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LEDs : Require urgent HELP about LEDs. Answered

Could somebody please answer me that using an array of 135pcs of 5mm LEDs that produce 12000mcd each be better than using 3pcs of Cree MC-E for a motorcycle headlight. will the 5mm LEDs produce more light (lumens) than the MC-Es. If yes then will the distance of the beam of light produced by the 5mm LEDs be the same as the distance of the beam produced by the Cree MC-E?  By the distance of the beam I mean how much far can the beam produced by an array of LED light up the road. Please answer somebody answer me quickly I need urgent help. I will be very greatful to youll

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R055_28Best Answer (author)2010-01-14

It is not very easy to compare mcd with lumens, so I would advise comparing the power dissipated by each option. Look at the manufacturers data sheet, if available, and find out how much power is dissipated by each bulb and then multiply by the amount of bulbs (remember the 5mm bulbs will probably be displayed in milli watts x10E-3). The one with the higher power rating will be the brightest. 
However, I would personally go with the CREE emitters because it saves having to connect 135 LED together and worrying about voltage and currents. I do think that you will get better range with them as well.
IMPORTANT - they go very bright but get EXTREMELY HOT, and you would need to bolt them to a heatsink to save them dying. 

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bhvm (author)2010-03-05

Vinet,
Stop wasting time with 5mm LEDs. They're complete junk, only suitable for Toys, Indicators etc. If you need some practical illumination, look at SEOUL p4 Z-LED which are now available in Bombay.  

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seandogue (author)2010-01-14

By using 135 units of a low output LED vs 3 high output devices, you've done two things aside from saving a couple of dollars.

1) Significantly increased your production cost

2) Significantly Increased the points of failure.

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steveastrouk (author)2010-01-14

Technically, you need to know the emission angle for the two source types. I would go with the Cree MC-E.

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jeff-o (author)2010-01-14

Use the CREE emitters.  I use a 3-emitter array on my bike and I can light up street signs from two blocks away.  The CREE emitters will also be easier to hook up and maintain.

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