# Building an LED floodlight



## 96TL (Oct 25, 2007)

I have 55 watt halogen flood lights on my boat. I've been waiting for a company to finally make marine LED flood lights, but I'm getting tired of waiting. Do you think it would be possible to build my own using my halogen housings? Maybe I can mount a few SSC's or CREE's in there?

What do you guys think? This is one of the lights. They're 5"x3" or so.


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## Ken_McE (Oct 25, 2007)

Is that a metal housing you could use to sink heat?


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## Erasmus (Oct 27, 2007)

Can you give the measurements of the housing? Anyway I think it is better to use a Cree XR-E since they have a 90 degree beam which is perfect for making floodlights. The SSC P4 has a beam of around 132 degree which makes it less suitable for floodlights because a lot of light goes where you don't need it.


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## mahoney (Oct 28, 2007)

It's going to take a lot of Crees to equal the output of a 55 watt floodlight. Probably more than will fit in that housing if they are on stars. You could really cram the emitters close together and fit in enough, but then heatsinking will be a problem.


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## Calina (Oct 29, 2007)

mahoney said:


> It's going to take a lot of Crees to equal the output of a 55 watt floodlight. Probably more than will fit in that housing if they are on stars. You could really cram the emitters close together and fit in enough, but then heatsinking will be a problem.


 
Assuming 20 lumens/W for the halogen light (I'm being generous here), you will need no more than 5 Crees at 1A for an equivalent light output. Very "doable".


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## Juctuc (Oct 29, 2007)

I thinks its not wise to compare just lumens between these two lights.More than half of the lightoutput from the halogen-bulb is going to wrong direction.If you put LEDs in it, the light is coming directly from the fixture.

With LEDs you will get more light for the boat as well.With halogen some of the light is going to the sea,because of the beam.There is no use for the high lumens,if those lumens are in the wrong place.


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## ambientmind (Oct 29, 2007)

my idea would be to gut the housing, cut a piece of 1/4"-1/2" thick aluminum to fit inside the housing, then use sku 2982 from kaidoman.com to power 3 crees in series, with a total of 6 crees in each housing(two drivers in each housing). Mount the leds to the aluminum with arctic alumina adhesive, then seal the whole thing up real good and man the decks! with 6 p4s running at 755ma, that would be about 780 lumens out of each light....more than enough to see! here is a quick drawing of what i'm thinking-


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## 96TL (Oct 29, 2007)

Hmm, good plan Ambientmind. Better than what I've been trying to figure out myself so far! 6 per light should be pretty bright I think.

Wheres the best place to get the CREEs from? KaiDomain? I don't really know where to get the raw parts. This will be my first DIY LED project.

BTW, the housing is all plastic.

Thanks guys!

Dom


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## 96TL (Oct 29, 2007)

Ambientmind, would I have to mount each CREE into an individual reflector?


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## ambientmind (Oct 29, 2007)

for cheaper parts, i would recommend either kaidomain or dealextreme. i've ordered lots and lots of products from both, and really haven't had any issues with either. shipping does take some time, as the products are coming from hong kong. you wouldnt need the reflectors for a floodlight, but if you wanted some "throw" from this light, then you would need them. a bare cree will emit light in about a 90 degree angle from the emitter, so you will get a nice flood out of it, but not much throw. if you wanted to make a spotlight out of those housings, you could get the 24mm aluminum reflectors or the cree colaminating lenses from kai to put over the leds. just be sure to mount the leds as close together as possible to get a decent spot in this setup.


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## 96TL (Oct 29, 2007)

I dont think I need the reflectors. Nevermind.

Hmm. Should I go with Q5s? Double the price of Q2s.


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## ambientmind (Oct 29, 2007)

i dont think i would bother but its up to you. you might not even see a difference since the q5s need a higher vf from the driver than a q2 does. i would save the money and just go with a q2.


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## 96TL (Oct 29, 2007)

Got it. Thanks Ambient.


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## ambientmind (Oct 29, 2007)

no problem, let me know how it all works out!


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## Gomer (Oct 30, 2007)

Cree has a natural spread of about 90deg full angle. Are there any optics for ~40-50deg full angle for a Cree? This would sort of be the gap fill from full flood to spot.


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## 96TL (Oct 31, 2007)

Do you guys think I should use emitters or stars for this project? Maybe if I go with emitters I can squeeze in 2 more LEDs. These floodlights are pretty thick. I could probably use a thicker piece of aluminum than normal for the heat sink.


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## ambientmind (Nov 1, 2007)

soldering directly to the emitter is going to be a pain, the contacts are tiny! also, you would need to isolate the bottom of the emitter from the heatsink as there are contacts on the bottom too. i would use stars. you can always shave the stars down to get them smaller.


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## Erasmus (Nov 1, 2007)

ambientmind said:


> soldering directly to the emitter is going to be a pain, the contacts are tiny! also, you would need to isolate the bottom of the emitter from the heatsink as there are contacts on the bottom too. i would use stars. you can always shave the stars down to get them smaller.


Soldering a Cree emitter is not really a PITA, it just needs a little of prudence if you haven't done it before. Isolating isn't necessary either, just snip the corners of the emitter. Then contain the leads that connect the upside of the emitter to the bottom pads. Snip them and the bottom is isolated. Then connect them on the heatsink with Arctic Silver Thermal Adhesive and the thermal resistance will be very low, resulting in heatsinking which allows to drive upto 1200 mA constantly (depending on the size of the heatsink and the air flow of course). 

96TL, what is the depth of the light? I can supply aluminum heatsinks which are almost 1 inch thick for a really cheap price, just drop me a PM if you're interested.

By the way, I'd drop in one red LED among the whites, you'll see a noticeable improvement in the color rendering of illuminated objects.


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## 96TL (Nov 1, 2007)

I think I will try my luck with just the emitters. I'm not too bad at soldering.

Erasmus, I haven't removed the flood lights yet, but I will soon. When I get them gutted and take some measurements I will PM you.

Thanks guys.


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