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Thread: 2x P7 Light

  1. #1
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    2x P7 Light

    I wanna get into some night riding so.. Im obviously gonna need a light. I saw EL34's Triple P7 build and figured I could build something identical only smaller. I drew it all up in CAD and it looks swell. Problem being, I have no idea what I need hardware wise, other than the LEDs themselves.

    Reflectors or lenses?
    What driver?
    Can I use a 7.4v R/C Car battery?

    The machining and designing part I can handle fine, but the electronics part... not so much. I can solder though. Think I could get one of you to make me a parts list? I like different power settings, maybe a flash mode too. What more do you need to know?

  2. #2
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    If you are after a few power settings and flash then check out TasLED drivers:
    http://www.taskled.com/

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    Being your first post...I'm gonna jump in and tell you to browse this forum for a few days, then come back with any questions.

    P7's arent bad by any means, but there are loads more options. Just read through some threads, especially all of the ones that are like "first build" or "completed light" etc.

  4. #4
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    Oh and you have to show us something you have machined already....so we know what to expect..
    Serious its in the mtbr rules

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    here is the cad drawing of what i designed. Figured it would be easier and less time consuming to do it all out of .125 aluminum rather than billet.

    The outer case is .125" Alu with .0625" ribbing milled in and a .0625"x.03" lip for the lexan window. Also has the half lap joint like EL34's.


  6. #6
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    I'll jump in also.
    I like your CAD drawing.

    P7's will require huge amounts of current, so don't cheap out on the batteries.

    On single P7's, I run 3.7 volt packs (4 x 18650's in parallel)
    On my triple P7, I run 7 x 18650's in a water bottle cage pack.

    I run my lights at 3.6 - 3.7volts with simple current limiter driver boards.
    (The P7 tiple is direct drive, no drivers)

    New 18650's is what I would use if you are going to use P7's and try to run tham at +2.5 amps each

    I have been thrilled with the performance of my triple P7 this year.
    Sold my double P7 handle bar set to a friend the first time I used the Triple.

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    If I went with (2) SSC P7's and (6) 18650 batteries wired in ???, What driver would you recommend? I am ok with just 1 setting, I doubt I would use more settings if I had them. Kind of like having a 1000hp daily driver, sure it'll be cool, but you'll never use it all.

    Secondly, I am still lost on what reflectors will or will not work with this led.

    will this one work?
    http://www.dealextreme.com/details.dx/sku.14599

  8. #8
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    Others may be able to help with driver suggestions.


    I only use the 7135 chip current limiter boards with parallel battery packs, which is a very simple setup.
    As you have probably already seen on my web site, you can turn one board on for 1400ma or two boards in parallel for the max current. Basically a nice high and low, which is all I need and like.

    The sku 14599 DX reflector you linked to is the one I use in all my builds.

    It does not fit a P7, it has to be machined.
    The threads have to be removed and the hole has to be enlarged.
    I sell them already machined on my web site.
    I really like the beam shape of that reflector so that is why I use it.
    Also, it is 35mm diameter and so it drops right into Marwi housings.
    Last edited by El34; 01-09-2011 at 05:09 AM.

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    I am trying to figure out my runtime based off of (2) P7's ran of (6) 18650's in parallel. 3.6v @ 2,500mAh...

    2 led x 3.3v x 2.8A = 18.48w

    6 cells x 3.7v x 2.5A = 55.5w/h

    3 hrs run time?

    Am I right?

  11. #11
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    You don't have to go through all wattage calc stuff.

    Say you run the P7 at 2.5 amps or 2500 milliamps

    You have one battery rated at 2500 mah

    That's one hour run time in theory.

    I like to add one cell to the pack and call run time one less than the number of cells, just for safety.

    3 x 18650 cells (2500mah) are 3 hour run time in theory but add one more to the pack for good measure and some cushion.

  12. #12
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    El, do you have beam shots of that reflector anywhere?

  13. #13
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    P7 on Low


    P7 on High

  14. #14
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    Thanks Jcrazy,
    Yes those two shots show how smooth and even the beam shape of that reflector is on a gravel road.

    It's hard to tell how far the throw is, but check out the animation.gif file below

    It shows the two still photo's above, then the 3rd photo is my triple P7.
    https://www.el34world.com/Misc/bike/BikesLights49.htm

    You can see the tree that is 150ft out on the road bend in the triple P7 shot and it is barely visible in the other shots.
    It gives more depth perception to the 3 beam shots.

    Beam shot animation file - wait for the animation to load and then it will play in a loop
    https://www.el34world.com/Misc/bike/...7Animation.gif

  15. #15
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    2 of these http://www.dealextreme.com/details.dx/sku.12721
    1 (2-pack) of these http://www.dealextreme.com/details.dx/sku.14599
    4 (2-pack) of these http://www.dealextreme.com/details.dx/sku.5790
    1 of these http://www.dealextreme.com/details.dx/sku.20330
    1 of these http://www.dealextreme.com/details.dx/sku.6105 (i think, is there a better alternative?)
    1 of these http://www.dealextreme.com/details.dx/sku.32751

    still havent decided on the switch and stuff as i cant find em on DX. i think ill just visit Radioshack or something when the time comes to build.
    Last edited by jcrazyjj; 01-17-2011 at 05:46 PM.

  16. #16
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    sku. 32751 is TOO thin for 3A, IMO.
    I use it in my double XPG light (so, it's only 2A), and the wire gets quite warm = crap.

  17. #17
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    Quote Originally Posted by klynk
    sku. 32751 is TOO thin for 3A, IMO.
    I use it in my double XPG light (so, it's only 2A), and the wire gets quite warm = crap.
    is there another product you can suggest?

    also, if you could only have 1 light, would it be a helmet or handlebar light?

  18. #18
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    Helmet

  19. #19
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    Quote Originally Posted by jcrazyjj
    is there another product you can suggest?
    also, if you could only have 1 light, would it be a helmet or handlebar light?
    Helmet light, IMO.
    I suggest making cable by yourself - you need 20 AWG wire and some MS-style plugs.

  20. #20
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    Quote Originally Posted by klynk
    Helmet light, IMO.
    I suggest making cable by yourself - you need 20 AWG wire and some MS-style plugs.
    best place to buy these? i looked at DX and google but didnt come up with much.

  21. #21
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    jcrazyjj
    Honestly I don't know - maybe rs-online or something similar.
    I bought a pair of 2.1x5.5 mm power plugs (Magicshine compatible) in my local electronics/parts shop.

  22. #22
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    This was put on the back burner because of some unexpected expenses that came up. I've decided to go to 1 P7 opposed to the 2 because Im only gonna use this light when daylight is dying and I don't plan on riding at 2am anyway, so I don't need 1500 lumens...

    I want to do 1 P7, either on or off. NO other settings. I DON'T want them. Probably a 4P battery pack as well. What kind of driver do I need? The more simple the set up, the better.

  23. #23
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    and is there an led out there that i can get more lumens out of for the same power consumption?

  24. #24
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    Xml T6

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    Hiya klynk, I recently got some of the dx connectors you mentioned problems with in post #16. Mine have about 25 conductors (and I'm guessing 0.2mm wires), and a diameter (when twisted) of about 1mm. Have you cut into any of yours to know if they're like these? (If they are, I'm a little concerned...)

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

  27. #27
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    Quote Originally Posted by jcrazyjj
    I want to do 1 P7, either on or off. NO other settings. I DON'T want them. Probably a 4P battery pack as well. What kind of driver do I need? The more simple the set up, the better.
    Well, the simplest way to run one P7 from a parallel-only pack is direct drive - that is with no driver at all, simply a resistor. Yes, when the cells are freshly charged you'll be driving the LED hard (so reduced runtime because of increased current) and yes, it will dim as the cells run down. However it is perfectly functional and I've used a direct drive single P7 flashlight on the bike many a time.

  28. #28
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    so... if i get this. What do I need to get like a 2hr run time? Also, reflectors for the XML?
    Last edited by jcrazyjj; 04-05-2011 at 08:02 PM.

  29. #29
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    I run my triple P7 light direct drive off of a 7 x 18650 pack - all batteries in parallel.

    The current of the light is over 7.5 amps when fully charged, which means each P7 is pulling around 2.5 amps.

    There is enough resistance in the wire + solder joints + switch contacts + connectors to make a very low value resistor.

    No driver electronics needed in this case as the P7's are not being overdriven.

    However, I have seen P7's pull over 3.2 amps in direct drive mode
    And only for a short time when the pack is fresh.

  30. #30
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    If I did a 4P battery pack at 10,000mAh and this LED. How would/should I wire it up?

  31. #31
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    Quote Originally Posted by jcrazyjj
    If I did a 4P battery pack at 10,000mAh and this LED. How would/should I wire it up?
    With an Lflex from taskled.
    I WANT TO BUY YOUR MAGICSHINE LIGHTS! Working or not.

  32. #32
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    Quote Originally Posted by BKruahnndon
    With an Lflex from taskled.
    thats exactly what i am trying no to do.

  33. #33
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    Quote Originally Posted by jcrazyjj
    thats exactly what i am trying no to do.
    Explain.

  34. #34
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    i want to know if there is a way to direct drive these without buying a driver. all i want is full on or full off. nothing else. id rather not spend the $30 on a driver just to have those settings.

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    You know the main purpose of the driver is not to give you modes? if you don't want to spend the money, then what about a cheap and cheerful driver from dx without modes? -

    http://www.dealextreme.com/p/regulat...ax-input-20330

  36. #36
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    i like that.

  37. #37
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    Just don't expect to get 3 amp from it.

  38. #38
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    Quote Originally Posted by MrLee
    You know the main purpose of the driver is not to give you modes? if you don't want to spend the money, then what about a cheap and cheerful driver from dx without modes? -

    http://www.dealextreme.com/p/regulat...ax-input-20330

    Order at least three of those if you want one functional. I works with MC-E, but puts out only 1.8A. I tried one with XM-L and it went silent.

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