Perfect!
No, don't make the heat sink from the zinc as it will be eaten away over time saving the aluminum. Just bolt a little piece to the aluminum.
Yes water is a wonderful thing. We have built a couple of 1500 watt power supply load boxes with the transistors soldered to 8 inches of copper water pipe with a little water flowing thru it. Stays pretty cool.
Could you post your link to the driver?
Maybe a sketch of the whole thing?

 

Zinc attached as a sacrificial anode, preserving the aluminum.

I ordered the new enclosures form polycase, so I am excited to get started on a better design. I hope the cooling is sufficient so the high heat produced doesn't cause the aluminum to flex or move too much. With direct contact with water, I think it will perform much better!

So, the buckpuck won't work according to David at LED driver. c o m. with 8 strings of 3, It will need a driver with output current of 5,600 ma to deliver 700 ma to each LED. The most powerful driver they have is a buckblock which only has an output current of 2100 ma.

I'll look on lux drive and see if I can find something. I may have to build something from scratch. I'm not overly concerned about the steady current delivered to the LED's with the engine running, or off. However I do want protection from transient spikes, surges in the system from running other pumps or devices.

 

Be careful running them without anything to limit the current. That may be part of the problem that made them run so hot. Don't be afraid to run them at say 500 ma, they will last forever there but not so much over the spec. Don't wire them up until we find a driver. It may be easier to hook 8 in series and drive them with 2.1 amps at 29 volts.

 

I had to order new enclosures, so while I'm waiting will be a good time to find a driver.

I found this one that looks good. It's a switcher and should have good efficiency.

http://www.ebay.com/itm/DC-8A-80W-A...597?pt=LH_DefaultDomain_0&hash=item5402fda2dd

 

So the only one I can find that looks like it would do it is the one I posted earlier. It would run 3 sets of 8 in series.
OR the cheap and dirty method would use 2 of these in parallel with each other then in series with one of the led wires. You could mount them under the dash. the down side of this method is that with the engine running and the battery at 14.5 volts or so they would be real bright. Probably about 700 ma by the time you add a little resistance for the wires. And with the engine off probably around 500 ma or so. This is the same principal as the one with 25 feet of wire, but a little cleaner.

http://www.mouser.com/ds/2/427/cp-205274.pdf

You could then clamp the voltage with a 1N6277A / 1.5KE18 like this:

http://gt.mouser.com/Semiconductors...des/_/N-azknd?No=25&P=1yzv44xZ1z0x8f2Z1z0x7uo

This is probably the best solution that doesn't cost a fortune.
If you like the idea I'll draw a picture.

 

Ronv , so I think it would be best for my application and put a single driver per light.

The driver you listed earlier looks good, and if I can solder an external pot, since the internal pot has a short mechanical lifespan. http://www.ebay.com/itm/5-30V-to-0-...054?pt=LH_DefaultDomain_2&hash=item3f2d0d9b26

Am I reading it correctly, it only has an output of 30 watts? Or was that the rating of draw on the driver itself?

Just to recap, each light will have: 24 x's 3 watt LED's. (72 watts total) FOUR LIGHTS on the boat 288 watts total.

The final installation so I can set the current threshold, and VDC threshold on the driver itself, and then use the external pot to dial it up and down, thus the dimming effect? I would like to have two switches on the dash of the boat, and two dimmer pots below each switch. Each switch will operate 2 lights. The finished product will have one GREEN switch X's 2 GREEN LEDS (72 watts x's 2 lights 144 watts total) and a second switch to operate the two blue LED lights. Dimmer pots below.

PM me your email address so I can paypal you.

 

Also, since the LED's will be drawing 5.3 amps. Wouldn't that be at the peak threshold of the one above? It only goes to 5 amps. Would it be better to get this one, since it can go t 8 amps. I can set it at 5 and it wouldn't be working too hard to maintain, at it's peak current?

http://www.ebay.com/itm/DC-8A-80W-A...597?pt=LH_DefaultDomain_0&hash=item5402fda2dd

 

Sorry, the posts must have passed in the night.
The trouble with the plain buck converter is that the input needs to be a few volts higher than the output. (not real clear in the spec.)
But, If we change the configuration a little bit we can use a boost only like this:
http://www.ebay.com/itm/DC-to-DC-10...005&prg=9373&rk=2&rkt=6&sd=141218167805&rt=nc
Much better price than the $50 buck boost.
Here is what I would suggest:
Put 8 in series then 3 of these in parallel.
Run them at .6 amps.
Voltage drop for each LED = 3.4 to 3.8, so we might need as high as 30.4 volts max. but only 1.8 amps max. About 55 watts.
Do you have a volt meter with a 5 or 10 amp scale?
We will need to remove one of the little potentiometers and replace it with a big one and maybe a small fixed resistor so the current can't be set to high.

 

Ha, probably so.

The way I read this one, and looking at the capacitors on board, I am guessing it stores a little bit of a charge and delivers a steady output of current/VDC. I have 4 batteries on board. I could always run two and pull 24 volts to the driver. It's well with in the range needed to provide a stead y 12 vdc.

http://www.ebay.com/itm/DC-8A-80W-A...597?pt=LH_DefaultDomain_0&hash=item5402fda2dd

That 150 watt buck boost is a monster! Check out those heat sinks! That's a pretty powerful little converter. Very interesting. At that price, I may pick up one of those too, runs some tests and measure.

Yes, my volt meter does. So you thinking de-solder the existing pot and add an external pot for dimming capability right? Do you have a favorite style pot you prefer. Keeping in mind it has to mount on a less than 1 mm thick panel. I'll add a knob, for turning.

 

The way I read this one, and looking at the capacitors on board, I am guessing it stores a little bit of a charge and delivers a steady output of current/VDC.

Yes, both current and voltage are adjustable.

I have 4 batteries on board. I could always run two and pull 24 volts to the driver. It's well with in the range needed to provide a stead y 12 vdc.

Are your batteries in series??? Usually they are in parallel and charged with a single 12 volt alternator.

http://www.ebay.com/itm/DC-8A-80W-A...597?pt=LH_DefaultDomain_0&hash=item5402fda2dd

It looks like it would work on 24 volts in.

Yes, my volt meter does. So you thinking de-solder the existing pot and add an external pot for dimming capability right? Do you have a favorite style pot you prefer. Keeping in mind it has to mount on a less than 1 mm thick panel. I'll add a knob, for turning.

Yes, although I can't read the value from the picture, so we would need to wait for them to order the adjustment pot.

 

I have two batteries wired in series to operate my 24 volt trolling motor. The other two batteries have a switch to toggle between battery #1 or battery #2...or I can set the battery switch to ALL, to charge both batteries from the engine alternator.

I was going to set up a wire terminal block to make all my driver/light connections. Fuse protected, and from there I can wire to the batteries in a 12v or 24v configuration.

The one driver you linked to the 5 amp would be ideal. The 8 amp I linked can handle more of a load, but would have to add a metal oxide wirewound resistor to limit current like you suggested.

I will try and find a suitable pot, 1k to 10k I believe would be sufficient to get the dimming affect.

Which values were you looking for in the image, the micro fared rating on the capacitors?

 

The 80 watt one you linked is a good one. It has an adjustment for current and one for voltage. They are the little 10 turn pots at the top right hand corner of the picture. We want constant current so what we will do is set the voltage somewhere say 5 volts then use your meter on amps across the output - yes a short. We can then adjust the current to about 5 amps. We will need two or three measurements of the current and the resistance value of the potentiometer (with power off) so we can pick the right value for the big one. After that you just need to set the voltage to say 13 volts ( it needs to be higher than the drop of 3 leds) and the supply will keep the current at 5 amps. So this is more complicated than a buck puck because we have to replace the pot,

 

Sounds good, I don't mind getting into it a little more, with having to remove the pot. It's worth it for the end result.

They're on order, China. Every time I order parts I sometimes get them in a week, other times a month. Hit or miss, but the package was already shipped so hopefully soon.

Curious, have you ever used RGB LEDs? A controller/driver for them to rotate through the color spectrum. I've used them on LED strip lighting and tubes. Pleased with the results. I was considering duplicating this same project, with RGB LED beads.

http://www.ebay.com/itm/50pcs-3W-Hig...item51bb830b2b

Just looking at the variables on specs. The only major variance is in the RED LED with a drop in VDC handling, Curious what your thoughts are with these. All in one driver, that sort of thing.

Parameter​

Value​

Lens​

Water Clear​

Emitted Color​

Red, Green, Blue​

Viewing Angle​

120°​

Forward Current​

300mA​

Forward Voltage​

Red​

2V to 2.5V​

Green​

3.2V to 3.6V​

Blue​

3.2V to 3.8V​

Wave Length​

Red​

620 to 623nm​

Green​

520 to 523nm​

Blue​

460 to 465nm​

Intensity Typical​

Red​

30 to .5 Lm​

Green​

40 to 45 Lm​

Blue​

15 to 20Lm​

 

Ronv, I wanted to get your input/advice on the LED mounting. I am trying to make as close a contact to my aluminum mounting plate as possible when seating the LEDs. What do you use for your mounting preference; thermal grease, thermal adhesive paste, thermal pads?

I've noticed when using the thermal adhesive paste, the contacts on the LEDs are making contact with the aluminum. This is a problem as it arcs the connection. I test continuity on each contact and the aluminum, finding an LED contact making connection with the aluminum, I lift the LED slightly off the plate so it doesn't make contact. I can lift the tab on the outside connections on each strand, but the inside connections not so much.

I was thinking the thermal pad would be better to allow thermal conductivity to the aluminum/water while insulating the LED contact connection, frying the LED. And less messy!

Artic silver is good too, but I would still have the same issue.

 

Those LEDs are supposed to be mounted to a PCB which has pads for the electrical connections on each side, and then a large copper pour area to act as a heat sink. In your situation, you could instead use vias (through-plated holes) from the top to bottom layer to conduct the heat from the base of the LED to either the water, or to the heat sink. Either way, you will need to have the heat sink or the bottom side of the board in contact with the water, as the plastic of the box won't likely conduct heat anywhere near well enough to keep the LEDs from melting.

Here is an example of a PCB layout for just 15 of those LEDs; if each LED had a Vf of 3.6v, the total Vf would be around 18v:

Vias to the bottom are not shown; neither is shown a "copper pour" area for the top and bottom sides. I rotated the pads a bit so that the routes between them would be as direct as possible. The dotted red line is the outline for a polygon (copper pour) area that was left unfilled. The .sch and .brd files are viewable/editable using the freeware version of Cadsoft Eagle v6.4

The Vf of LEDs decreases with an increase of temperature, which is why they have to be supplied by a current source rather than a voltage source, or they can wind up in a "thermal runaway" situation where they wind up melting down.

 

Oh #$%*, totally forgot the little heatsink tab in the center is hot. They make boards for this. Let me see what I can find.

 

The metal clad boards for those bridgelux leds are ALL over EBAY..

I still recommend using 1 single 100W "multichip" LED.. It comes pre mounted to an aluminum insulated backer plate that can easily be mounted to a heatsink with the holes in it.
Then a constant current boost driver and voila... clean/elegant..

like this
http://www.ebay.com/itm/100W-100-Wa...580?pt=LH_DefaultDomain_0&hash=item1e7ba18bfc

 

I ran tests on thermal heat produced, based on ronv's design, aluminum plate in direct contact with the water, by opening up the enclosure. Temp on the plate using temp probe on my meter was around 80-85F on the backside of the LEDs. on the front side of the LEDs around 78-79F. While fully submerged. The true test would be after I run them for 3 hours and then turn them off to trailer the boat out of the water, giving them enough time to cool when they come out of the water and not overheat before cool down in the ambient air.

I looked for a PCB layout that would work for my enclosure. No success, unless I make one from scratch. I used non-conductive strips to place between the LED leads and the aluminum, so no contact is made.

Mcgyvr, I like those chips. I wonder how many lumens they emit? Can they handle the abusive marine environment? Shock impact, dynamic pressure, etc.

I'm also updating my power supply for testing. Adjustable current/VDC for my 12 volt projects. Any favorites you all prefer?

http://www.ebay.com/itm/30V-10AMP-1...848?pt=LH_DefaultDomain_0&hash=item1c36e761f8

 

I'm thinking of designing a float switch, so the light cannot run out of water. Sort of a starter circuit interrupt, unless the boat is in the water.

 

Mcgyvr, I like those chips. I wonder how many lumens they emit? Can they handle the abusive marine environment? Shock impact, dynamic pressure, etc.

I'd consider them more capable of handling it than your current method. Just far less "pieces" to worry about.. bolt it on and go.. they have lenses,etc.. out there too for them.. It would be super simple to pot the whole thing and be done..
I think its like 6K lumens for the green and you can get close to 10k lumens with other "white" colors.
but here.. this diving flashlight should say something about their usage in the water..
http://www.ebay.com/itm/Archon-D100...2535447?pt=US_Flashlights&hash=item3cdf308017


maybe some waterproof lens similar to these http://www.ebay.com/itm/66mm-LED-Le...242?pt=LH_DefaultDomain_0&hash=item27d81ce69a
maybe just a simple metallic can.. mount the led on it.. bolt on the waterproof lens and voila.. similar the diving light..