3 Watt High Powered LED Underwater Transom Mount Fishing Light

Discussion in 'General Electronics Chat' started by mattepps717, Jan 20, 2014.

  1. mattepps717

    Thread Starter Member

    Jan 20, 2014
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    Hello All,

    I just joined the site. After visiting 50+ sites, I stopped here after reading the wealth of knowledge from community members. I hope to frequent and have many posts and comments in the future. I have a background as a store manager at Radio Shack for 8 years, and car stereo industry for 15 years. Remote starters, stereo systems, etc. I have a knowledge in building relays, resisters, diodes, etc. I am hoping I can contribute in the future to the community.

    I read a number of the posts and responses before starting my own thread, not to hi-jack a previous post.

    I am needing some help with an LED diagram for a small project. I am building an underwater LED transom (Boat) mounted light. I have seen dozens of these all of the internet, for $500 to over $1,000 each. Ridiculous when you consider the materials to build one yourself. I've spent the last 3 months researching the type of enclosure and materials and making my purchases across the globe to be shipped in.

    [​IMG]


    GOAL: Build two 24 LED (72 watt) transom light in GREEN and two more in BLUE. Optical grade epoxy potting, encapsulating the LED's and all connections for waterproofing. Large block corrosion resistant heatsink + thermal paste for heat dissipation. 30 foot Teflon coated wire to switch, battery terminal.

    This gentleman at loomisLED has created exactly what I hope to accomplish. He states he is an MIT graduate, with 25 years of experience. He states his light has no special drivers or components, but driven only by the length of the wire (35 ft). 30,000 hours of life on the LED's. He hand builds these lights in his workshop and sells to the public. The light cannot be run out of the water for more than 4 minutes, for cooling purposes. Claims it has been tested in 100 degree salt water.

    [​IMG]

    http://loomisled.com/shop/2-24-led-flush-mount-boat-transom-lights-12-14-5-vdc-charging-battery/

    THE PROBLEM: As you all know, voltage on a boat/auto can fluctuate from 11.4V to 13.5V when the engine is running, alternator charging the battery. I like the idea of no components, the enclosure will be completely sealed and encapsulated with no access to components. Should a resister burn out, or voltage regulator fail, I would be destroying the sealed enclosure to replace the failed component.

    I would like to wire 3 rows of 8 on the circuit, similar to the picture of the example above. I have read some of the posts by SgtWookie recommending the Buckpuck.

    The LED Specs are as follows:

    3w:

    [COLOR=#ef00fd]700mA [/COLOR]
    [B]green:[/B][COLOR=black][COLOR=#002cfd]DC Forward Voltage:3.4V~3.8V [/COLOR][COLOR=black][COLOR=#ef00fd]Forward Current: 600-700mA[/COLOR][/COLOR][/COLOR]
    [COLOR=black][COLOR=black][COLOR=#ef00fd][COLOR=black]blue:[COLOR=black][COLOR=#002cfd]DC Forward Voltage:3.6V~3.8V [/COLOR][COLOR=black][COLOR=#ef00fd]Forward Current: 600-700mA[/COLOR][/COLOR][/COLOR][/COLOR][/COLOR][/COLOR][/COLOR]
    [COLOR=black][COLOR=black][COLOR=black][COLOR=black][COLOR=black]Green 510~530 nw[/COLOR][/COLOR][/COLOR][/COLOR][/COLOR]
    [COLOR=black][COLOR=black][COLOR=black][COLOR=black][COLOR=black]Blue 460~475 nw[/COLOR][/COLOR][/COLOR][/COLOR][/COLOR]

    Any input or recommendations to my build would be much appreciated. I hope to post pictures of the progress. Maybe the project build can earn a "Sticky" later
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Just a few ideas:
    1) Minimize the amount of stuff that must be sealed and cannot be repaired. I'm thinking for instance that you should place any circuitry on the power end of the wire as opposed to the LED end.
    2) Boat and auto electrical systems are notoriously noisy with spikes and transients. I think it would be wise to build an isolated supply that filters out that noise and sends your LEDs a nice steady voltage.
    3) To prolong the LED life, something to consider is running them well below their current rating. Just add a few more if you need more brightness.
     
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Just a couple:

    I think they are in 8 rows of 3. The 3 being in series. Then 8 in parallel.
    You will need to buy matched or binned leds since you are going to run them in series parallel without resistors or regulators.
    I'm not sure how they get away with no current limiting except the wire. I make it to be at least 26 AWG which would make 25 feet of it .35 ohms. Maybe they found some LEDs with high Vf. But you could put 1 ohm under the dash?
    How will your heat sink work?
     
  4. wayneh

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    Sep 9, 2010
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    I count just 6 rows (columns?) but I agree that it appears to be 3 in series. That's the only arrangement that makes sense, as well.

    Six at 600mA is 3.6A, so it is plausible that the wire alone is dropping over 1V. That's not how I would do it, but maybe that says more about me.
     
  5. mattepps717

    Thread Starter Member

    Jan 20, 2014
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    Thanks wayneh, the picture is what someone built for an 18 LED setup. I just posted it for demonstration purposes. He uses a 24 LED setup, which I will be duplicating in my rectangular enclosure instead of the round he used. I am open for some alternative suggestions. I am not opposed to adding a driver, I just want to be able to seal up the enclosure. In parallel I suppose, and can add a driver at the end of the 30 foot run of wire in a dry location. ​
    Here is the 24 LED (8 x 3 rows) that I would like to build, in my enclosure.​
    [​IMG]
    Any suggestions on a specific driver, hookup connections or wiring on the dry end would be much appreciated!​
    ronv, I agree a small AWG wire, and length for the voltage drop. The heatsink will be inside the enclosure, heatsink paste on the other side of the aluminum mounting plate. The Bead LED's will actually embed in the Thermal heatsink compound, then clear epoxy over it.​
     
  6. wayneh

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    Sep 9, 2010
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    I'm not convinced you need a "driver" so much as a filter. For instance a 15V zener diode to catch voltage spikes? There was a thread here once on how to condition an automotive supply for sensitive electronics but I can't recall what was in it.
     
  7. mattepps717

    Thread Starter Member

    Jan 20, 2014
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    I see, to act as somewhat of an inline low voltage surge protector.

    So, if you could help me with the technical logistics. Based on the type of LED's that I am using above. What length of wire and configuration of soldering the LEDs would you recommend to drop the voltage to the specifications on the 24 LEDs. I don't want to over power them and fry the LEDs, but still enough to get the most lumens out of the setup?

    I do like the buckpuck that incorporates a potentiometer, that could dim the light. But if you think it can be done without it, I will.
     
    Last edited: Jan 20, 2014
  8. ronv

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  9. mattepps717

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    Jan 20, 2014
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    Yeah, that is a little pricey. I buy a lot from China, I'd hate to see that price in the US.

    So, I would be willing to make a donation for anyone who can help me with my project.
     
  10. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Do you know if the housing was tested at depth? And is it rated for dynamic pressure? Many of the UW watches, cameras etc you see will have a depth rating but it is usually in static pressure.

    But dynamic pressure will exceed static pressure.

    Before you spend too much time and money on your project you should consider doing thorough testing under actual conditions on your housing. Make sure there are no leaks.

    A light in a marine environment, especially a UW one will suffer a significant amount of abuse. That probably justifies why the purchased ones cost so much.
     
  11. mattepps717

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    Jan 20, 2014
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    Hello spinnaker, that is an excellent question. I have had the case submerged in a bucket of water for about 5 weeks, with no signs of leaks. The case itself will be no more than a foot below the waterline, so it should be fine. The clear cover is UV resistant and fade resistant to light. Most recommend a thin layer of Vaseline on the exterior glass to avoid marine growth.

    I contacted the enclosure manufacture "Polycase" (MADE IN THE USA) and explained my project. They said it will be fine, waterproof and should expect no issues.

    http://www.polycase.com/ml-47f-1508

    So far so good.
     
  12. ronv

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    The buck puck is neat, but it can only drop the voltage and needs a couple of volts over the output voltage to regulate. You need at least 3 LEDs in series for them to share well so you need almost the whole 12 volts. No room for the buck puck.
    I, like Wayneh would like to see a little resistance besides just the wire. If we shoot for 700 ma at 14.6 volts and use 8 sets of 3 that would be 5.6 amps. At 3.7 volts each for the LEDs (11.1 volts for each set) we need to drop 4.5 volts @ 5.6 amps for a total resistance of .8 ohms. So we could probably use 2 1 ohm 15 watt resistors in parallel and count on the wire for the rest. This may be a little disappointing when the motor is not running and you only have the battery voltage to work with.
    If you use the little supply I posted you can use 3, 4, 6, or 8 in series and just adjust the maximum current accordingly. 5.6, 4.2, 2,8 or 2.1 amps. It will be the same brightness no mater what the battery voltage is.
     
  13. ronv

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  14. mattepps717

    Thread Starter Member

    Jan 20, 2014
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    That is a better price ronv. Some resisters on the dry end of the wire, to get the MA under the manufactures threshold. If I could get it around 600 ma, would be best, instead of at max handling.

    I do have 4 batteries on the boat, so I could bump up the current on an isolated circuit to 24v or 36v if necessary. The light will be running mostly when still, engine off. However running across the water with lights on would be great too.

    Let me work up a schematic diagram and you all can help me tweak it, before I build a prototype.
     
  15. wayneh

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    Sep 9, 2010
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    That's a remarkable device for the price. Amazing. I like the idea of boosting up the voltage to reduce the total current, although the downside is that more LEDs go out when any one string goes out. I guess these LEDs fail to open?
     
  16. wayneh

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    Did they understand the issue Spinnaker was raising? Hitting a wave and then crashing down at 40mph can cause some very large dynamic pressures. Or bumping a log or an unplanned "beaching". Doo doo happens. Just look at the hull of my Sea-Doo. :rolleyes:
     
  17. mattepps717

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    Jan 20, 2014
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    Ha ha... that is s good point. I missed that earlier. Although encapsulating the LED's may protect it from elements, if I haphazardly back into a dock, or trailering the boat down the road "pothole"! Like jarring the filament in a 60 watt incandescant bulb, I may be rebuilding a light sooner rather than later. I suppose time will tell. I could live with that, and find a higher quality LED. I just want to get the wiring MA, and voltage correct on the wiring.
     
  18. ronv

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    If you have 24 volts available you could use the buckpuck.
     
  19. ronv

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    Must be time to go to bed. :rolleyes: You can only run 1 string with the buck puck.
     
  20. mattepps717

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    Jan 20, 2014
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    Here's what I have so far...

    [​IMG]
     
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