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Thread: greenforce halogen to LED conversion

  1. #1

    Default greenforce halogen to LED conversion

    Hi guys,

    got my hands on an Arrow 12 from greenforce for very little money and thought it would be a good host to mod.
    The light head is a halogen head but I can't find any picture of this head (4 thin o-rings around the front of the head) on the internet so I'm assuming this must be one of the earliest light heads (first standard 12?) made by greenforce.

    Some dimensions:
    OD: 54mm
    total height withouth the connector at the back: 78mm
    lens thickness: 10mm
    lens diameter: 49mm
    cilindrical space under the lens: 7mm deep, ~44mm diameter, after that: conical
    available depth including conical part: ~25mm

    Anyway, the halogen bulb is dead so I pulled it out from the back of the head. The bulb is fixed to the connector at the back of the head, the reflector stays inside the head. I then removed the O-ring that keeps the lens in place. The lens is sealed by 2 o-rings around the lens so I used a wooden stick to push the lens out from the back (needed a hammer though to get it moving).
    This is the result:





    (forgot to add the reflector to the pictures, sorry)



    From the dimensions above, you can guess that his won't be a very easy mod because there is little space and it won't be easy to make a 'press-fit' heatsink.

    I'm currently thinking to just put a single XM-L or so in and making a 44mm heatsink that steps down to increase the amount of metal and to be able to drill a hole in it and put the LED in the hole but I haven't figured out how I'm going to get this done and also leaves the question of where to put the driver.

    Another idea was to make some small heatsink and make it press-fit for the hollow tube at the end of the conical part which would give me enough space for a driver and a reasonable reflector or optic, but I'm not sure if that would give me enough thermal capacity.

    A third option I'm considering is to make a video/photography head and use multiple LEDs withouth optics (less space required).... but I don't have an underwaterhouse for my camera.

    If this head doesn't work out, no problem. I have a broken HID head as well which is probably a better candidate to mod but I want to see what I can do with this head as well.

    any suggestions for a mod or clever ways to use the liitle space?

    Johan

  2. #2

    Default

    I can't guarantee it's the same GF head, but we've modded a few of the halogen ones to mr11 triple led optics. Some are easier than others. Net result is a very nice light.

    Some are real tight on the length with mr11 optic and board from cutter, and the base of the heatsink is very thin (approx 1-2mm) , but we've done it.

    For drivers I've found the shark bucks best as they're real small and fit on the underside.


    Regards,
    Damien Siviero
    http://damiensiviero.com
    Regards,
    Damien Siviero
    http://damiensiviero.com

  3. #3

    Default Re: greenforce halogen to LED conversion

    Thanks, I'll look into that. I was a bit affraid that a 1-2mm heatsink would not be able to get the heat away efficiently.

    Do you happen to have more information on the triple led optic so I can look up the dimensions?
    I'll see what I can find on Cutter.

    Johan

  4. #4
    Flashaholic* Packhorse's Avatar
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    Default Re: greenforce halogen to LED conversion

    Personally I would be very nervous about a 1-2mm heat sink and 3 XML's (assuming running at close to full power).

    If you can get a press fit heat sink into the thin tube section at the rear that should give you a excellent thermal path to the body and water.

  5. #5

    Default

    I should be clearer.

    We made one solid cylinder to fill the top part of the housing, then bored out room for the optics and mpcb. The Base was only 1-2mm but the side walls were 5-6mm and contacted the walls of the housing to give the thermal path.

    So the heatsink was quite big and contacted the housing, just didn't have a thick base. did the trick in any case.


    Regards,
    Damien Siviero
    http://damiensiviero.com
    Regards,
    Damien Siviero
    http://damiensiviero.com

  6. #6

    Default

    Just looked at you greenforce pics with more effort, looks like a different one. Ours took the mr16 bulbs, though yours looks like a burner one.


    Regards,
    Damien Siviero
    http://damiensiviero.com
    Regards,
    Damien Siviero
    http://damiensiviero.com

  7. #7

    Default Re: greenforce halogen to LED conversion

    Quote Originally Posted by Packhorse View Post
    Personally I would be very nervous about a 1-2mm heat sink and 3 XML's (assuming running at close to full power).
    yeah, me too, but I've seen some pictures in your thread that does something similar to what betti154 describes and that's what I figured could be a good sollution.

    Betti154, it is indeed not an MR16 head, as an MR16 is 2" (>50mm) in diameter, while this head only has a 45mm inner diameter.

    I checked the carclo optics. These are 6mm high, so that leaves about 1mm for a base, but the led board should also go under it.
    I suppose I'll need a 45mm disk, board out for the diameter of a tripple optic and tripple led board. (7-8mm deep, 20mm diameter). this means that I'll have to make the disk thicker than 7mm and step it down a bit where it becomes conical.

    I guess I'll need a lathe for that. I've already decided I'm getting me one, but haven't found the time to choose and get one...

    So, meanwhile, I think I'll explore the option of a press-fit heatsink in the tube at the end with an XML at 2.8A or so. The only issue with this that I can see is that it would be difficult to get the head open once everything is installed.

  8. #8

    Default Re: greenforce halogen to LED conversion

    Quote Originally Posted by Packhorse View Post
    Personally I would be very nervous about a 1-2mm heat sink and 3 XML's (assuming running at close to full power).
    yeah, me too, but I've seen some pictures in your thread that does something similar to what betti154 describes and that's what I figured could be a good sollution.

    Betti154, it is indeed not an MR16 head, as an MR16 is 2" (>50mm) in diameter, while this head only has a 45mm inner diameter.

    I checked the carclo optics. These are 6mm high, so that leaves about 1mm for a base, but the led board should also go under it.
    I suppose I'll need a 45mm disk, bored out for the diameter of a tripple optic and tripple led board. (7-8mm deep, 20mm diameter). this means that I'll have to make the disk thicker than 7mm and step it down a bit where it becomes conical.

    I guess I'll need a lathe for that. I've already decided I'm getting me one, but haven't found the time to choose and get one...

    So, meanwhile, I think I'll explore the option of a press-fit heatsink in the tube at the end with an XML at 2.8A or so. The only issue with this that I can see is that it would be difficult to get the head open once everything is installed.
    Last edited by jspeybro; 10-25-2011 at 08:59 AM.

  9. #9

    Default Re: greenforce halogen to LED conversion

    Betti154, I guess you were talking about triple XP-G boards?

    edit:
    the battery is made of 10 sub-C NiMh 3000mAh batteries in series. Not sure if that could even drive a tripple XML so for now I think I'll look for a tripple XP-G or a single XM-L.

    I'm thinking of replacing the batteries with 6000mAh ones in case the battery is damaged or old so that could give a bit extra juice.
    Last edited by jspeybro; 10-25-2011 at 01:24 PM.

  10. #10
    Flashaholic* Packhorse's Avatar
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    Default Re: greenforce halogen to LED conversion

    That being the case I am sure it would be fine.

  11. #11
    Flashaholic* Packhorse's Avatar
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    Default Re: greenforce halogen to LED conversion

    Quote Originally Posted by jspeybro View Post
    Betti154, I guess you were talking about triple XP-G boards?

    edit:
    the battery is made of 10 sub-C NiMh 3000mAh batteries in series. Not sure if that could even drive a tripple XML so for now I think I'll look for a tripple XP-G or a single XM-L.

    I'm thinking of replacing the batteries with 6000mAh ones in case the battery is damaged or old so that could give a bit extra juice.
    I have run a triple XML off a 10 x NiMh pack and it worked great. I had used a KD 2.8 amp driver.

    But you could also use a 8 AMC 7135's which I think is a great option.

  12. #12

    Default

    Xpg or XML make no difference to current draw, just light output assuming draw is the same. We've run xpg and xmls at 1200ma off the greenforce stick battery, as well as xmls at 3amp off h6flex. All depends on what burn time you want, but I know wreck guys who say and hour is plenty. I've got two primary lights with small and large battery depending on the dive duration (typically cave vs wreck).

    I'm a fan of the rcd24 and taskled drivers but as packhourse mentions there are cheaper alternatives.
    Regards,
    Damien Siviero
    http://damiensiviero.com

  13. #13

    Default Re: greenforce halogen to LED conversion

    Quote Originally Posted by Packhorse View Post
    I have run a triple XML off a 10 x NiMh pack and it worked great. I had used a KD 2.8 amp driver.

    But you could also use a 8 AMC 7135's which I think is a great option.
    isn't a AMC driver limited to about 6V input voltage? or would you put 3 boards in series and let them each drive 1 LED?

    The KD driver, can it drive multiple XM-L's (I still have some of these drivers somewhere)? I found a thread where you say you can drive 2 and maybe 3 leds in series. Since the battery voltage is about 10-12V and 3 leds in series will be about 10.5V, it might be a bit tight when the battery runs dry. someone mentionned to replace a capaciter but failed to mention which component.
    Since you already tried this, I guess it could work. I'll have a closer look.
    Last edited by jspeybro; 10-26-2011 at 02:31 AM.

  14. #14

    Default Re: greenforce halogen to LED conversion

    on the other hand, triple xml at 2.8A is a bit overkill I think since the optics will be small (6mm high) and the beam rather floody (bad thing for the Dutch waters)

  15. #15

    Default Re: greenforce halogen to LED conversion

    Quote Originally Posted by jspeybro View Post
    isn't a AMC driver limited to about 6V input voltage? or would you put 3 boards in series and let them each drive 1 LED?
    ok, I always forget this nice setup which is why I didn't understand your suggestion...

    but with XM-L instead of P7 LEDs. I suppose that could indeed be a good solution for a 12V NiMh pack and a triple XM-L

  16. #16

    Default Re: greenforce halogen to LED conversion

    The new lathe has been put to use and a heatsink was made for both the halogen head and the HID head. In the halogen head I used a tripple XPG on a 20mm star from cutter, individually addressable and connected as displayed in the previous post but with a 4xAMC7135 to provide 1400mA. The optic was the matching 20mm carclo optic.
    For the HID head I used a cree MC-E because I had this lying around and I had a nice matching 35mm TIR optic from DX that gives a nice beam. The driver is a modified 2800mA DX driver (replaced capacitor to support higher voltage input as the original only worked up to 8.4V) with the dies of the led connected in parallel. I suppose this could be upgraded in a later stage to XML but I haven't checked if the optic works well with the XML.

    I'll post some pictures when I find the time to make some.
    next on the list is putting the umbilical back together and diagnosing the battery (probably overdischarged and not charged for too much time so might need to be replaced...)

    edit: pictures

    HID head and heatsink:




    Halogen head:



    Johan
    Last edited by jspeybro; 11-17-2011 at 01:37 PM.

  17. #17

    Default Re: greenforce halogen to LED conversion

    The triple XPG setup doesn't seem to work very well... after a few seconds, the LEDs start to strobe fast and after 10-15 seconds or so, it starts to flicker. This of course indicates that the AMC chips are overheating and the thermal protection is kicking in.
    Initially it started to flicker immediately, but the driver wasn't heatsinked at all. I then used thermal glue to glue the AMC chips to the back of the heatsink, which helped for a few seconds, so this doesn't seem to be enough.

    I suppose the battery voltage when fully charged is too high (10x1.2V NiMh in series) compared to the forward voltage of the 3 LEDs, where as it might work fine with a partially discharged battery.
    Any idea if there is another way to keep the AMC chips cooler, other than sticking the package to the heatsink?
    would it help to cool the board somehow?

    Maybe I need to start looking for another driver if this AMC setup doesn't work out.

    any suggestions?

  18. #18
    Flashaholic b-bassett's Avatar
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    Default Re: greenforce halogen to LED conversion

    nice work so-far!

    with 10 x 1.2 V NiMh's thats around 15 ish V fully charged, so with a drop of approx 6.6V on 2 leds, thats still over 8 volts for a fair bit of time (depending on battery sag) id say even with better heatsinking of the chips, they wouldnt work very well.

    another led might be an idea? would work well untill the battery pack dropped to approx 13.2 V then would be un-regulated, slowly getting dimmer. though that would be a complete re-think of your optics and head arrangement. and im not sure ther will be many that fit in the sapce given

    or you could remove a cell or 2 from the pack, 8 cells would give you 9.6 nominal, so a regulated range of 12-9.9 V. minus the 6.6 gives you 5.4-3.3 V across the driver, after that your out of regulation. this may require a new charger though

    otherwise its a new driver, might be the simplest option

    myself id be tempted to try and fit a quad board + optics in there, but that may not be the best sollution (i dont personally like the empty space in the head)
    Last edited by b-bassett; 12-27-2011 at 03:16 AM.

  19. #19

    Default Re: greenforce halogen to LED conversion

    I prefer to keep it compatible with greenforce because a lot of my buddies also use greenforce.
    you mention the quad board. did you mean to use the same setup but with an additional led to drop an extra 3.3V? That sounds like a possible solution, but I'll need to check if that will fit since the optic is higher and has a bigger diameter. I'll look into that.
    Using a single LED like an XML will be difficult I think due to the (usually) larger driver.

    Johan

  20. #20
    Flashaholic b-bassett's Avatar
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    Default Re: greenforce halogen to LED conversion

    i think iv seen a 35mm quad board somwhere, maby it would fit?, not sure of the optics height though so maby not.

    perhaps 3 additionall leds (xpgs?) could be attached aruund the circumference of the current set up, put them all in parrallel then series them to the tripple already installed?
    without optics they would be all flood, but with only 450mA going through them they wouldn't add much to the heat, and might make a nice low level close up flood

  21. #21

    Default Re: greenforce halogen to LED conversion

    cutter.com.au has a 24mm quad xpg that is individually addressable so that would be suitable. It's a bit unclear though for the optic since the optic they link to is out of stock...
    They also have some MR11 quad optics for 25mm boards so they may fit the 24mm boards as well. the optic would need some grinding though to remove the outer edge that is not part of the lenses.

    I guess I'll send them an email when they are back in the office.

    once I know what optic can be used, I can check if it fits in the head with a new heatsink.

  22. #22

    Default Re: greenforce halogen to LED conversion

    a bit overdue for an update on this project...

    meanwhile, the 24mm quad XPG module with 24mm optic arrived from cutter. I made a new heatsink, similar to the triple xpg board.
    I used a AMC driver that drives 1 of the LEDs. The other LEDs are in series with the driver itself to drop the voltage.
    Since the battery has a full charge of a little over 14V, this should be a nice fit. 3x 3.25V drop=9.75V drop. Add to that the input range of the driver of about 3-5.5V, this setup should be able to cope with the voltage of the battery pack. It will however start dropping in intensity a bit sooner than I wanted, but have yet to do some tests.
    I measured a FWHM angle of 14-15°. That's a little more than I would really want, but this is still impressive for such small optics. I'll post a comparison of the intensity profiles and some info on the angle measurement in one of my next posts in this thread.
    The AMC driver is one of 1400mA with a microcontroller and stars where I connected star 2 to the ground giving me a high and a low mode, which is 100% and a little over 10% intensity.

    Currenlty I just need to get a new o-ring since one of the o-rings shows some damage and I don't want to risk a flood on my first dive with it.
    pictures will follow.

    Johan

  23. #23

    Default Re: greenforce halogen to LED conversion

    Here's a montage of beamshots I made yesterday:



    from left to right, top to bottom:
    The 4x xpg mod I mentionned in my previous post, high and low;
    the next one is another project I'm working on, using a cree xml and a 3A DX driver with a 35mm optic;
    then the other greenforce mod shown in pictures above, using also a cree xml and a 35mm optic and a 2.8A DX driver;
    the last one is a greenforce original tristar, however, this is one of the first of these heads ever made by greenforce and the intensity is really disapointing (even lower than the low mode of the quad xpg as you can see in the intensity comparison below.



    This graph gives you a nice intensity profile comparison. I thought initially that the 2 XML lights used the same optic, but apparently the 3W Hollis lights use a slightly different optic than the DX optics. The DX 35mm TIR optics are a near perfect match for cree XML leds in my opinion.
    While the quad XPG head on high has a slightly lower maximum intensity, there is clearly a lot more light and more evenly distributed in the cone of light. This graph can also be used to determine the position of the half intensity. Currenlty I used pixels of the beamshot pictures on the X-axis. I'll see if I can convert that to angles so you can more easily read the graph.

    1 difference between the 2 XML lights, is the battery. The 3A driver runs off 2 18650's, while the 2.8A driver runs off the greenforce 12V Arrow NiMh 3.3Ah battery.

    enjoy :-)
    Johan

  24. #24

    Default Re: greenforce halogen to LED conversion

    Hi Guys,

    I have some underwater beam shots of some of my greenforce mods :-)
    Sorry for the crappy quality, it's the first time I actually took a picture underwater...
    The first is the cree MCE @ 2.8A with 35mm optic:


    the second is the quad XPG @ 1.4A per LED on 24mm board with matching 24mm optic


    The 3rd is a mod that I didn't show before. It's a greenforce PRO head in which I placed a cree XML at about 2.5A and an aspheric. I'm currently using this as my primary light:

    My buddy called it my lightsaber ;-)

    Johan

  25. #25
    Enlightened Pizeer's Avatar
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    Default Re: greenforce halogen to LED conversion

    Quote Originally Posted by jspeybro View Post
    The triple XPG setup doesn't seem to work very well... after a few seconds, the LEDs start to strobe fast and after 10-15 seconds or so, it starts to flicker. This of course indicates that the AMC chips are overheating and the thermal protection is kicking in.
    Initially it started to flicker immediately, but the driver wasn't heatsinked at all. I then used thermal glue to glue the AMC chips to the back of the heatsink, which helped for a few seconds, so this doesn't seem to be enough.

    I suppose the battery voltage when fully charged is too high (10x1.2V NiMh in series) compared to the forward voltage of the 3 LEDs, where as it might work fine with a partially discharged battery.
    Any idea if there is another way to keep the AMC chips cooler, other than sticking the package to the heatsink?
    would it help to cool the board somehow?

    Maybe I need to start looking for another driver if this AMC setup doesn't work out.

    any suggestions?
    What kind of temperature are you seeing? Deg F or Deg C?

  26. #26

    Default Re: greenforce halogen to LED conversion

    Quote Originally Posted by jspeybro View Post
    The 3rd is a mod that I didn't show before. It's a greenforce PRO head in which I placed a cree XML at about 2.5A and an aspheric. I'm currently using this as my primary light:
    ....
    My buddy called it my lightsaber ;-)

    Johan

    Hello Johan,
    what kind of aspheric are u using with the xml, i like the beam

  27. #27

    Default Re: greenforce halogen to LED conversion

    Quote Originally Posted by Pizeer View Post
    What kind of temperature are you seeing? Deg F or Deg C?
    I have no idea. I since replaced the setup with 4 XPG's so there are now 3 XPG's in series with the driver instead of 2. The voltage drop when fully charged is now OK, and although I haven't reached this point yet, I'm guessing it will go a bit out of regulation when the battery is nearly empty.
    Basically the AMC chips had to burn too much voltage into heat, causing the temp protection to kick in. I think the set point for this system is somewhere in the datasheet, so that is probably the temperature that I was getting...

    Are you trying someting similar?

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