# Homemade LED fishing light



## Craig1 (Jun 6, 2013)

Hello,

I'd like to share my homemade fishing light. I recently was invited by my uncle to go fishing at night. Prior to the trip he mentioned the lights and described them to me. Being the LED aficionado I am it was straight to Google to see said light. I couldn't believe the price. $375 or more for HID and $200-300 for LEDs. I said self you can make something comparable for a fraction. Fire up SolidWorks and more Goggling.

On the first trip i whipped together a light using 8 1206 SMDs. Very tiny and a pain in the tail to solder. We did attract a fish with it. It was a 3 inch needle fish with a diameter of oh lets see.... butchers twine. BUT IT WORKED. I did also manage to catch a 3 1/2 foot bull shark not with the lights. We were fishing in the Indian River in Northern Brevard Co. From our spot you could see the Vehicle Assembly Building at the Kennedy Space Center. 

http://i618.photobucket.com/albums/tt261/craigpat/Oh the lights/8120dSMDat5V.jpg


http://i618.photobucket.com/albums/tt261/craigpat/Oh the lights/BullShark.jpg

I purchased 25 10 watt 1000 ma green emitters. In this version 12 are being used. Holes were drilled and tapped into the aluminum for 
4-40 SS machine screws evenly spaced. The aluminum will act as a heat sink. The module with be attached to the eyelet through the cap and waterproofed along with the wire through its own hole. This will run to an alternate battery on the boat. 

Needing the light to be under water presents a problem with the bottle. I will epoxy egg sinkers to the inner bottom of the bottle. Then fill with mineral oil leaving head space for thermal expansion. The mineral oil will assist with cooling by carrying the heat from the emitter> oil> bottle> water. It will also solve the bouyancy issue. A float will be attached to the rope/wire to hold the light ~3' down in the water column. 



http://i618.photobucket.com/albums/tt261/craigpat/Oh the lights/ModuleandBottle.jpg

http://i618.photobucket.com/albums/tt261/craigpat/Oh the lights/15Feetaway.jpg



http://i618.photobucket.com/albums/tt261/craigpat/Oh the lights/100feet.jpg
Tomorrow will be the test in murky water her in Florida's inter coastal waters. I believe my cost is about $50-60.00. My Uncle is impressed and itching to try it out.

I do have questions regarding the power consumption and using resisters.

Do i require a resister? In the pictures the light is running off of a 12v 1.5a bench supply with no resisters. 

I believe i have calculated the wattage correctly. Please check my math. 12 v x 12 a consumption 144 watts ??? Yes - No Anyone?
The wiring is in parallel. All positives are connected together as well as negatives.

Regards, Craig

Parts list
-12 LEDs 10w 1000ma ~ $11.00 per 5
-Clear Nalgene water bottle ~$5.00
-1 X 1 X 6.5" aluminum thick wall tube ~$6.00 for 2.5'
-12 4-40 SS machine screws 
-Brass buss wire ~$7.00 (what I had on hand) 
-Mineral oil
-Wire 
-Rope
-SS threaded eyes
-battery clips


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## D2000 (Jun 7, 2013)

Can't wait to see how this pans out. I like the look of it so far and your build seems solid.

get some shots in the water ASAP


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## Norm (Jun 7, 2013)

Edit the OP has not returned to tend to his thread and resize images, Images now converted to links.

Your images are oversize, when you post an image please remember Rule #3 

Rule #3 If you post an image in your post, please downsize the image to no larger than 800 x 800 pixels.

*Please resize and repost.* - Thanks Norm


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## Illum (Jun 7, 2013)

Mineral Oil when sitting still has more insulating properties than thermal relief though. 

1" x 6" aluminum flat bar won't be able to accommodate more than one 1000mA LED without flying past 200F in a hurry, my experience was such driving CREE XPGs at 1000mA under natural air convection. The resulting heat discolored the drywall the aluminum bar happened to be mounted on. I'm not sure if your LEDs can survive with twelve on one square tube dipped in mineral oil sitting still. Nice approach though, interesting to see if it works out for you.


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## Steve K (Jun 8, 2013)

Count me as someone concerned about the heatsinking too. 120 watts is a huge amount of heat to get rid of in air, but if you can establish a good thermal path from the LEDs to the water, you might get by with a modest heatsink. I'd suggest figuring out how to get that aluminum shaft extended out of the cap of the bottle so you mount a modest heatsink on it. The challenge will be getting everything sealed up properly. 

As an electrical engineer, I love tinkering around with LED lights, but it seems like most of the challenge ends up being the packaging (like this one). Good luck!


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## DIWdiver (Jun 9, 2013)

Yeah, the thermal conductivity of mineral oil SUCKS. Even glass is 8x better. I did a quick and very crude estimate of the equilibrium temperature of your bar, and it came out over 1000C. If nothing else failed first, that would melt the bar, so clearly not good! 

The thermal conductivity of aluminum is 1200x better than mineral oil, so I estimated the temp if you extend the bar into the water on both ends. In this case there would be a hot spot in the middle of the bar (actually, the whole distance between the middle two LEDs). The number came out 69C above water temp. This is very near the boundary of what's acceptable and what's not, so I'd want to do a more careful calculation before I decided it would be okay or not. 

By the way, oil is several times better than air.


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## JohnR66 (Jun 10, 2013)

The oil should convect a lot of heat as long as that light is kept underwater. I would monitor the heatsink temp with a thermometer probe.


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## AnAppleSnail (Jun 10, 2013)

Do you need the jar? Low-voltage electronics don't do much in water besides rust. I bet if you dip the whole bar in epoxy and hang it to dry it'll be waterproof and cool easily enough.


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## Steve K (Jun 10, 2013)

having worked with potting material over the years, this gives me the heebie-jeebies! Potting requires a lot of attention to actually get it to stick reliably to what it is supposed to stick to. Combine that with the thermal cycling that will be happening, and my guess is that the epoxy will quickly start to pull away from the LEDs and aluminum, and/or will start to develop cracks. 

Since this light is dissipating 120 watts, applying an insulating layer of epoxy over a heatsink that is already small is asking for trouble .... IMHO, of course.


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## Illum (Jun 10, 2013)

There's always a "redneck" solution that will work, just not pretty. Recalling what I did in 2006ish for a homemade fish light. three 520nm CREE XR-Es on each face [Anyone remember XR-Es?] and ran it off using massive salvaged wirewounds. Install LEDs on an aluminum square, then after the LEDs are thermally epoxied [thermal grease and bolt won't work for this] check your connections because there's no second chances, spray on a thick layer using LED Seal or Ducky covering all the contacts. Note that where the seal touches eliminates aluminum's ability to transfer heat, therefore do not put your LEDs in one long line across all four sides, stagger them and don't spray over the entire aluminum surface. 

If you feel the heatsink is not enough [if your light doesn't feel like an anchor at 120W, you probably don't have enough heatsink] mount/bolt/weld your aluminum body to more aluminum down below. It will be more stable but take care where you put it when you're out to sea. Mine snagged on something and the line crimp that connected my lamp to my battery corroded through and left my lamp on the bottom of the channel. Without the 1/8" spring lift cable, the 20AWG power lines yanked the strain relief out and snapped on the way up. 

If anyone down here plans on scuba diving at Sebastian Inlet State Park and you find an aluminum bird feeder contraption with LEDs on it, its mine. It was built when CREE XREs first came out, there's alot of history in it. I would build another but I gave up fishing once I left high school on my way to college. My boat [or whats left of it] is likely still sitting at my old house. Its probably corroded beyond recognition by now.


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