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  1. #1
    jl
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    Flashlight Education

    I'm looking to build a couple of "high-powered" flash lights with my kids this summer. I'm on the figure out what I don't know research.

    I would like to build a light that uses an 18650 cell, and a 3-up indus star LED.

    The problem is I don't know anything about flashlight drivers. Here's a list of some I have found, do any of you know if these are any good, would they work with what I am trying to do, or am I approaching this the wrong way. From what I've read I would need an ~2.8a driver.

    I'm also unclear on how you would wire one of these driver to the LED. Is there a serial vs. parallel preference?

    Skool me...

    Thanks, in advance....

    LED Driver List.

    8X7135 / 2.8 amp ( selectable mode ) XML driver

    3-Mode 2800mA LED Driver Circuit Board for Flashlight (DC 2.7~4.2V / 2PCS) - Free Shipping - DealExtreme

    Constant Current LED Driver Board - 4 Mode, 3-4.2v, 2.8A

    3-Mode Regulated Circuit Board for XML, MC-E, SST-50 and SSC P7 (2.8A Max.)

    b3Flex Product Description
    Ride On!

  2. #2
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    Ok- where to start here...

    first off - that Indus star has 3 XP-G emitters in series. You won't be able to run them off a single 18650 without using a boost driver. none of the drivers you mentioned are boost. 3 emitters in series sum the voltage forward (vf) that the emitter array would require. At full power for a XP-G (1.5A) - that vf would be about 9.9volts. A single 3.7v lithium cell can't supply that voltage either using a linear or buck style of driver.

    If you had a triple board that was wired with each emitter in parallel, now you'd be able to use a single cell, as each emitter would now have a ~3.3vf, and in parallel the driver sees each separately. The problem here is that now the current demand to run each emitter at full power is summed. (1.5Amp*3emitters=4.5A required). None of these drivers can output that much, so you'll be running the emitters at much less than full power. Take one of the 2.8A drivers, and that would mean each emitter is being driven at ~930ma. Still pretty good output from a XP-G at that power range though. ~275lumen each maybe for ~825lm theoretical output? Ballpark at least.

    A flashlight run at full power like that, off that one 18650 is going to have a run time of less than one hour.

    Personally - you'd get more output using a single XM-L emitter. You'd get a little less light, but better runtime using a single XP-G2.

    Or for $23 go to your local Home Depot and find one of these Defiant brand XM-L tactical flashlights - SKU# 639226.

    The light is a freaking beast for cheap. You can't even buy the XM-L emitter on a 20mm star that comes in it for less than about $11, and here you get a whole light, with batteries, ready to run.

  3. #3
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    That indus star is individually addressable if you remove those bridges, so it will be usable wit AMC7135 based driver if wired in parallel.

  4. #4
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    I'm not clear on the extent to which you want to 'build'... are you saying "assemble from existing parts" or "start with a hunk of metal and create a flashlight"?

    It would also help if you settled on what characteristics you want. I'm assuming bright, since you've spec'd a triple. Do you care about runtime? Is overheating a problem for you? Color temperature? Color rendering? A broad flood beam, or a beam that throws a long distance? Single 18650 or multiple?

    The 3-up star is bright, driven properly, but you can get very good results with a single emitter. A single emitter will simplify things for at least this build. (Having soldered a triple star in parallel, I can say that I needed steadier hands or more soldering skill.)

    You might consider looking at the P60 dropin... you'd learn about drivers, reflectors, emitters, and you could choose from a wide range of available hosts. (SolarForce is my budget host pick... they're only slightly more expensive and dramatically better quality than the typical ***fire crap.)

    You didn't ask, but I'll mention anyway: get good protected batteries from a good vendor. Panasonic or Sanyo spring to mind. There are lots of rip-off clones out there of ***fire cells, so you never know what you're getting.

    Of the vendors on your list, DX has a reputation for slow shipping. George at task is great, as is Shiningbeam. I have no experience with the others. Fasttech.com is a recently new player to the field, and I've been very happy with them.

    As far as more places to waste time, er, I mean research, check out budgetlightforum.com and candlepowerforums.com. Both have their place, though I'll let you draw your own conclusions about their respective personalities.

    Good luck!
    The study du jour: can one's reputation be artificially inflated by simply putting a request for rep in one's sig?

  5. #5
    jl
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    borrower,

    Thanks for the reply. As for a build, I'm thinking about starting with a some copper tubing, drill, and solder, etc. I'm not looking to retrofit, I want something unique for them to work on.

    I want to build a compact light with a single 18650. I want to have a multiple level switch and driver so I can get a longer run time, but I don't care about a short run time on high. Boys like lumens :-). A couple of hours would be fine.

    My boys want to have "high-power" lights that's why I was thinking about the 3-up. I do NOT have a lot of soldering experience. If you have a _bright_ single emitter that you would recommend, I would be more than happy to investigate it.

    This is sort of a run-up to building my own set of bike lights. Which P60 drop-in would you recommend if I were to go that route? I would probably get rid of the reflector use a carlco lens.

    Thanks for asking more questions and any more input would be great. I've heard good things about shiningbeam. I've ordered from ledsupply with great results, but they don't have any 'flashlight battery' led-drivers. So I'm on my education mission.
    Last edited by jl; 03-07-2013 at 12:07 PM.
    Ride On!

  6. #6
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    Quote Originally Posted by jl View Post
    borrower,

    I want to build a compact light with a single 18650. I want to have a multiple level switch and driver so I can get a longer run time, but I don't care about a short run time on high. Boys like lumens :-). A couple of hours would be fine.

    My boys want to have "high-power" lights that's why I was thinking about the 3-up. I do NOT have a lot of soldering experience. If you have a _bright_ single emitter that you would recommend, I would be more than happy to investigate it.

    This is sort of a run-up to building my own set of bike lights. Which P60 drop-in would you recommend if I were to go that route? I would probably get rid of the reflector use a carlco lens.

    Thanks for asking more questions and any more input would be great. I've heard good things about shiningbeam. I've ordered from ledsupply with great results, but they don't have any 'flashlight battery' led-drivers. So I'm on my education mission.
    I want to jump back in, just trying to help, - If you want to run any emitter, whether the Indus triple, or a single XM-L, or whatever, a single 18650 cell isn't going to run at close to the maximum output of any of these drivers for more than about 45-50 mins on high using the best 18650's out there. cheaper ones will have shorter runtimes.

    To run the Indus at all off a single battery, you'd have to rewire it in Parallel, now that I see the bridges are removable, it wouldn't be hard to do with minimum work - but as a skilled solder-er, and I've built a couple of lights with triple XP-G setups, it is some tight work to get the wiring in there, and clear the paths a triple optic will need to mount to those optics properly. Easily done if you have patience though.

    rewiring the Indus in parallel means that you would then have to split the current output from your drivers to each of those emitters. say you use the 2.8A 7135 driver you listed above. This means again, each emitter would be running at ~800-900milliamp of current. For an XP-G that's going to be about 300lumen per emitter output - so neighborhood of 900 total. A single XM-L emitter driven by the same driver will have a bit more output, and simplify your wiring. It would also allow the use of reflectors, which are generally considered a little more preferable for flashlight use.

    Heat will also be an issue - using copper pipe, aluminum, or whatever. Flashlights sit still with no airflow over them. Bike lights can fudge the dissipation a bit since we are typically in motion. As "boys like lumens" was stated - why use low when there's high? :-) I never had much restraint in those days either.

    IlluminationSupply.com is a good place to look for drivers/supplies too - US-based and quick shipping.

  7. #7
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    Quote Originally Posted by adrenalnjunky View Post
    I want to jump back in, just trying to help, - If you want to run any emitter, whether the Indus triple, or a single XM-L, or whatever, a single 18650 cell isn't going to run at close to the maximum output of any of these drivers for more than about 45-50 mins on high using the best 18650's out there. cheaper ones will have shorter runtimes.

    To run the Indus at all off a single battery, you'd have to rewire it in Parallel, now that I see the bridges are removable, it wouldn't be hard to do with minimum work - but as a skilled solder-er, and I've built a couple of lights with triple XP-G setups, it is some tight work to get the wiring in there, and clear the paths a triple optic will need to mount to those optics properly. Easily done if you have patience though.

    rewiring the Indus in parallel means that you would then have to split the current output from your drivers to each of those emitters. say you use the 2.8A 7135 driver you listed above. This means again, each emitter would be running at ~800-900milliamp of current. For an XP-G that's going to be about 300lumen per emitter output - so neighborhood of 900 total. A single XM-L emitter driven by the same driver will have a bit more output, and simplify your wiring. It would also allow the use of reflectors, which are generally considered a little more preferable for flashlight use.

    Heat will also be an issue - using copper pipe, aluminum, or whatever. Flashlights sit still with no airflow over them. Bike lights can fudge the dissipation a bit since we are typically in motion. As "boys like lumens" was stated - why use low when there's high? :-) I never had much restraint in those days either.

    IlluminationSupply.com is a good place to look for drivers/supplies too - US-based and quick shipping.
    I almost entirely agree with adrenalnjunky. My only disagreement is this: when I was a very novice solder-er with a junk soldering iron, there is no way I could have made a triple work. Now, as a slightly less novice with a semi decent soldering iron, it was hard.

    As noted, a single xm-l emitter will match or outperform a parallel triple. I'm not really up on which optics mate well with the xm-l, but I'm sure the info is out there.

    If you aren't going to go with a manufactured host, I wouldn't worry too much about the p60 dropin. It's just that it happens to be a very convenient package for the reflector/led/driver.

    For a little inspiration, a "sled light" here: Simple light and something completely different: Homemade Triple P60 | BudgetLightForum.com
    The study du jour: can one's reputation be artificially inflated by simply putting a request for rep in one's sig?

  8. #8
    jl
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    borrower and a-junky,

    Thanks for all of your input. That homemade triple p60 thread is the kind of idea I'm looking for, with the single configuration. So you've more or less convinced me of not subjecting myself to the pains of doing the triple wiring. So now I have to ask, if you were going to select for yourselves the best bang for the buck (meaning runtime vs. lumens) using a single cell 18650 what setup would you use (e.g., driver and LED)?

    Now my adult brain is kicking in and I'm thinking a really good overall light might also be a great project.
    Ride On!

  9. #9
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    Lots of different ways to skin a cat, and I should note that I haven't done this build, so ymmv. I've linked to fasttech because I've ordered from them a number of times and always been satisfied with their prices/quality/delivery speed. In one case where they sent a slightly wrong thing, they made it right without giving me any stick.
    Optic: $0.86 20mm 15-Degree Optical Lens/Optic for Cree XM-L LED Emitters - 20*12.8mm at FastTech - Worldwide Free Shipping
    Emitter: $6.90 Cree XM-L T5-5C1 / 4000K Neutral White LED Emitter with 16mm Base - T5-5C1 / 4000K at FastTech - Worldwide Free Shipping (I happen to like neutral white tint)
    Driver -- 2 choices.
    Wow factor but major heat dissipation issues: $3.05 8* AMC7135 2-Group 2~5 Modes LED Flashlight Driver (Nanjg 105c) - 3.0V ~ 4.5V / 2800mA constant current / 17mm at FastTech - Worldwide Free Shipping (nice too because it's soft-switched between [L-M-H] and [L-M-H-blink-blink])
    Half the brightness but nowhere near the problems with heat: $2.89 4* AMC7135 2-Group 3/5 Modes LED Flashlight Driver (Nanjg 101-AK-A1) - 3.0V ~ 4.5V / 1400mA constant current / 17mm at FastTech - Worldwide Free Shipping (not soft switched)

    Other misc. carp to think about... thermal paste between the star and pill, a pill of some description to mount the star onto, decent wire (teflon jacket is nice), rosin core solder (preferably leaded), a switch of some description, perhaps some springs for battery contact. I'm sure I've missed something, but this might get you started.
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