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  1. #1
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    My new handcrafted 4xXPG

    Just a teaser for now. More to come.








    Need to finish the cover mounts, some drilling for wires, make remote switch with led, wire the batery pack ....

  2. #2
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    The carbon fiber is cool.
    Are you going to run the leds in series or 2 strings of two (2S2P)?
    What maximum current are you thinking about running?
    Can't wait to see the finished pictures.
    Thanks for sharing the build so far.

  3. #3
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    I'll be running leds in series at 1300 mA since that's all i can squeeze out of Maxflex. Batterypack is 3S1P and 3S2P LiIon at 11.1 V nominal, which is pretty much optimal for this configuration.

  4. #4
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    That should squeeze almost every lumen out of the XPGs. I usually don't run them past 1000 mA. Heat becomes an issue and with that a loss of lumens.
    Troutie did some test of the XP series at maximum current vs lower currents and light output.
    I can't remember which of his many and threads it was in.
    The finding were that at a certain current there was little to no perceptible increase in light. Just increased heat and decreased battery run time.
    Maybe someone remembers where that post is at.

  5. #5
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    I only use max mode on high speed rides or in rain, so the heat has never been an issue. I made a double XPG R5 earlier with the same max current setup, and never had heat issues on high mode even riding uphill at about 10km/h. The housing barely got warm. But if I could set maxflex to 1500 mA, now that would be nice, squeezing every lumen out of the emiter. Battery run time won't be a problem, since I'll be using 3S1P 3000mAh LiIon 18650 on shorter rides, which should provide me with approx. 2+ hours of runtime on max and 3S2P setup for longer rides.

    2x XPG R5:


  6. #6
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    Quote Originally Posted by Toaster79
    I only use max mode on high speed rides or in rain, so the heat has never been an issue. I made a double XPG R5 earlier with the same max current setup, and never had heat issues on high mode even riding uphill at about 10km/h. The housing barely got warm.
    vs.


    There is a huge difference in thermal designs of your two housings. The 2X has a good amount of surface area exposed to open air. Standing still natural convection will work well, and while moving you'll have tons of forced convention through the heat sink.

    Your 4X has enclosed slots, which will severely inhibit airflow both while standing still and riding. Also the construction (aluminum clad with carbon fiber composite) will likely inhibit hear transfer to the outside air trapping heat in the housing. Not to mention, you've doubled the amount of heat you're trying to dissipate.

    I suggest you ditch the CF skin and let the aluminum transfer the heat. Also mount a nice big heatsink to the top like your 2X has.

  7. #7
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    I was gonna mention something like that, but I've had people doubt my heat dissipation designs so I didn't have a whole lot of room to talk, hahaha.

    The CF will insulate the housing trapping heat. The fins in the middle are sort of a dead air pocket that will probably be minimally effective unless you turn it sideways. The CF lip will cause the air to pass right over instead of guide air into the sink.

  8. #8
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    Just a thought how well does CF conduct Heat .

    Formula one cars have carbon discs and they have a hell of a lot of heat to get rid of

  9. #9
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    Quote Originally Posted by troutie-mtb
    Just a thought how well does CF conduct Heat .

    Formula one cars have carbon discs and they have a hell of a lot of heat to get rid of
    Yet another new thing I learned.






    You've got this going on right now:

    The air passing over the back of the SUV just keeps going back...if the car were rounded, it would hug the curvature and air would flow downward a bit before going further back.

    Maybe you could round the edges and get some aerodynamic properties to help the air "hug the curve" and guide itself into the fins.
    Last edited by chelboed; 06-17-2010 at 12:02 PM.

  10. #10
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    Quote Originally Posted by troutie-mtb
    Just a thought how well does CF conduct Heat .

    Formula one cars have carbon discs and they have a hell of a lot of heat to get rid of
    I think forumla one uses carbon in their brake systems due to its ability to withstand extreme temperatures, not it's ability to conduct or disipate heat.

    There is likely a poor thermal path between the aluminum and CF shell, unless toaster used thermal paste/epoxy over the whole part. Regardless whether he did or not I still feel it would disipate more heat if air flows directly on the alumium and if the heat sink fins were't buried.

    I'm not a thermal systems engineer, so take my advise with grain of salt. Worst case you try it out and it heats up too much. I'm definitly curious to see if it would or not.

  11. #11
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    I have used this link to see how bad or good materials may be for conducting heat, it has a good chart and makes it clear that Aluminum is really the best choice, considering cost and weight, most other things that are likely to be used are not so good.

    http://www.engineeringtoolbox.com/th...ity-d_429.html

    At 25 degrees C:
    Carbon = 1.7
    Epoxy = 0.35
    Aluminum = 250

  12. #12
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    So all of you engineers are wondering if the body will withstand the extreme conditions? No, it won'T! I'm aware of that, since I've mentioned how I'll be using it. Making your theories if it's gonna consume the heat or not based on the charts ... Been through that. If it's gonna heat up, I'm gonna lower the max current, and if that's not gonna do the trick, I'll just rip it apart and redesign it.

    But 'till than... I'll let you know if it works in theory AND in praxis ... or not

    we'll see

    edit: but I appreciate your concerns
    Last edited by Toaster79; 06-17-2010 at 04:44 PM.

  13. #13
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    Quote Originally Posted by HuffyPuffy
    I have used this link to see how bad or good materials may be for conducting heat, it has a good chart and makes it clear that Aluminum is really the best choice, considering cost and weight, most other things that are likely to be used are not so good.

    http://www.engineeringtoolbox.com/th...ity-d_429.html

    At 25 degrees C:
    Carbon = 1.7
    Epoxy = 0.35
    Aluminum = 250
    Carbon as C? Diamond is also carbon (as far as it is the most heat conductive material on this planet) and so is graphite (as used for lubrication, wonder why)
    What epoxy? Arctic Alumina is epoxy (although its glue)

  14. #14
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    Quote Originally Posted by Toaster79
    What epoxy? Arctic Alumina is epoxy (although its glue)
    The carbon material you're using is woven carbon fibers held together with an epoxy binder.

  15. #15
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    F1 cars, use CARBON in it's most basic form not Carbon Fibre, the Space Shuttle uses the same on it's nose cone to with stand the heat of reentry therefore it does not conduct heat.

    Which is the main advantange of a Carbon frame, mid winter you can rest your nads on the top tube without your heat being conducted out and your balls freezing off.

    A Carbon Fibre Strip stuck on is much cheaper though

  16. #16
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    Quote Originally Posted by Turveyd
    F1 cars, use CARBON in it's most basic form not Carbon Fibre, the Space Shuttle uses the same on it's nose cone to with stand the heat of reentry therefore it does not conduct heat.

    Which is the main advantange of a Carbon frame, mid winter you can rest your nads on the top tube without your heat being conducted out and your balls freezing off.

    A Carbon Fibre Strip stuck on is much cheaper though
    Either your frame is too big or my nads are too small...cause I got plenty of room there

  17. #17
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    Which is the main advantange of a Carbon frame, mid winter you can rest your nads on the top tube without your heat being conducted out and your balls freezing off.
    i like to use a toptube pad in the winter for this reason.

  18. #18
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    Carbon-fiber heatsink (far superior to aluminum and copper):
    http://www.thermocomposite.com/

    From what I gather, it matters a lot just how you arrange the fibers. Heat transfer is very good along the length of the fibers, but not nearly so good in other directions.

    So, will the OP's CF housing be any good? I want to know. Hook up a thermometer to that thing and try it with and without the CF.

  19. #19
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    Dang that carbon sync looks dangerous!!

    Hate to crash with that type sticking toward me...
    "mountain biking and flyfishing, what more do you want?" - Yeah, I said it

  20. #20
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    Remote switch:


    Maybe I'll make another one with led inside

  21. #21
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    how do you soldier those...I have some tiny switches w/led internal and they are a bear for my inexperienced ability.

    Very clean job there!
    "mountain biking and flyfishing, what more do you want?" - Yeah, I said it

  22. #22
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    how are you holding it together Carlco 10417 and XPG

    How are you keeping the Carlco 10417 and the XPG held together?

    Do you use Artic Silver epoxy to glue the XPG PCB to the heat sink and then use silicone to glue the lense in place holding it to the PCB?

    jmitchell13
    You have your light open at either end do you have to wash out any dirt or mud after a ride?

  23. #23
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    Quote Originally Posted by cam999
    jmitchell13
    You have your light open at either end do you have to wash out any dirt or mud after a ride?
    All of the lights posted in this thread are Toaster's. I was just quoting a previous post of his.

  24. #24
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    Quote Originally Posted by cam999
    How are you keeping the Carlco 10417 and the XPG held together?

    Do you use Artic Silver epoxy to glue the XPG PCB to the heat sink and then use silicone to glue the lense in place holding it to the PCB?

    jmitchell13
    You have your light open at either end do you have to wash out any dirt or mud after a ride?
    Yes, I use Arctic Silver epoxy to glue the stars to the heatsink, then I leave a gap of about 0,05mm between the acrylic lens cover and heatsink for the silicone and apply some pressure so the lens cover gets almost flat with the heatsink and the lenses, so there's no space between any of them.

    Although the sides are open there has been no issues of dirt coming inside. But if it happens, a splash of water should solve it. Been using the light in some heavy rain and had no problems.

  25. #25
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    Quote Originally Posted by jbflyfshr
    how do you soldier those...I have some tiny switches w/led internal and they are a bear for my inexperienced ability.

    Very clean job there!
    That's how It's done:


    Soldering iron, tin, salvaged board from an old car stereo with momentary switches, two pieces of heatshrink, wire



    Prepare two pieces of heatshrink, on one piece make a little triagular cutout for the wire



    Desolder the switch, trim the usles pins, bed those you're about to use on the bottom on the switch, apply some tin on the pins



    Prepare the wire, tin the tips



    Solder it to the switch and put the heatshrink with the cotuot over the wire and the switch (trim of any sharp and pointy tips of excess tin to avoid penetration of the heatshrink). Use the soldering iron to shrink the heatshrink



    Place the other piece of heatshrink over rotated by 90deg. and shrink it



    Job done

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