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Posted by Neo on February 21, 2010, 3:21 pm
 


I sort of figured it out on my own that your 15 LED strip lamp was
home-made and that you probably made it for bragging rights than
for money.  So who's your LED supplier?  Did you ever measure
the LED's lumen output at a fixed distance over time?  Did the
light output drop after it overheated - or have you figured out a
clever way to dissipate the heat so the light output is more stable?




Posted by ghio on February 21, 2010, 11:23 pm
 



Actually, the strip light is a commercial product.


I get them from the importer, TekSolar. And no, I don't retail them.
I get the lamps and put them into real use, reporting on their
performance under actual living conditions. If you are interested you
can probably purchase them from the CoilTek Gold Centre.


Never seen the point. It's not part of my reporting brief.


Heat has not been a problem with the striplights. In fact they barely
get warm. Tell you what, I'll measure the temp tonight and post the
figure here.

There are two types of product come out of China. One is the generic,
which is what Walmart and its clones sell. Then there is the bespoke
product that is made to spec. The lamps I use are made to spec.


Posted by Neo on February 23, 2010, 1:33 pm
 




Lumen output decreases over the distance (exponentially) so the
usefulness of a lighting element or fixture is measured by the
Lumen output it can deliver across a distance. If a LED element
overheats its Lumen output drops. This technological characteristic
has been reported to effect early high power 3W LED elements
used by Flashlight which had heat dissipation problems after
15minutes to 30 minutes of use.  This survey of high powered
LED flashlight was pretty consistent[1] . in that for the 15 minutes
all
the unit performed at 100% Lumen output but by 60 minutes
most LED flashlight were only operating at about 50% their
specified Lumen output. IIRC the author of this survey/report
believed that inadequate heat dissipation was effecting
the LED's lumen output performance. However, the author
felt that the extended battery performance of LED flashlights
gave them a unique advantage over the conventional Zenon/Argon
incandescent bulbs flashlights. I personally never use a flashlight
for over 5 minutes so it was a no brainer for me to retrofit one
of my MAG-LITE flashlight with a 3W LED bulb.
With the exception of my 3W LED MAGLITE - the light
output from my other LED flashlights is very weak compared
to my incandescent and CFL flashlights.

Most of the reviews I've read of the Coleman LED camping
lanterns suggest that the lumen output of only one or
two *high Lumen* LEDs are still inferior to CFL camping lanterns.


[1] http://www.flashlightreviews.com/index1.html

Posted by Josepi on February 23, 2010, 3:23 pm
 

Lux output drops over distance. I don't believe lumen output changes. As the
lux drops the area increases.



Lumen output decreases over the distance (exponentially) so the
usefulness of a lighting element or fixture is measured by the
Lumen output it can deliver across a distance. If a LED element
overheats its Lumen output drops. This technological characteristic
has been reported to effect early high power 3W LED elements
used by Flashlight which had heat dissipation problems after
15minutes to 30 minutes of use.  This survey of high powered
LED flashlight was pretty consistent[1] . in that for the 15 minutes
all
the unit performed at 100% Lumen output but by 60 minutes
most LED flashlight were only operating at about 50% their
specified Lumen output. IIRC the author of this survey/report
believed that inadequate heat dissipation was effecting
the LED's lumen output performance. However, the author
felt that the extended battery performance of LED flashlights
gave them a unique advantage over the conventional Zenon/Argon
incandescent bulbs flashlights. I personally never use a flashlight
for over 5 minutes so it was a no brainer for me to retrofit one
of my MAG-LITE flashlight with a 3W LED bulb.
With the exception of my 3W LED MAGLITE - the light
output from my other LED flashlights is very weak compared
to my incandescent and CFL flashlights.

Most of the reviews I've read of the Coleman LED camping
lanterns suggest that the lumen output of only one or
two *high Lumen* LEDs are still inferior to CFL camping lanterns.


[1] http://www.flashlightreviews.com/index1.html  



Posted by ghio on February 24, 2010, 11:48 am
 


The thing about LUX and Lumins is that, like all such claims, they are
only used to impress with numbers. What I do is is empirical testing.

empirical - adj: Derived from experiment and observation rather than
theory. Or, in a more vernacular vein, "Suck it and see testing".

Those that work get used, those that fail to deliver, well, they go in
the box of LUX and Lumins claims. It really is quite a full box these
days.

I have five 14 LED flashlights. With good batteries they put out a
good light for long periods. Then if you want to blow your Coleman
lamp out of the game you can use something like this camping lamp (new
pick at)

http://s78.photobucket.com/home/GGhio

Which put out a fantastic amount of light.


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