LED project

wreckmaniac

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I'm building a new light. My old one is HID but I want to build one using LEDs. I have 9000mcd 30deg. ultra bright white LEDs. How many of these do you think I will need in the array to achieve close to the equivalent of 1100 lumens or so?

If I did the conversion right, each one puts out around 113 lumens. Can I just have an array of 10 and get 1130 lumens? Also, I have read that you don't need reflectors when using LEDs.

Thanks,
Dale
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<font color="gray">Most divers don't realize their limitations, and when they do, they're about to die.</font>
 

evan9162

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Nope

Each 5mm LED (like the kind you have) puts out 2-3 lumens. Thus, you're going to need 400-500 LEDs to equal the 1100 lumens that your HID systems outputs. Also, you are going to get a very wide angle (40 degrees or so), and thus, it will be a very wide flood rather than a spot like your HID system would output.

Finally, your HID system likely used 10-20 watts, while an equivalent LED system would require 40-50 watts to output the same light.
 

wreckmaniac

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Are there any "high output" LEDs that would be a reasonable alternative to my HID system? This is used in deep wreck diving where it is pitch black at times. My HID is 18 watts and puts out 1150 lumens. The light head is about the same size as an MR-16 and I would like to keep it along the same line as that.

Thanks,
Dale
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<font color="gray">Most divers don't realize their limitations, and when they do, they're about to die.</font>
 

Haesslich

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None that I could recommend at this time, I'm afraid - there aren't any LEDs that are high enough output yet for this sort of task, and most of them would take the above-noted 40-50 watts to do the same work your 18 watt light does. The only thing that comes close that I know is publically available is the Luxeon 5-watt, and you'd have to have 10 of those at max output to get 1200 lumens. That's 50 wats of power there, with a sharp drop in the distance the light will travel as well. Given their design, focus is also going to be an issue for you, so I'd stick with the standard HIDs.
 

wreckmaniac

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Okay...how about LED vs. MR-16 Halogen?

Dale
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<font color="gray">The liver is evil and it must be punished.</font>
 

idleprocess

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It sounds like you ought stay with your HID system - 1100 Lumens @ 18W is around 64 Lm/W - substantially better than any production white LED can do.

I have an extensive database of white LED specs and rudimentary calculations if you want to do some research.

Better high-power LEDs average 20-25 lumens per watt. Low-power 3/5/8/10mm thru-hole LEDs can do a bit better, but at the expense of "lumen density."

Your "superbright" 5mm LED is probably rated to 20mA x 3.5V, which comes up to 70mW. I'm calculating 9k mcd x 30 degrees at around 1.93 lumens, for a decent efficiency of 27.1 lumens/watt. Pack around 600 of those together and you can get >1150 lumens. Of course you'll need to supply 42 watts to the array, and 5mm LEDs can't manage heat at all.

The Luxeon V portable is the most powerful single LED on the market today. They commonly put out around 20 Lm/W, but can theoretically go as high as 40 Lm/W (the famed and rare X-bin). Bear in mind that the design lifespan for this emitter is 500 hours. Assuming you get lucky with W-bin emitters, putting out 148 Lm @ 5W, you'll need 8 for 40 watts. Expect to pay around $40 per Luxeon 5W emitter.
$320

You could do better cost-wise and be looking at around 20,000 hours of design life with the Luxeon III 3W emitter, which can be driven at close to 4W. A somewhat-premium T-bin emitter can do 84 Lumens, for 21.54 Lm/W. You'll need around 14 emitters & 55 watts of power. Expect to pick up LuxeonIIIs for around $15 each.
$225

You could experiment with the Lamina Ceramics BL-3000 integrated array - a pair of those might get you close to 1300 lumens... but their efficiency isn't as good as the Luxeon - 23 Lm/W, so plan on 49 watts to a pair and make sure you heatsink the bejeebers out of them. Expect to pay somewhat over $150 per BL-3000 array, if you can find them.
>$300

I don't see any engineering economy for LEDs in this application. I'm sure that HID bulbs & ballasts are costly, so perhaps it coulld be justified on a long-term cost of ownership basis.

If you can't meet the above criteria, you could just do it for the heck of it /ubbthreads/images/graemlins/evilgrin07.gif
 
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