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  #1  
Old 02-05-2013, 10:52 AM
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Dean_aeroleds Dean_aeroleds is offline
 
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Default HID vs. LED

A customer inquired about the comparison between HID landing lights and our Sunspot 36 for a certified installation, and I provided the following technical information that I thought folks on VAF might be interested in seeing:

Here are the Pros and Cons:

Power Consumption: 35W HID = 40W with ballast, Sunspot 36 = 45W
Initial Lumens: 35W HID claim 3200 lumens, Sunspot 36 1500+ lumens
Lumen maintenance: HID is 70% in 3000 hours LED is 95% @ 10,000 hours, 70% at 50,000 hours
External Ballast: HID: Yes, ballast must be mounted Sunspot 36:No, drop in bulb replacement
Built-in Pulse: HID: No; external controller Required LED: Yes
Power Cycling Wearout: HID: Power cycles erode electrodes LED: not affected by power cycles

Here are the lumen maintenance curves for various light sources:



HIDís follow the Metal Halide curve in the above graph. Our LEDs follow the High Power LED curve.

The thing that is not shown is the affect of power cycling on life, as these are constant operation test curves. Incandescent, Metal Halide, High Pressure Sodium (HPS) and fluorescent lights all have their lives shortened by power cycling, while LEDs are not affected by power cycles. The primary wear mechanism in fluorescent and arc lamps like HIDs and HPS is ion bombardment of the cathodes that erodes metal. The erosion of metal does two things, it coats the inside of the glass with a thin film of metal that reduces light output over time, and it increases the re-strike voltage needed to get the arc started and to maintain the arc. Eventually the bulbs become difficult to start and will begin to go out after operating for just a short period. This is commonly seen with street lights that start to cycle on and off. The show Mythbusters did a show where they tested a bunch of light sources for life and reliability, and found that as soon as they started doing power cycling, all of the bulbs they tested died except for the LED bulb. http://www.youtube.com/watch?v=qgM0N7GD5Ic The most interesting result comes toward the end of the video (starting at 5 minutes into the video).

We had one operator we spoke with that used his HID a lot report that the bulbs only last about 1 year before they need to be replaced due to power cycle wearout. The lights start to turn off shortly after they are turned on due to the increased arc voltage required by the increased cathode/anode gap. The ballast canít maintain the arc once the voltage exceeds what the coil can generate. The light output at this point is also greatly diminished.

So, to summarize, and HID can be a very good light, but it will require periodic bulb replacements depending on the usage duration and power cycle count, and you need to mount the ballast someplace. LEDs are simpler to install and are maintenance free as they will outlive most airframes.
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  #2  
Old 02-05-2013, 02:55 PM
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JonJay JonJay is offline
 
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Hello Dean -
I mean no disrespect, but that graph is grossly over generalized and outdated. Typical of what I see from the internet peddlers (the people who put the graph out, not you).
As an example, cathode errosion in HID has been dramatically improved with the introduction of ceramic arc tubes and pulse start technology and many Flourescent lamps are now exceeding 50,000 hours of life. The current "high technology" headlight in the automotive industry is not LED, not HID, it is in fact, Halogen. While I can not speak for them, we are seeing life above 10,000 hours for Halogen in commercial MR16 packages. Who would have figured?

To add a few points, life of an LED, the actual LED die, the part that makes the light, means nothing. It is a chip on a board. The life of the system is what is important.
In the commercial world, LED's are tested to standards for lumen depreciation. It takes months and even years to be able to accelerate the testing to be able to claim you meet them. So, manufacturers can claim whatever they want, but if they don't meet the standards, they are not approved by the DOE, Utility companies, or the professional lighting design community.

Raw lumens are also unimportant, what is important is how the lumens get delivered to the task. Hence, there is no merit in stating lumen output for an LED fixture. Delivered lumens is what is important. Once you take an LED lamp and put it into an enclosure, like a wing tip, it is no longer a lamp, it is a fixture.

The good news here for LED's is the lumens can be delivered to the task more efficiently than with other sources for many applications. However, why is that necessarily important in an airplane for an application that has such a low percentage of time in use?

The life of LED systems, lumens per watt, color, etc... are all improving rapidly. I think there will be a time soon that LED's for headlight applications will start to come into their own. But for now, the choice is high performance quartz with sophisticated reflectors. At least for the auto industry.

I think your product has merit. But I also think you should stick to performance comparisons of your product to the specific HID and quartz products currently in use. Test your product to a standard and publish it. Then nobody can question what is best for the application.

So with all that dribble;
What standards are you testing to?
How many years have you been testing them to proof?
What warranty are you putting on the product? (Standard commercial warranty for LED fixtures and systems is currently five years, ten for some, and moving toward ten as a standard.)

I am not trying to pick on you. But when you start off a post with a graph like this one, I just have to jump in.
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  #3  
Old 02-05-2013, 06:31 PM
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Dean_aeroleds Dean_aeroleds is offline
 
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JonJay,

Our warranty is 5 years.

We test to RTCA DO-160, which is the environmental standard for aircraft components.

The LED is the only real life limited device in our product. The other parts are either passives or high reliability semiconductor devices with no real wear out mechanism. Our MTBF is very high when the MTTF of each component used is considered.

The LEDs we are using have actual real time (not accelerated) life test data out beyond 10,000 hours at 80C by the manufacturer with 95% lumen maintenance at 10,000 hours.

Our lumen numbers are measured, not calculated.

I have seen multiple sources that show typical 70% lumen maintenance of HIDs at around 3000 hours, not just this particular graph. The LED curve shown on this graph matches well with most of the IES LM-80 data from the major LED manufacturers, so I'm not sure what your beef is with this graph, it looked reasonable to me.

HIDs are good lights, and I am not trying to disparage them, but they do have shorter lifespans than LEDs. That is all I was trying to show with the graph.

Best Regards,

Dean Wilkinson
CTO, AeroLEDs LLC
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  #4  
Old 02-05-2013, 07:06 PM
jetdriven jetdriven is offline
 
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How does your LED lamp compare to our XeVision 50W HID? It is advertised at 750,000 candlepower and a 2,000 hour life.
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  #5  
Old 02-05-2013, 07:50 PM
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Dean_aeroleds Dean_aeroleds is offline
 
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Hi Byron,

A 50W HID will produce about 4500 total lumens.

Candela = Lumens / steradian, where steradian is the solid angle of the beam

To hit 750,000 candela, that light has to put about 2000 lumens into the central 2 degree arc of the beam. That means the light is very tightly focused.

Our Sunspot 46 (PAR46 size LED) produces over 4000 total lumens (close to the 50W HID), but it delivers a wider beam width (10 degree beam arc). As a result, the peak candela is just over 120,000 but it lights up a wider field of view.

High candela numbers are impressive sounding, but they don't tell the whole story for visibility of a given light. HIDs are available with various reflectors, and using the tightest beam reflector will give the longest distance and highest candela value, but also the narrowest field of view. On short final and flare, this can make it harder to judge your flare or to see the edges of the runway. Many HID users opt for the wider optics and lower peak candela values to get a more balanced light (distance vs. field of view).

I have a green laser pointer that puts out over 1,000,000 candela peak, but it is so narrow that it doesn't provide any useful illumination as an example of candela taken to the extreme. The number sounds impressive, but its not very useful as a flashlight.

Hope that helps,

Dean Wilkinson
CTO, AeroLEDs LLC
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  #6  
Old 02-05-2013, 10:28 PM
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Dean, if the chart accurately represents the other choices a builder has, my apologies. It does not accurately represent commercial lighting, as it is so titled, or it represents the very worst of available technology with exception of the LED. That's my beef with the graph.
Are the products available to builders in HID that dated? The rest of it does not apply or matter.
Thanks for answering the other questions. A five year warranty is very good.
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  #7  
Old 02-06-2013, 06:05 AM
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Am I reading it right? The sunspot uses 5 more watts than the HID and puts out half the lumens? How many $12 HID bulbs can one replace before the total cost reaches that of the $450 sunspot? I'm sure it's as much marketing as your graph, but the duckwork hid's claim lifetime bulbs.

The LED industry pushes very hard in my field as well, with lots of charts like the one shown here. They make huge claims and equally huge price tags, and we still have to replace them when they fail. If a sunspot fails at 6 years old...what is the cost to replace?

One other thing. Your website says 1000 lumens for the sunspot 36 here but you're quoting 50% higher than that in this post. Am I reading something wrong?
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Last edited by ColoRv : 02-06-2013 at 07:50 AM.
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  #8  
Old 02-06-2013, 08:25 AM
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Bill - just to be clear, I am not picking on LED technology or Dean's product.
Lumens per watt of the source is only part of the picture. Putting the light where you need it is where LED's can and do outperform traditional sources in many applications. While I do not think it makes sense as a landing light, today, performance is increasing almost daily and costs are going down almost as fast.
I am a huge fan of LED technology. In 2011 5% of our commercial business was LED. Last year 15%. We are currently stocking distributor shelves and since the first of the year 25% of that stock mix is LED. I expect by 2015 50% of all that we sell will be LED. There are many solid products out there.

If you think about this impact, there has not been a new source developed (outside of induction technology, a whole nother can of worms), in 50 years. Now we have a technology come along that in a few short years will replace 50% of what we knew. That is huge!
So, don't throw out the idea. LED's are big business and they are here to stay.
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  #9  
Old 02-06-2013, 10:20 AM
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Dean_aeroleds Dean_aeroleds is offline
 
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Hi JonJay,

All the sources I can find on the subject of automotive HID bulb life states that they have a rated life of 2000 hours. Rated life most likely includes both lumen depreciation and wear out (arc voltage). I used that graph because the two curves I was most interested in appear to accurately represented the data I have seen for both technologies (HID and LED). The other curves may or may not be accurate, but I was not interested in them for my discussion. You may be correct on the other curves, but I wasn't really looking at them.

Dean

Quote:
Originally Posted by JonJay View Post
Dean, if the chart accurately represents the other choices a builder has, my apologies. It does not accurately represent commercial lighting, as it is so titled, or it represents the very worst of available technology with exception of the LED. That's my beef with the graph.
Are the products available to builders in HID that dated? The rest of it does not apply or matter.
Thanks for answering the other questions. A five year warranty is very good.
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  #10  
Old 02-06-2013, 10:23 AM
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Dean_aeroleds Dean_aeroleds is offline
 
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Hi JonJay,

Stop by our booth at Sun N Fun or Oshkosh this year and check out our LED landing lights. You may be surprised at how bright they are...

Dean

Quote:
Originally Posted by JonJay View Post
Bill - just to be clear, I am not picking on LED technology or Dean's product.
Lumens per watt of the source is only part of the picture. Putting the light where you need it is where LED's can and do outperform traditional sources in many applications. While I do not think it makes sense as a landing light, today, performance is increasing almost daily and costs are going down almost as fast.
I am a huge fan of LED technology. In 2011 5% of our commercial business was LED. Last year 15%. We are currently stocking distributor shelves and since the first of the year 25% of that stock mix is LED. I expect by 2015 50% of all that we sell will be LED. There are many solid products out there.

If you think about this impact, there has not been a new source developed (outside of induction technology, a whole nother can of worms), in 50 years. Now we have a technology come along that in a few short years will replace 50% of what we knew. That is huge!
So, don't throw out the idea. LED's are big business and they are here to stay.
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