So a project I have this week is to install 10 of these 200w LED floods, each fixture contains four 50w on-board type chips (pic below). What I find very hard to understand is how can all that heat be dissipated? These fixtures come with a 2 year warranty by the manufacturer. There is no active air cooling by fans, just some short fins on the back of the unit, the whole thing is passively cooled. They claim an equivalency to 1000w metal halide, but im very skeptical. These are going up on a golf course driving range that currently uses 6x 1000w MH and 6x 400w MH. What do you guys think? any guesses when they'll begin to fail?

First: Are the LEDs themselves heatsinked? What about the driver?
Second: what are the szes of the heatsinkes (depending on the answer to #1)
Third: what is the voltage?

@Solanaceae: The heatsink is the complete (aluminum?) body of the lantern, so once the LED modules are mounted on it properly, it could keep the temperature reasonable. Provided it is physically large enough.

How big is that?
When calculated 600x200mm, ambient temperature of 30degC and still air and 30W radiated as light, it end up with about 70..80degC on the surface, so about 100degC on the chops (I mean really the semiconductor), that is still manageable for ~20khour.

However the claim of "Replaces 1000W MH" is ridiculous, even with an HID efficacy of 50lm/W and LED efficacy 100lm/W (and no ballast losses) the "equivalent" would be just 400W.

Given the more realistic figures (60lm/W for the MH and 75lm/W for the LED's operating at the 100degC), the equivalent to count on would be about the 250W.

The LEDs are simply attached to the inside back of the fixture housing, which acts as the heatsink. The housing has fins about 3/4" in height, spaced about 1/2" apart. That's it. The fixtures are surprisingly lightweight, so the metal housing must be quite thin.

According to the data sheet on these, the LEDs are "Epistar 50w LED module 4200K", and the fixture is "IP66" rated. Operates on 85v to 240v (I will be connecting them to the existing 240v supplying the current MH lights)

@medved I agree, that equivalency rating is complete bogus. I haven't actually tested one of these yet, but I already told the golf course owner that he'll likely be in for quite a brightness loss disappointment compared to the existing MH lights, even considering some are near EOL. My first suggestion was that I relamp all the MH fixtures to restore intensity, but they already bought these LED floods, so it looks like ill be installing them.

The heatsink size depends on the power dissipation & the intended working temperature. If it is intended to work at high temperature it can do with less heatsink surface area - to some point, Medved have the math

Black painted heatsink also disipate larger part of the heat by radiation compared to natural Aluminum color heatsink

The driver of those things can be quite efficient, as long as it is separate from the LEDs, it can be in a box wihthout much heatsinking at all - at 200W and assume 90% efficiency (so 20W losses) without heatsinking it will run hot though, so may last only a few years before some electrolitic capacitor dries out

200W LED (assume ~100 Lm/W for top quality LED) is equal at best to a 250W quartz MH (~80 Lm/W) or 150W ceramic (~140 Lm/W). It is not uncommon for the LED manufacturers to lie here though

In the LED floodlights significant part of the light from the chip does not hit the reflector at all, so its light spread is more related to "from where you can see the chip directly" compared to HID where most of the light is controlled by the reflector. So the forward light is equal to even less Watts of MH

In the LED floodlights significant part of the light from the chip does not hit the reflector at all, so its light spread is more related to "from where you can see the chip directly" compared to HID where most of the light is controlled by the reflector. So the forward light is equal to even less Watts of MH

Also with good optics (full cutoff), light is related to "from where you can see the lamp directly", so subtracting reflection losses, you have to slighty increase power to get the same original luminous flux.
However, 1000W MH equivalency is ridicolous or can be truth if you consider an MH open luminarie, where only an fraction of light come to your measurement instrument.

The LEDs are simply attached to the inside back of the fixture housing, which acts as the heatsink.

That is actually the best you could do (as a lantern design engineer)

The housing has fins about 3/4" in height, spaced about 1/2" apart. That's it. The fixtures are surprisingly lightweight, so the metal housing must be quite thin.

The question is, what is the overall size of the fixture. I did my calculation assuming a 60cm width, 20cm height and negligible depth, just with about 2cm fins spaced about 30mm, whole body actiing as the heatsink.

Used this calculator.

Redone the calculation using following data:

Length = 80mm (represents height of the fixture; fixed in the Demo, so scaled down the power instead)
Height = 40mm (represents the fin height; fixed in the demo; because twice of your description, halved the number of fins)
Width = 200mm (= width of the fixture corresponding to 1 LED module)
Base thickness = 5mm (maybe overestimated; had 10mm before, not much difference; represents the thickness of the fixture body material)
Number of fins = 8 (Because the fin height is fixed in the calculator as twice your value, divided the number by two; otherwise correspond to number of fins belonging to 1 LED)
Fin thickness = 8mm (Expect about half of that, made wider, to have similar thermal resistance to your fin height)

Source length = 20mm (correspond to the 80mm height instead of the full 200mm)
Source width = 50mm (assume the LED modulke is about 50x50mm size)
Heat power = 22W (corresponds to 170W total, reduced to the calculated section of the heat sink; =170W*80mm/200mm/3)
Ambient temperature = 30degC (hot evening just after sunset)
Emissivity = 80% (assume black paint)
No external airflow (just the one caused by the heat alone; quite pessimistic, could be only when under some roof or so)

And get
Tj = 66.5degC (here the Tj means module base temperature, as the internal heat resistances were neglected)
Lower temperature than before, because before I count less and smaller fins...

That does not sound like something wrong, actually spot on, where the LED's are rated (by sound quality manufacturers)

But what matters is really the overall fixture size...



For the ballast: I don't think the conditions are worse than with many HID's, only the ballast is simpler, so could be more efficient (I would expect about 95%; here the higher efficiency makes it cheaper - less problems with heatsinking).

There is difference in the amount of light that hit the reflector, so get directed in the intended direction :



LED emit light into half sphere, and not equally : The flux coming in a certain direction is proportional to the area of the chip you see from this direction, so cos() of the angle from the center

In most FCO LED floodlights, the reflector is so shallow that none of this light hits it at all - all the light emitted goes directly to the front of the lantern without any reflector control

In better LED floodlights (like the one here), the reflector is flat in the plane which contains the chip (this plane does not do any usefull job), and parabolic section on the sides (that directs the light in the intended direction). But as the parabolic sections are at wide angle from the chip, only part (and not large part at that) of the light from the chip hits them



HID emit light into full sphere, equally in all directions normal to the arc, and cos() of the angle from the center in the planes that contain the arc

In FCO HID floodlights only about 1/6..1/4 of the light goes straight out (that is the solid angle of the pyramid with the arctube as its tip and FCO glass panel as its base, add or take the effect of loking at the arc from angle), so, 5/6..3/4 of the light hit the reflector and is directed by it. That is much better



Reflectance of Aluminum is >0.9 for all visible light spectrum. so i expect reflection losses from a polished Aluminum reflector (that stays clean in a sealed lantern) to be under 1/10th respectively

Interesting, I thought the cooling would be inadequate considering some of the other high power LED fixtures ive seen contain much larger heatsinks and some with fans on top of that. Medved, your dimensions are quite spot on. I took one apart today, (see pics below). The fixture wasn't actually grounded inside, the green (ground) wire was just cut and not connected to anything. The drivers are placed in the ends of the fixture (under the black portion of lens) two at each end. As you can see the drivers are just glued onto the housing, theres no screw mounts.

And there is only one ballast, or each LED module has it's own ballast?
Because I see the ballast unit is just 45W (the 50W is rather optimistic figure, assuming the LED voltage is closer to the upper limit, so practically only when cold; realistically I would expect something around 30V)

Before correction I was writing about "just 150W", but I was wrong: I have assumed 3 LED's, but there are actually 4 of them...

And other observation: The ballast is rated with maximum Tc=70degC, assuming ambient of 50degC (so deltaT about 20degC in free air). That means the ballast body would have to be well thermally coupled  to the heatsink, otherwise with the 60degC inside of the fixture it will overheat... It looks glued (likely by some heat conducting glue), but don't forget to do the same when replacing the ballast - when kept just free, it will severely overheat.

I find that gold thermal paste works well. I used it on my old computer last summer and it's been going stronger and cooler than with the factory paste.

https://www.youtube.com/watch?v=vbt2ojkXPuo

Seen this video before. The LED floodlight in the video, isn't different than LED floodlights in Israel, that marketed under the stickers "Eurolux", "Nisko", "Hyundai", etc...

@Medved, each LED has its own driver/ballast, there are four of them in each fixture. I will be installing these lights today, after testing I found they are much closer to a 400w MH, maybe even less light than that. After running for an hour or so, the back of the fixture gets VERY hot, to the point where you cannot touch it for more than a couple seconds. Kill-a-watt reads 207w for the entire fixture when first started cold, after an hour of operation that drops to 173w. Why is that?