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  1. #1
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    Simpleton Xpg questions on first build

    After being a chronic lurker, have decided to jump in a diy led light. I haven't done the led thing before, just the old mr-11 types and have a couple of questions. I have a 1000ma buck driver I would like to use with 2 Xpgs. Was going to run them in series but I am unsure if my 7.4V 4400mAh Li-Ion battery will be up to the task.
    Also, I have orderer a b2flex driver and would use that on a 2 or 3 Xpg light after I complete(or screw up) the first one. Are there any advantages to going double or triple Xpg? It seems like the doubles are more popular. Also, what are the battery considerations of this?
    The led lights I have seen on this forum are just unbelievable! They put the old Union Pros I cut my teeth on to shame!

  2. #2
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    Welcome Dr Mushy

    7.4v Li ion will be ok for 2 xpgs with a buck driver but will start to dim towards the end of the charge once the voltage drops to about 6.5v (depending on driver). To maintain full brightness to the end you will need a 3 cell (11.1v) battery. This configuration will draw about 6-6.4 watts so a 4400 mAh 7.4v battery should give very roughly 4.5 hours runtime, give or take.

    B2flex is a great driver and will work well with 2, 3 or more xpgs. Triples give more theoretical light but the 20mm triple optics are considered less efficient than single optics of the same size. 2 x xpg with Ledil Regina reflectors are a popular choice for a helmet light, but there are lots of other options. Your 7.4v battery will be no use with three LEDs unless you use a boost driver. 14.8v would be better.

    Suggest you browse a few of the threads on this site as the subject has been discussed many times.

  3. #3
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    JezV-thanks for the reply!
    Judging from what I've read, I am a little afraid of the smaller 3 the up Xpg optics. I think I'll try 3 Xpgs with reginas straight across. I tend to agonize the details so I just ordered some Leds and reginas and am going to jump in!
    Another dumb question-glueing the regina to the star-artic alumina,JB Weld, or something else?
    Thanks-

  4. #4
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    I use Araldite epoxy but I imagine JB Weld would do. Don't need much and be very careful not to get it on the LED dome as you place the regina over it. You will need to trim the legs off the regina and align it dead centre over the LED; if it's not aligned you will get a wonky beam. I take a lot of care but align by eye. Haven't tried 3 x regina/xpg but 2 x gives a reasonably narrow beam with great punch. Good for a helmet light but personally I'd want more spread from a bar light. You are right about the small 3-up optics. My current bar light is a 20mm triple xpe and it's blown away by the twin xpg/regina combo. Its replacement will probably be XML but I haven't decided on number of leds or optics yet

  5. #5
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    Quote Originally Posted by Dr.Mushy
    JezV-thanks for the reply!
    Judging from what I've read, I am a little afraid of the smaller 3 the up Xpg optics. I think I'll try 3 Xpgs with reginas straight across. I tend to agonize the details so I just ordered some Leds and reginas and am going to jump in!
    Another dumb question-glueing the regina to the star-artic alumina,JB Weld, or something else?
    Thanks-
    Non-corrosive silicone works the best. I use a dab or two of hot glue to hold it in place, then silicone (non-corrosive normally takes a few hours to cure). Do not use JB weld since it is conductive; Arctic Alumina Adhesive will work...but is quite expensive to be using that much amount.
    Current Ride:
    Ibis Mojo SL-R - Medium - South Beach White
    '11 Specialized Roubaix Compact Rival

  6. #6
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    JB Weld is not conductive.

    It is, however, mildly capacitive, so don't use it to pot electronics with high impedance circuits.

    JB Weld, epoxy, double sided tape, or the aforementioned non-corrosive-silicone would work fine in your application.

    http://jbweld.net/faq.php#faq009
    From the link - "No. J-B Weld is not considered to be a conductor. It is an insulator."

    As an aside, in my testing, I have found that so long as the aluminum mating surfaces are very flat, and so long as the pieces are clamped tightly during the curing, that heat transfers well enough between the pieces of my achesalot-styled light. Granted, my measuring device is a very-highly calibrated fingertip, but both feel equally warm/hot at about the same time.

  7. #7
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    P220C- Thanks for the information! As my first LED light build progresses, it is one goofy looking build but we are learning. Thanks!

  8. #8
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    I'd go for odour free silicone for the reflectors as you never know when you may want to remove one. Plus I'm personally not terribly impressed with JBWeld - it's good enough for sticking things together that won't have any torsion or shear load on them though. In most cases, if I want something to conduct heat well AND stay stuck together, thermal paste and screws are more reliable in my limited experience.

    I'm not saying that JBWeld won't work for you, just some caveats to keep in mind, that's all

  9. #9
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    You can always use monkey spunk to remove any glue or silicone
    http://www.valetingproducts.com/2010...g-remover.html

  10. #10
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    I've always used a drop of arctic alumina epoxy....my wife must give me too much pocket money .

    As far as removing the optics, a firm twist breaks them free, as long as you can grip teh optic

  11. #11
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    Quote Originally Posted by Goldigger
    You can always use monkey spunk to remove any glue or silicone
    http://www.valetingproducts.com/2010...g-remover.html

    heh, that's funny, monkey spunk's what I call Stan's latex, though that's no much use for anything else

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