Cree price

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gar

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Ann Arbor, Michigan
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141109-2932 EST

Today at Home Depot a Cree soft white LED 60W was just under $5 and with tax just over $5. I believe this is subsidized by DTE.

Bought one for test in my range top hood. Should not be a problem because there is good air flow even with the fan off, and bulb axis is horizontal. However, when the range is in use the ambient is higher, and there may be a lot of moisture at times,

I have previously had failure of a 9.5 W Cree (60 W equivalent) in a more mild environment.

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gar

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141110-0852 EST

I have previously calculated a cost of operation comparison of incandescent, CFL, and LED bulbs. The calcuklation is per 1000 hours of operation, and includes the capital cost as well as energy cost. My energy cost rate is $ 0.16 / hour.

60 W Phillips incandescent ---- $ 10.06 / 1000 hours
19 W CFL --------------------- $ 3.19 / 1000 hours
9.5 W Cree about Dec 2o13 --- $ 2.07 / 1000 hours
9.5 W Cree yesterday --------- $ 1.72 /1000 hours

These are approximately comparable in light output.

By the expenditure of $ 5 yesterday for the Cree 9.5 W bulb and using it in place of a 60 W incandescent I will pay for the purchase of the Cree in about 520 hours by the reduction in energy use. The incandescent is a 0.06 kW load. The kWh that equals $ 5 is 5/0.16 = 31.25 kWh. The incandescent uses $ 5 of energy every 31.25 / 0.06 hours = 520 hours.

I usually leave the stove light on about 3 to 4 hours per day. Thus, in about 520 / 4 = 130 days I pay for the capital cost of the LED. Good return on investment if the bulb has a good life in the environment.

I believe my math is correct.

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dfmischler

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Sorry for the late post... just caught up with this.

I have had one Cree LED lamp failure so far. It was a soft white 18W 1600 lumen bulb (their 100W equivalent). It had been installed in a non-enclosed horizontal fixture with a standard lamp shade over it (so air could flow around it). How is your horizontally mounted stove light doing?

I saw some of the new Cree 4Flow bulbs yesterday at Home Depot. The demo fixture was not operating when I was there. There are ventilation slots cut into the plastic bulb-shaped casing, so I'm pretty sure it isn't usable in damp locations like the earlier Cree lamps. Anybody got any experience with those yet?

The easiest payback I have calculated so far is for use of the Cree 75W equivalent bulbs (13.5W and 1100 lumens with a CRI of 80) in basement walk-in coolers for fruit and flowers where the lamps run about 9 hours per day. The original 100W incandescent bulbs added a lot of extra heat, and CFL's never really worked right in that environment, and the floral designers who use the space hated the poor color rendering of the CFLs. They kept trying to put brighter lamps in (e,g, 200W equivalent CFLs) thinking that the reason that they couldn't see the colors they wanted was because the lights weren't bright enough; I think they had no idea that the colors they wanted to see simply weren't in the lamps' spectra...
 
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Dennis Alwon

Dennis Alwon

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LED prices have dropped considerably. We have been using Philips bulbs and the R30 10.5 watt bulbs have come down from $30 or so to $12. Our poco is offering incredible deals to customers but we are limited to 15 bulbs. I purchased 15 of the R30 LED bulbs for $6
 
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gar

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Ann Arbor, Michigan
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EE
141221-0942 EST

dfmischler:

My Cree in the vent hood over the range top is working fine.

The $ 5 each price at Home Depot for the 9.5 W Cree has now gone to its new normal price of between $ 6 and & $ 7.

Unless you have an incandescent light source, or other continuous spectrum source, then you won't have correct color rendition for all persons. CFLs, LEDs, and phosphor light emitters are all narrow band light emitters, as are gaseous discharge devices. Human eye color response is not identical for all persons. Thus, how the narrow bands in the light source correlate with the narrow band receptors in an individual person determines how that person sees a color.

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dfmischler

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Western NY
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Facilities Manager
gar said:
Unless you have an incandescent light source, or other continuous spectrum source, then you won't have correct color rendition for all persons. CFLs, LEDs, and phosphor light emitters are all narrow band light emitters, as are gaseous discharge devices. Human eye color response is not identical for all persons. Thus, how the narrow bands in the light source correlate with the narrow band receptors in an individual person determines how that person sees a color.
Click to expand...

Agreed that the spectrum is not as good as incandescent, but I think it is significantly better than the CFLs. I have heard no complaints about the Cree lamps and they have been in there for a few months now (and I didn't say anything when I put them in: the complaints just stopped).

This link shows spectra for some lamps. It shows the Cree TW LED spectra being a little notchy but not nearly as banded as CFLs (if you know what I mean). Exactly how that relates to the "standard" Cree soft white spectrum I don't know. I would love to see a good spectrum for those but haven't been able to find one, and I don't have the equipment to check it myself.
 
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GoldDigger

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Dennis Alwon said:
The 2700K bulbs are darn close to incandescent and the 3000K are similar to Halogen
Click to expand...
Halogen is a pure "black body" spectrum just like any other incandescent, just with a higher filament temperature.
(Assuming you are not dealing with phosphor or glass transmission or dichroic coating modified incandescents in the first place.)
 
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