# Waterproofing COB LED



## RJN (Mar 23, 2016)

Hi everyone, new member here. I'm looking to build a flounder gigging light similar to one I bought. My only question is regarding how to waterproof the COB chip itself (e.g. silicone, epoxy, etc.) so that it can be submerged in saltwater. Any suggested products would be greatly appreciated. The light I have is mounted to an aluminum heatsink embedded in clear silicone or epoxy. The material isn't rock hard but almost feels rubbery. Thank you for any help.

Also, do you have to have a subscription to post a picture saved from your computer?


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## FRITZHID (Mar 23, 2016)

To post pictures you need a hosting site like Photobucket


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## RJN (Mar 23, 2016)

Here is a picture of what I'm trying to accomplish;




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## Steve K (Mar 23, 2016)

I seem to recall someone wanting to pot some LEDs for an underwater light, but it was years ago. You might want to search for terms such as "optically clear encapsulant". 

The alternative is to build a waterproof housing around the LED, similar to what is done for dive lights. The closest that I get to this sort of thing is making bicycle lights that are sealed from weather/rain/snow. Well, I have also designed electronics that had to survive immersion in a meter of water. Stuff like Loctite 5900 is a good sealant between a housing and a lid. It might also work between the housing and a plexiglass cover. 

and in case it's not obvious, it's best to test the waterproofness of a housing before you actually install the electronics. It's much cheaper in the event that it didn't seal properly.


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## mcnair55 (Mar 23, 2016)

My idea would be to coat the finished item in electrical lacquer.For a living part of my portfolio of workshop consumable goods is a 3 part professional use system of a cleaner,sealer and a lacquer to waterproof the finished job.We sell it in high water risk areas such as chiller/freezer trailers for trucks and another good use is in a milking parlour.


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## RJN (Mar 24, 2016)

Thanks for the replies. I've been looking at some of the potting and encapsulation compounds, but it looks like they're going to be pretty expensive for the amount that I would need to completely cast the led. I doubt that the maker of these lights is using a compound that costs 5x what the Chinese led cost (assuming it's Chinese).

Also, these lights are advertised as "30w" and are able to operate directly from a 12v battery without a driver or any external circuitry. Unless I don't understand the math at all, 30/12=2.5a. I have run this light for about 6 hours without any noticeable dimming on a 12v 8ah battery. Anyway, has anyone seen chips like these that are able to be powered directly from a 12vdc battery without a driver?


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## Steve K (Mar 29, 2016)

Not sure what to tell you about waterproofing. Potting and encapsulants tend to be rather pricey. 

As for the LED being able to be hooked directly up to a 12V battery... my guess is that the LED's forward voltage is roughly 12V... i.e. it just starts to conduct somewhere around 12V. As you note, if you are running the light for 6 hours from a 8Ahr battery, then you sure aren't drawing 2.5A. I would guess it is closer to 1 ampere. It might be fun to connect a meter in series with the LED and measure the current.

In general, it's nice to have something that will limit the current to a safe level over the full range of the applied voltage. Assuming that you are using a lead-acid battery, they will generally be 13.5VDC or so when fully charged, and can run down to .... 11V or 10V? You might benefit from adding a resistor in series with the LED in order to keep it safe with a fully charged battery. A rough estimate would be 0.5 ohms, and rated for at least 3 watts.


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## Oogabooga (May 20, 2016)

In my experience, do not get epoxy directly on your LED - it will seriously mess it up and cause premature failure.


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## flatfish (Jun 15, 2016)

RJN, have you found the chip we both seem to be looking for??
I cannot seem to find the answer either.


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## 8bit_brain (May 10, 2017)

RJN said:


> Hi everyone, new member here. I'm looking to build a flounder gigging light similar to one I bought. My only question is regarding how to waterproof the COB chip itself (e.g. silicone, epoxy, etc.) so that it can be submerged in saltwater. Any suggested products would be greatly appreciated. The light I have is mounted to an aluminum heatsink embedded in clear silicone or epoxy. The material isn't rock hard but almost feels rubbery. Thank you for any help.
> 
> Also, do you have to have a subscription to post a picture saved from your computer?


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## 8bit_brain (May 10, 2017)

RJN said:


> Hi everyone, new member here. I'm looking to build a flounder gigging light similar to one I bought. My only question is regarding how to waterproof the COB chip itself (e.g. silicone, epoxy, etc.) so that it can be submerged in saltwater. Any suggested products would be greatly appreciated. The light I have is mounted to an aluminum heatsink embedded in clear silicone or epoxy. The material isn't rock hard but almost feels rubbery. Thank you for any help.
> 
> Also, do you have to have a subscription to post a picture saved from your computer?



ANY NEWS ABOUT THIS?


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## lucca brassi (May 11, 2017)

What is problem ? Made holes on alu box corners , make threads , then put some silicone over aluminum box edges and screw down Plexiglas cover with holes. It is not rocket science :candle:


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## poolman966554 (May 16, 2017)

Has anyone tried Corrosion X on leds?? ive recently built up a racing drone, as its a new hobby.. Came across this after my first Flight controller died after a crash in long wet grass.


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## ssanasisredna (May 17, 2017)

poolman966554 said:


> Has anyone tried Corrosion X on leds?? ive recently built up a racing drone, as its a new hobby.. Came across this after my first Flight controller died after a crash in long wet grass.



Great stuff but not for extended immersion and though it may not do damage, it could damage the silicone lens. Best to use a cover plate and a silicone seal. If you have access to "dry air" ... and I have even done it with cold spray, you should try to evacuate the moist air. I hear assembly in the bottom of a chest freezer can also work .... don't mix the air up too much. The cold dry air falls to the bottom and prevents moisture inside.


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## mnm99 (Nov 12, 2017)

I know it's an old thread, but I had to respond. I use MG Optical clear encapsulating epoxy. I've used it on many under water lights. I made many without any problems. You do need special tools like a vac pump and an oven to bake them. https://www.mgchemicals.com/product...-potting-compounds/8322-optically-clear-epoxy I would post some pictures of my lights, but the form won't let me??


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## DIWdiver (Nov 12, 2017)

You have to host the pics on another site and insert the URL in the "Insert Image" dialog box. If you use dropbox (like me) you have to edit the URL they give you a bit.


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## ssanasisredna (Nov 13, 2017)

ooops


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## ssanasisredna (Nov 13, 2017)

mnm99 said:


> I know it's an old thread, but I had to respond. I use MG Optical clear encapsulating epoxy. I've used it on many under water lights. I made many without any problems. You do need special tools like a vac pump and an oven to bake them. https://www.mgchemicals.com/product...-potting-compounds/8322-optically-clear-epoxy I would post some pictures of my lights, but the form won't let me??



For the short amount of time you are likely using them and/or not high temperature differentials it is probably fine. However, it is not a recommended material as it is hard and tends to yellow as the heats the front of the phosphor on an LED can achieve. Under water, that temperature is likely not an issue, but thermal stress on bonds could be. Again, being underwater, that may be reduced.


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