic* Gryloc's Avatar
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    Default Re: My extreme micro flashlight dream project

    mailint,

    Lumileds' document sheets can be rather vague sometimes since it is so hard to create datasheets for every bin for forward voltage. Those numbers are given so one would have some basic numbers to design their product around. It is like this for any LED emitter.

    As for the Rebel, did you see the data from evan9162? Here again:
    (http://www.candlepowerforums.com/vb/...d.php?t=169547)

    He is not the only one. Jtr1962 did a test of them and you can see the results here:
    http://www.candlepowerforums.com/vb/...t=89607&page=5
    He showed numbers up to 1500mA, but the numbers are still useful.

    You also missed the great generation were the all-knowing, truth-seeking master thrived on the CPF, and his name was Newbie (a.k.a. Jarhead from even longer ago -before I became a member). He still does research and things on his own, but just not as much on the CPF. Here is is evaluation of the Rebel 0100:
    http://www.molalla.net/~leeper/rebel.htm
    He has a bunch of pictures that may take a bit to load, but it is worth it. He dives deep into the technology. Really, he does! He blasted the top layers of the Rebel off just to see the electrical contacts below the die. He will be missed.

    So, real numbers will always vary from the ones of a datasheet (maybe not so much for lumen figures though). I have not done a voltage vs. current graph of my Rebel, but I sure got over 2A when I had very little resistance in the wiring and flashlight. When I receive some new Rebels in the mail (hopefully this week), I will take some measurements, graph them, and share them on CPF. For my case, I feel bad not having data to prove it, but it is possible.

    As for voltage vs. current draw of an 18650 cell, I do not know much about it. I guess you can experiment. For starters, if anything, here are some examples:
    http://www.candlepowerforums.com/vb/...d.php?t=117117
    From my understanding, I think that you can follow the line for the specific current draw and see the voltage sag over the runtime of the cell (which is shown in amp-hours). I would like to know more about voltage sag of li-ion cells, too. At my workplace, we use a large, programmable load with voltage monitoring and graphing software. I wonder if my boss would let me buy some time to test different batteries on the equipment. That would be sweet.

    I guess that I can see your point of going really small. Since it will not be used often enough like a tool, why have a flashlight that may create a bulge ? Besides, to a non-flashaholic or person that is aware of some of the latest technologies, the Draco would be pretty damn impressive. Many may try to pull out their mini-maglite to beat you . That is a common thing that us CPF members face. There are pockets that work for 1AA and single CR123 lights, like cargo pants (rather large), side pockets on carpenter pants, or just the change pocket (often plenty deep and easy to pull lights out of). Those tri- and quad- Rebel lights are neat and really ultra-small for their power, but since they are a little fatter, they would work better in a small pocket on your side (change pocket or leg pockets on carpenter jeans) or a holster. Thinking about that light, I may have to attempt it myself and put it on my to do list...

    -Tony

  12. #12

    Default Re: My extreme micro flashlight dream project

    Thanks for all the informations!

    Quote Originally Posted by Gryloc View Post
    As for voltage vs. current draw of an 18650 cell, I do not know much about it. I guess you can experiment. For starters, if anything, here are some examples:
    http://www.candlepowerforums.com/vb/...d.php?t=117117
    From my understanding, I think that you can follow the line for the specific current draw and see the voltage sag over the runtime of the cell (which is shown in amp-hours). I would like to know more about voltage sag of li-ion cells, too.-Tony
    In the meantime I tried again to direct drive my old 3 wire Cree XR-E P3 LED with my cell. phone battery that is a Li-Ion 1350mAh.

    These are my measurements:
    V immediately before I connected the LED: 3.940
    V immediately after I connected the LED: 3.580
    V after 10 seconds of runtime: 3.500
    A (current) during the runtime: 900-950mA

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