Re: LED light results -- short

On Thu, 30 Mar 2006 06:54:43 -0800, "Dusty"
<RV_phixer@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:

"Neon John" <no@xxxxxxxxx> wrote in message
news:bopm22p1jshj9u554du015m399b0e70ka1@xxxxxxxxxx
...
Actually, LEDs are a poor way to go for boondocking. They're only
a
little more efficient than incandescents.
Huh? "Neon John", this flies against everything I thought I knew
about LED's. I've done the math...and I don't follow you. Could
you please elucidate?

Sure. Here's a table that I put together from published
manufacturer's data about a year ago:

Lighting efficiencies - Initial lumens per watt. Conventional
ballasts where applicable.

High pressure sodium-- approx 125 lumens/watt (Osram)
Low pressure sodium-- 150-180 lumens/watt
HID-- 80 to 110 lumens/watt*
Automotive D2S 35 watt HID 91 lumens/watt
Solarc low wattage HID 45-60 lumens/watt
32 watt T8 fluorescent-- 85 to 95 lumens/watt
standard F40T12-- 60-65 lumens/watt
compact fluorescents-- low 30's to low 60's lumens
per watt, usually 48-60
Sulfur lamp-- 53 lumens/watt
Tri-phosphor neon-type cold cathode-- 60-80 lumens/watt
T3 tubular halogen-- 20 lumens/watt
white LED-- 15-19 lumens/watt
standard 100 watt incandescent-- 17 lumens/watt
incandescent night light bulb (7w)-- 6 lumens/watt
incandescent flashlight bulbs-- less than 6 lumens/watt

* HID lamps and ballast designs vary widely.

I put this chart together to use in countering the outright lies that
some LED sign suppliers are telling to try to compete with neon.
Unfortunately LED vendors, even some otherwise reputable ones, are
simply lying about efficiency.

Another issue seldom mentioned for LEDs, particularly the high power
and phosphor-based ones, is the dimming curve. High power and
phosphor LEDs are not like those "last forever" low power LEDs in
calculators and pilot lights and such. According to the ISA
(International Sign Association - neutral as far as lighting
technology goes), some LEDs are down to half the initial output in as
little as 1000 hours. Few go beyond 7-8khours to half output.

Since I put this chart together, LEDs have gotten a little better,
phosphor-free Tri-Die white LEDs have come to market, CFLs have
improved a bit, CCFLs have come along and low pressure sodium lamps
with better color rendering but with about the same efficiency have
become commonly available. Still this chart is highly representative.

You'll notice that any of the fluorescents are many times better than
LEDs and that LEDs are on par with medium sized and larger
quartz-halogen incandescents. Only in the small sizes where envelope
and filament holder quench greatly affects the incandescent's
efficiency are LEDs superior. For general area lighting, LEDs are
pigs - about equivalent to halogens.

If you want a point-source of light, say, a reading light or to
illuminate a spot outside at your campsite, you'd be better off
efficiency-wise with one of the SolArc small HIDs. Here is a nice
little 13 watt unit, the first item on this page:

http://www.trailtech.net/motorcycle_hid_parts.htm

I have two of these lights. One, with the spot reflector, is the
headlight on my electric scooter. The second, with the flood beam
replaced a 55 watt halogen lamp as my reading and general campsite
light. It provides enough light for general activities throughout my
entire rig.

For all other types of lighting, inverter-driven CFLs provide the best
bang for the buck. 12 volt versions are available but they're not
worth the extra money, considering how cheap small inverters are now.
After I get some of the CCFLs to evaluate, I suspect that I'll be
recommending them instead of CFLs for RV use.


The way to go for low power is with fluorescents. Especially the
compact fluorescents because the rare earth tri-phosphors they use
are
more efficient than the old halo-phosphates that most conventional
fluorescent lamps still use.

Yeah. They are better than incandescents. But only by a rather
small percentage when compared to the LED's that I knew...

Oh, just a factor of 3 or better.

John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
.

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