Re: LED interior lights
- From: shekhar.gods@xxxxxxxxx
- Date: Sat, 27 Sep 2008 00:23:27 -0700 (PDT)
On Aug 19, 12:09 am, Neon John <n...@xxxxxxxxx> wrote:
On Sun, 17 Aug 2008 22:25:17 -0400, LouB <L...@xxxxxxxxxxx> wrote:
SomeLEDbulbs will melt the diffuser cover, so be very careful
I doubt it. LEDs consume very little power. Perhaps theLEDpackage
containing dropping resistors get warm but not the bulbs.
---
$$$$$$$$$%%
Yours truly, Johnny Dollar!
LEDs are NOT going to burn anything!
You wouldn't want to bet on that, would you?
THe following is from this site:
http://www.ccrane.com/lights/led-light-bulbs/led-lighting/index.aspx
Citing C Crane as an authority is like citing Wikipedia - risky. Remember,
he's Art Bell's guy. And you can bet that anything he sells will be
over-priced and under-speced. Like this one
http://www.ccrane.com/lights/led-light-bulbs/cc-vivid-plus-led-light-...
$30 friggin' dollars for a $5 item? Geez.
Good rule of thumb with LEDs. IfmultipleLEDs are used, especially the 5 or
7 mm round ones then the device will perform poorly and be a power hog. That's
just the way it is. The high performance die and phosphors go in the star
configurations.
Why LEDs?
AnLEDlight bulb can last you up to 30,000 hours. That averages out to
6 hours of light per day for 12 years.
Geez, I can't believe anyone is still quoting that marketing.... Oh hell, call
it what it is - a lie. SOME low power monochromatic LEDs (like the little ONledon your TV set) MAY "last" that long, "last" meaning down to 50% of the
original output.
POWER leds, the ones that make useful light, are specced at hundreds of hours
at full rated output. Sometimes a couple of thousand. Luxeon specifies their
flashlight grade (highest output) at something like 300 hours (can't recall
the exact figure without looking but it is less than 500). In reality, they
don't even last that long.
If you go tohttp://wwww.candlepowerforums.comand look in theLEDsection,
you'll see where some very sharp engineers have run and are continuing to run
life cycle testing. NOT accelerated testing from which some of the worst of
the lies result from. Actual calendar life testing. It doesn't take long.
Even the best illumination LEDs only last a couple of thousand hours. There
are micrographs and cross-sectioned failed LEDs that show the failure
mechanisms.
LEDlight bulbs are so energy efficient that, depending on how often you
have them on, they'll actually pay for themselves in just over a year.
This is just plain silly. LEDs have just broken the 100 lumen/watt benchmark
and that is only for the most expensive high end chips. CFs have been above
140 lumens/watt practically since the beginning. T8 tubular fluorescent lamps
using rare earth phosphors are right in there.
Just to show how silly this claim is, let's look at the "Vivid plus" light
that C Crane is peddling. They claim that it's a reading lamp. Most reading
lamps spec no more than 60 watt bulbs, though most of us use 100 watters :-)
Let's follow instructions and go with 60 watt. That's the best case scenario
for the Vivid.
Here's GE's spec for a plain old 60 watt bulb
http://genet.gelighting.com/LightProducts/Dispatcher?REQUEST=CONSUMER....
Rated life is 1000 hours at 120 volts. 865 initial lumens. 14 lumens per
watt. It costs about a dollar. Let's use 10 cents a kWh for power costs.
Over its 1000 hour life, the GE lamp uses 60 watts * 1000 hours = 60kWh.. At
10 cents a kWh, that's $6. Total life cycle cost for that lamp is $1 for the
lamp and $6 for the power = $7.
The C Crane light costs $30 and is claimed to use 1.86 watts. A claimed 60
lumens (probably not but we'll go with that.) That's 60/1.86 = 32 lumens per
watt, only twice as good as the plain old incandescent.
Over the same 1000 hours that the incandescent lamp lasted, the power usage is
1.86 watts * 1000 = 1.86kWh * 10 cent/kWh = 19 cents.
Let's be real generous and assume that theLEDlight lasts 10,000 hours.
According to the CPF testing, that type ofLEDwon't but let's give it the
benefit of the doubt.
1000 hours is 1/10th of the total light so we'll allocate 10% of the
acquisition cost to the 1000 hours. $30/10 = $3. Life cycle cost for thatLEDis $3 + $0.19 = $3.19.
At this point we can draw some conclusions:
- TheLEDlamp puts out a little less than 10% of the incandescent lamp. The
incandescent lamp's light output is essentially omnidirectional but a good
luminaire will recover at least half that light and project it in the desired
direction, assuming directionallightingis desired.
- Its acquisition cost is about 30X that of the incandescent lamp.
- TheLED's1000 hour life cycle cost is about half that of the incandescent
lamp.
A year has about 8,760 hours in it. If both lamps were left on all the time
then the incandescent lamp would use 60 * 8760 = 525kWh. At 10 cents a kWh,
that's $52. TheLEDlamp would use 1.86 * 8760 = 16.30kWh, $1.63.
The incandescent cost for the year would be 9 bulbs (assuming 1000 hours) = $9
so the total cost is $52+9 = $61. TheLEDwould be $30 + 1.63 = $31.63. So
in this best case scenario (for theLED), the total operating cost for a year
would be about half. It would appear that theLEDhas the edge. Not so fast.
TheLEDonly produces about a tenth (60/865 lumens = 7% actually) the light
output so we'd need 10 of theLEDlights to equal 1 incandescent lamp. That
would put theLEDper-year cost at $31.63 * 10 = $316.30. Hmmm, not so hot.
One could argue truthfully that the incandescent light loses output over its
life from bulb darkening which is true. At end of life, the rule of thumb is
that the output is down by half. Let's assume that its average output is only
half. That means that we'd only need 5LEDlamps to compete with this
half-output. That's $316.30/2 = $158.15.
More conclusions for lamps burning 100% of the time over a year.
- TheLEDcost for the same amount of light is $158.15/$61 = 2.6 times as
much.
- TheLEDside, requiring 5 fixtures, would spread the light out over a larger
area, reducing the specific illumination.
- The cost of the 4 extra fixtures and wiring is not included in this analysis
but would be significant.
This is the best case for theLED. If we assume something more reasonable
like 4 hours of use a day, every day, for a year, that's only 1,460 hours..
Only 2 incandescent lamps would be needed. The initial cost of theLEDlamps
would overwhelm the savings.
That's not even the end of the story. GE makes a halogen version of the 60
watt bulb called the Reveal A19 halogen
http://genet.gelighting.com/LightProducts/Dispatcher?REQUEST=CONSUMER....
It has a 3000 hour rated life and a lumen output of 800, about the same as the
incandescent lamp. More importantly, it maintains that output over the life
of the lamp. The output is slightly less because the didymium glass that
filters out certain yellow wavelengths absorbs some of the light.
This lamp costs about $3 at Wal-Mart. The cheapest that I could find it
online was $7 for a 4-pack or $1.75 ea. The cost per hour of life therefore
is from the same as the ordinary incandescent to about half, depending on
where you buy it.
The best way to conserve energy is to use less of it.LEDlight bulbs
are directional - which means that they only put the light where you aim
it or where you need it. Incandescent bulbs, on the other hand, just sit
there and throw their glow all over the place - wasting electricity and
generating heat.
Only if you compare apples to oranges. If you compare anLEDlamp such as the
one above to an MR or PAR lamp, things look a bit different. The GE EXT/CG
MR-16 30 watt, 12 volt lamp that I use in my RV's reading light has a 5 degree
beam-spread. A singleLEDin an appropriate reflector can compare to that but
the cheap-sh*t, overpriced crap that C Crane sells certainly can not.
LEDlight bulbs run cool, so they're safer to use than fragile, burning
hot halogen and incandescent bulbs.
AnLEDof comparable light output runs cooler than an incandescent lamp but
only marginally so. The MR type halogen lamp has a diachronic reflector that
reflects visible light but passes most of the infrared (heat) out the back.
One can hold his hand in front of the 30 watt lamp in my reading light for an
extended time without being burned. There is little if any difference in
"safety" between the two. Neither will burn you when operated normally.. Both
will overheat if covered up. The edge may very well go to the halogen lamp,
since theLEDis made of flammable plastic and stuff.
I point out the last part just to show how silly this "safety" argument is.
LEDs turn on instantly - which has been a big benefit in car brake
lights and is also a welcome feature when testing lights in a dark basement.
"Annoying" is a better word for it. The "study" that claims the instant-on
feature ofLEDtail-lights imparts some safety benefit is highly flawed, to
the point that no conclusion can be made. Subjectively, I'm mildly startled
and a bit annoyed by the instant-on and if anything, that momentarily
distracts me from the task at hand - stopping quickly.
LEDs do not use mercury like CFLs - so disposal concerns aren't the same..
If you're "concerned" by the tiny amount of mercury in CFLs then you must be
equally concerned about the arsenic and other toxic materials used to make the
LEDs. "Concern" in either case would more accurately be described as a phobia
since the concern has to do with imaginary risks.
----------
I'm anLEDfan and as such I know their limitations as well as their benefits.
Proffering myths as in the above does the technology no good and indeed,
causes harm. In the sign business there is now a backlash against LEDs
because of how they were over-hyped. When the claimed "50,000 hour life"
turns out to be less than a year, the sign shop that has to replace the damned
things under warranty is pissed. Especially since the LEDs are usually sold
as competing against neon which really does have an infinite life if properly
made and installed.
SuitableLEDlamps can be had for RV use but not from scammers like C Crane..
Here are two places that I buy from:
http://www.qualitychinagoods.comhttp://www.dealextreme.com
Both are located in Hong Kong and offer free shipping. I advise avoiding themultipleLEDlights in favor of the single high powered (1 to 5 watt) LEDs
mounted in reflectors and sold as assemblies. Few come with RV-type lamp
bases but that's actually good since if the lamp assembly is soldered in,
there is no problem with contact corrosion or vibration.
THE most efficient illumination (at least that any mere mortal can buy) is
still the CF lights, with rare earth phosphor tubular lights roughly equal.
That's why all the generallightingin my RV is fluorescent (or neon that I
made using white phosphor.) I do use LEDs for some spotlighting. I'll
probably replace the halogen MR lamp in my reading light with a high poweredLEDlamp as soon as the new batch of round tuits come in :-)
John
--
John De Armond
See my website for my current email addresshttp://www.neon-john.comhttp://www.johndearmond.com<-- best little blog on the net!
Tellico Plains, Occupied TN
Remember, amateurs made the Ark, professionals made the Titanic.
.
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