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From: Ken James (no email)
Date: Sun Apr 06 2008 - 21:56:23 EDT
Here is a brief explanation of why buying a 20$ LED light is not a good
way to get the most for your money, and why buying a light that is more
expensive "up front' can give you much more light per dollar.
http://www.hebeiltd.com.cn/?p=led.auto.piranha
http://www.luxeon.com/pdfs/DS56.pdf
I start by comparing the average LED used in cheap LED lights with a
state of the art LED not used in ANY cheap light.
In the top link we see the type of LED used in cheap LED lights as
compared to the state of the art models from such sources as Lumiled
(lower link)
The top LED puts out a beam pattern of 130 deg (warm white) and 7.4
lumens while using about 1/10th watt, the bottom LED puts out a beam
pattern of 140 degrees (warm white) and is now well over 200 lumens
(most efficient LED in the world, 3 X as efficient now as a fluorescent
bulb) while using about a watt of power.
This means that if I had lights of similar brightness, the one using the
top LED would use
*at least thirty LEDs for the same amount of brightness of the single
LED in the bottom link* ,
and the top link LED light would use
*over three times as much power for equal brightness* .
Pretty amazing, huh?
Not only that, but the more powerful LEDs are MUCH smaller than the
cheap models so that this combined with the number of LEDS needed for
the top link light means you would have to have many fixtures using
these cheaper LEDs to get as much light as ONE fixture using the more
powerful LEDs.
Add to that that most cheap LED 'drivers' in such lights are of the
'linear' type, and so waste 30-70 percent of the electrical power they
use, it becomes clear that spending more for better LEDs and LED
drivers makes very good economical sense.
For over a decade now, folks have been saying 'I'll wait until they
become cheaper" when thinking about LED lights.
Now they are cheaper, but folks still do not understand that buying the
cheapest 'up front' product they can get almost never gives you the best
deal for your dollar.
If you buy (or build) cheap you are wasting money, as well as electrical
power.-Ken
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