DIY LED with dimmable drivers

[DaveS]

Looks great! Question for you and the three 10"x22" fixtures over a 6'x2'x2' bowfront. Is the 2' front to back at the apex of the bow or on the sides? I know you haven't put the optics on there yet but is there aqdequate lighting along the front and back edges? I got a 2' deep tank and just wondering if 10" would be enough depth on the fixture.

 

Would be very interested in seeing how that works once you do get the optics on.

 

Thanks!

[TonyD]

Looks great! Question for you and the three 10"x22" fixtures over a 6'x2'x2' bowfront. Is the 2' front to back at the apex of the bow or on the sides?

I will have to measure. It would make sense that it would be at the apex of the bow.

 

I know you haven't put the optics on there yet but is there aqdequate lighting along the front and back edges?

Yes. I have even spread of light. I was concerned with the spotlighting effect with LEDs but I have not seen that. It may happen with I put the optics on so we'll see. I move the middle LED kit forward from the 2 end LED kits to compensate for the bow.

[zygote2k]

some observations-

 

Why does the heat sink have to be so massive? how hot does the heatsink get? can you hold it in your hands without burning them?

If the heatsink runs cool, why the need for the fans? why not only 1 fan?

[TonyD]

I bought the 8.46" x 22" heatsink. Heatsink USA was out of stock with this size and Reefledlights upgraded me to 10" at no charge. I wanted a wide heatsink for a wider light dispersion from the back to the front. I thought maybe a 4" wide heatsink would have concentrated too much light along the center, and not enough towards the front and back. I probably could have gone with a 18-20" long heatsink and still have gotten the same light spread, but I figure 72" long tank so I needed to cover that length.

 

The heatsink does not get hot at all....warm, yes, but not hot. But I don't know if it's Winter and my house is cooler now. Who knows that it'll be in the summer months? I do plan on increasing the number of LEDs from 72 to 144 eventually so it's a bit of planning for future upgrades as well. 2 fans were for symmetry and a bit of overkill. Heat kills LEDs and at $6 per fan, it's a cheap investment to try and increase the lifespan of the LEDs compared to the initial cost of these kits. And with 144 LEDs in the long run, the heatsink may get hot enough that I would need 2 fans.

[zygote2k]

144? That seems like drastic overkill to me. I maintain a 90 that has 12) P38's and that seems like plenty of light. If you added another 50% for the 6' long tank, you'd only be at 90 individual leds. There are no fans on this set up and the P38's run warm to the touch with their very small heatsinks/cooling fins.

I have a 50w Cannon pendant that has an aluminum heatsink that is part of the structure of the light itself. There isn't a fan either. It is HOT to the touch, but not as hot as a halide. I've spoken with Ecoxotic and the manufacturer, EdisonOpto, about the heatsink temperature and both say that it cools sufficiently to guarantee the 50000 hr lifespan.

 

I've heard that the DIY'ers that use aluminum "U" channel have reported that it gets very hot, but how hot is detrimental to the lifespan of the actual emitter? If fans are used in conjuntion with heatsink, what is used to determine how much CFM is needed to cool a given amount of lights mounted on a particular style of finned heatsink?

 

Another idea for increasing the coverage of light while decreasing the actual physical size of the fixture would be to use a concave heatsink. The emitters could use wider optics in the center and tighter optics on the outer edges to adequately cover all of the area. You could even go so far as to make a series of stepped aluminum plates to aim the outer leds.

[DaveS]

. There are no fans on this set up and the P38's run warm to the touch with their very small heatsinks/cooling fins.

I have a 50w Cannon pendant that has an aluminum heatsink that is part of the structure of the light itself. There isn't a fan either. It is HOT to the touch, but not as hot as a halide. I've spoken with Ecoxotic and the manufacturer, EdisonOpto, about the heatsink temperature and both say that it cools sufficiently to guarantee the 50000 hr lifespan

 

I'm no expert on LED performance but I do know that the temperature of the heat sink when you touch it is NOT the same as the temperate at the actual LED. The latter is the one of interest as that determines LED performance/longevity. Aluminum is a pretty good heat conductor so there probably isn't a huge gradient between the two but comparing it to the temperature of a halide fixture probably isn't the right thing to do.

[TonyD]

144? That seems like drastic overkill to me. I maintain a 90 that has 12) P38's and that seems like plenty of light. If you added another 50% for the 6' long tank, you'd only be at 90 individual leds. There are no fans on this set up and the P38's run warm to the touch with their very small heatsinks/cooling fins.

I have a 50w Cannon pendant that has an aluminum heatsink that is part of the structure of the light itself. There isn't a fan either. It is HOT to the touch, but not as hot as a halide. I've spoken with Ecoxotic and the manufacturer, EdisonOpto, about the heatsink temperature and both say that it cools sufficiently to guarantee the 50000 hr lifespan.

 

I've heard that the DIY'ers that use aluminum "U" channel have reported that it gets very hot, but how hot is detrimental to the lifespan of the actual emitter? If fans are used in conjuntion with heatsink, what is used to determine how much CFM is needed to cool a given amount of lights mounted on a particular style of finned heatsink?

 

Another idea for increasing the coverage of light while decreasing the actual physical size of the fixture would be to use a concave heatsink. The emitters could use wider optics in the center and tighter optics on the outer edges to adequately cover all of the area. You could even go so far as to make a series of stepped aluminum plates to aim the outer leds.

 

144 LEDs may be overkill. If it is, I can always scrap it for parts on another LED build. Or I can use my dimming feature on the Meanwell drivers. And at $12 per LED kit for 2 computer fans, that's inexpensive risk mitigation to keep everything cool compared to the cost of the LED kit.

 

Using a curved heatsink is an interesting concept and I agree it would decrease the footprint, but any curved heatsink would be custom made and expensive (ie, not mass produced), unless you can bend it yourself. Of course, you could take sheet metal and bend it to a half-circle shape, then use fans the blow the heat away.

[BowieReefer84]

Tony,

 

The more I see your fixture the more impressed I am. Anyone needing assistance doing an LED project should contact Tony. I just had him wire up my dimming circuit. Very professional job using a small project box, heat wrap, and quick disconnects. Mine would have consisted of electrical tape and wire nuts...

 

I want to say having the ability to dim is almost a must for LED's. I made the mistake of going non-dimming first. You can really get a good color by dimming, and it really makes acclimating corals a breeze. No more having to start them in the sand, and move them up.

[TonyD]

You're welcome. Glad I could be of help.

[zygote2k]

I want to say having the ability to dim is almost a must for LED's. I made the mistake of going non-dimming first. You can really get a good color by dimming, and it really makes acclimating corals a breeze. No more having to start them in the sand, and move them up.

 

I have to say that I disagree with this statement. Dimming is a pure bells and whistles feature that is un-needed on ANY type of light system. As long as you're knowledgeable as to which corals can deal with varying light intensity and you don't overlight any given area, you'll be just fine without dimming.

After all, how many people dim their Vortech's? (rheostat=dimmer) Once you set them, you never touch it except in odd circumstances.

If you are able to get a controller to ramp up the LED's over a given time, like a true dawn to dusk effect, then dimming is necessary.

[BowieReefer84]

After all, how many people dim their Vortech's?

 

Lots... I bet very few run them wide open.

 

Dimming the lights is the same thing. Getting the color you want, just like getting the flow you want. It is personal preference, as well as finding the sweet spot for your tank.

 

I was basically saying thanks to Tony, not trying to start a debate. It is a very cool feature, and you may think of it as a "bell and whistle." However, it could also be viewed as a necessity. Not for the corals, but for your viewing pleasure. After all, the reason I have a tank is because I think they look cool.

[basser9]

Being able to dim atleast the white leds for color and par adjustments is something

you will want most of the time on any build.

Even if your leds are just warm to your touch the lower the temps the higher the par so the more you cool them the better.

Until you build a led setup with just c channell you will be surprised how hot they can get.

[zygote2k]

Being able to dim atleast the white leds for color and par adjustments is something

you will want most of the time on any build.

Even if your leds are just warm to your touch the lower the temps the higher the par so the more you cool them the better.

Until you build a led setup with just c channell you will be surprised how hot they can get.

 

You have this dimming feature on your halides or flo's? Does this dimming feature work automatically, or are you doing it manually?

 

If the manufacturer of an LED unit doesn't need a fan because there's an adequate heatsink, why make a fixture more complex by adding a fan to it? The Par 38's don't use fans- neither do the Edison Opto 50 and 100 watt "cannons", so they must not be needed. Does an LED work better at 130 degrees or at 85 degrees?

Anytime you run xx amount of electricity through a conductive metal, you're gonna build heat, but the real question is, "How much is too much?"

[chucelli]

The Par 38's don't use fans- neither do the Edison Opto 50 and 100 watt "cannons", so they must not be needed.

This statement is not accurate, as one of the main reasons for not using fans would be to cut down on manufacturing costs.

Does an LED work better at 130 degrees or at 85 degrees?

Anytime you run xx amount of electricity through a conductive metal, you're gonna build heat, but the real question is, "How much is too much?"

Lumen Maintenance

This spec sheet shows test results and projected lumen maintenance of Cree X-Lamps under conditions of varying ambient temperatures and its' effects on junction temperature. Employing active cooling (fans) will substantially increase range of "safe" operation.

Not using fans for units with densely packed LEDs doesn't mean they will burn out all the sudden. It just means that they will not maintain their rated output as long as an equivalent unit with a fan, especially in extremely hot environments.

-Robert