# multiple vs single led



## Axkiker (Aug 16, 2010)

So if you have read any of my prior threads im trying to figure out what is better.... one mammoth led or several smaller leds....

What pros and cons can you think of for each

I can say that the pros for a single led array are:

smaller housing
1 lens
1 reflector
easier to build

cons
I cant seem to find a dc to dc driver for a single. (may be the killer)


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## Th232 (Aug 16, 2010)

Other than what you've listed:

* For a given type of LED, multiple LEDs at a lower drive level are more efficient than a single driven at a higher level. Comparing different types of LEDs, I think XP-Gs are still the most efficient out there? If so, multiple XP-Gs in sufficient numbers will be your most efficient option in terms of total lumens/watts.
* Depending on the distance the LEDs are separated by, heatsinking could be easier for multiple LEDs.


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## LEDninja (Aug 17, 2010)

Housing size are determined by heat dissipation requirements, not the physical size of the LED. If you use a too small housing that cannot get rid of the heat produced, you just burn out the LED.


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## Essexman (Aug 17, 2010)

Make two lights, one of each type, compare them and let us know :twothumbs


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## Th232 (Aug 17, 2010)

LEDninja said:


> Housing size are determined by heat dissipation requirements, not the physical size of the LED. If you use a too small housing that cannot get rid of the heat produced, you just burn out the LED.



True, but I was under the impression that having to take away, say, 10W of heat each from six different locations was easier than taking away 60W from a single location without cooking the LED. The LEDs more closely approximate an isothermal source rather than a point source, therefore with a given heatsink, the highest temp (right under the LED or star) is lower for multiple LEDs compared with that of the single LED. Of course, if a heatsink was able to instantly (or close to) spread the heat over its entire volume, then they'd be equal.

Or is that distance too small to matter in the world of flashlights?


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## LEDninja (Aug 17, 2010)

I am referring to the size of the outside box/flashlight body. Total surface area to dump the heat to the surrounding air. There is a need to get the heat off the heatsink if runtime is needed for more than a couple of minutes.

It would be a lot easier for the heatsink to handle 4 sources of 2.5W each (4*XR-E) spread out over 4 quadrants than a single source of 10W (SSC-P7 or MC-E) either combination having 4*EZ1000 dies. But you still need to get the heat off the heatsink. The minimum total surface area of the outside box/flashlight body stays the same.


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## Th232 (Aug 17, 2010)

Very true, hence why I said heatsinking would be easier, not that less heatsinking would be needed. My first post didn't make any reference about heatsink size.

Edit: Or at this point in time are we on the same page but just reading from different lines?


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## MikeAusC (Aug 18, 2010)

What are you trying to light up - flood/spot ?

How much light do you need ?

How big can the package be ?

What batteries are possible ?


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