Cree PAR38 LED spotlight.

[naoki]

XM-L2 must be very nice! Is it 5000k? Which 660nm are you using? BTW, if you have Apogee sensor, it probably underestimate the PPFD. I think 660nm is pretty close to the sensitivity drop off of this sensor. I'll be looking forward to hearing about your new fixture!

[ALToronto]

Originally Posted by This Side of Paradise

One easy way is to use a meter(kill a watt is one brand name) that you just plug the unit into.
Altoronto if you want to borrow mine you are welcome to, my guess is you in the Toronto area

I'd love to get together! Are you planning to go to the SOOS show in 3 weeks? I'm exhibiting my living wall (and its light fixture), and giving a presentation on LED lights (a very basic one).

Let me know if you're going, and I will probably go to the COOS show at the end of the month.

[jmmehler]

Someone please help me understand why the cree bulbs are better than the 100w (23 watt) cfl bulbs. I believe the cfls put out about 1600 lumens and come in a variety of temperatures. Only difference is that they are much cheaper, and not dimmable.

[naoki]

Originally Posted by jmmehler

Someone please help me understand why the cree bulbs are better than the 100w (23 watt) cfl bulbs. I believe the cfls put out about 1600 lumens and come in a variety of temperatures. Only difference is that they are much cheaper, and not dimmable.

I think you are talking about Cree household Light bulbs (efficiency of DIY Cree LED is at the different league). lumen isn't good for comparison of different types of light, but LED light bulbs can give a bit more lumen per watt.

With light for orchids, you need to look at the total cost instead of the initial cost. Frequently, a bit increase in the efficiency can pay off the difference in the initial cost. Kill-a-watt meter is useful to realize this. I think my cost of electricity for orchid lighting is between $500-1000 per year at this moment (around 38 sq ft of space).

Also, with the florescent light, the decay in light output is steeper compared to LEDs. So initially it might be 1600lm, but you could be getting lower output within a couple months.

Also, warmer LEDs (lower K like 3000K) have nice emission spectra with good amount of red for efficient photosynthesis.

I did rough comparison of PAR with CFL vs LED vs incandescent light from my measurement. If I can find the data, I'll post them. I vaguely remember PAR/W of incandescent light was pretty similar to CFL. But I don't remember the details of CFL vs LED.

[ALToronto]

Originally Posted by jmmehler

Someone please help me understand why the cree bulbs are better than the 100w (23 watt) cfl bulbs. I believe the cfls put out about 1600 lumens and come in a variety of temperatures. Only difference is that they are much cheaper, and not dimmable.

Why do you say that LED bulbs are more expensive? Only if you're buying retail. Read through the earlier posts in this thread - retail store markups in North America are 500 - 1000% over online prices. And the quality of the light is much better with LEDs.

[naoki]

Here are some measurements from those screw-in light bulbs. I put them in the cheap 5.5" clip light. Measurement taken at 12" from the tip of the light bulb. Note that the measurement is taken at a single point, so it may not represent the total output.

Type	Bulb	Age	watt	PPFD	fc	PPFD/fc	PPFD/watt
LED:A	1	0	18.9	83	458	0.18	4.39
LED:A	2	0	19	83	544	0.15	4.37
LED:A	3	1yr	9.8	39.5	220	0.18	4.03
LED:A	4	1-2 mo	10.1	28.2	189	0.15	2.79
CFL:F	5	unknown	17.2	19.2	122	0.16	1.12
CFL:F	6	unknown	18.5	24	149	0.16	1.30
CFL:A	7	1-2 mo	14.7	18	70	0.26	1.22
Inc:F	8	unknown	63.9	71	322	0.22	1.11

Type: 'Inc' means incandescent, 'A' means A-type bulb (the normal, roundish kind), 'F' means flood light type.

Light Bulb model/ID:
1: Cree 18W Soft White Standard A-type, 2700K
2: Cree 18W daylight Standard A-type, 5000K, 150mA, BA21-16050OMF12DE26-1U_00, E330248, 4514
3: Cree 9.5W Soft White, 2700K, 79mA, BA19-08027OMF-12DE26-2U_00, 2713, E330248
4: Philips 10.5W, 5000K, 95mA, 3PM5
5: Commercial Electric, 16W, 240mA, SKU#773-972, Model: EDXR-30-16, V#42836
6: Commercial Electric, 19W, 320mA, SKU#773-239, Model: EDXR-40-19, V#42836
7: Energetic FE153, 13W, 175mA, Red light, not white
8: GE, Miser Flood 65W

watt: actual watt measured with Kill-a-watt

PPFD: micromol/m^2/s, photosynthetic photon flux density measured at 1' with old Li-Cor LI190. Not calibrated, so blue sensitivity may be a bit weaker. Here is some easy explanation of PPFD

fc: footcandles measured at 1' with cheap LX-1330B

PPFD/Watt column is a proxy of efficiency and it is what I (and you should) care most. The unit is micromol/m^2/J (but I'll omit the unit for the discussion below.

1. There is a big variation among LED. Cree is getting > 4 efficiency. Cheap Philips is only 2.79. I'll be getting cheap eBay LED bulbs tomorrow, which Alla is talking about. I'll measure them, but it is probably not worth getting (hopefully I'm wrong about this). The other issue with those cheap LED bulbs is the durability from what I hear.

Note that Philips do make good LED, but the model I tested is the cheap kind.

2. Note that Cree soft white (2700K) and daylight white (5000K) has the same PAR output. This means that 2700K, which has more red light, is more efficient in terms of photosynthesis.

3. Even the cheap LED seems to be better than CFL. Note I didn't have white A-type CFL, and I used flood type.

LED 2-3 times more efficient than CFL. This seems to be a bit too high, though. This could be the difference in the beam spread, so my estimate may not be representing the difference at the total output level.

4. CFL and incandescent flood lights have similar efficiency in terms of PAR.

5. I was somewhat surprised that Red CFL is giving decent amount of PAR (comparable to white CFL).

[ALToronto]

Naoki, I don't do ebay. The lightbulbs I'm getting claim to contain CREE chips, so we will see. They're coming directly from the factory in China, and will not be packaged in pretty bubble packs with flashy labels and instructions in 3 languages. I suspect they will be either in plain white boxes or all in the same box, with foam mesh sleeves, like asian pears in a grocery store.

I will probably buy my own Kill-a-watt meter and test them out.

[DavidCampen]

Originally Posted by ALToronto

Why do you say that LED bulbs are more expensive? Only if you're buying retail. Read through the earlier posts in this thread - retail store markups in North America are 500 - 1000% over online prices.

That is one way to explain the price difference. Another explanation is that the inexpensive bulbs that you are buying through Alibaba are counterfeit and have inferior performance.

http://finance.yahoo.com/news/china-...055732036.html

[ALToronto]

Originally Posted by DavidCampen

That is one way to explain the price difference. Another explanation is that the inexpensive bulbs that you are buying through Alibaba are counterfeit and have inferior performance.

http://finance.yahoo.com/news/china-...055732036.html

The items I've received so far have given me no reason to suspect performance. Most counterfeit items have to do with consumer products - iPhone related, or designer labels. I'm sure that fake Cree chips exist as well, but if I'm spending 20% of the cost on 80% of performance, I'm still ahead.

As I've said before, I've bought brand name LED bulbs at Lowe's that were duds right out of the box. And that's for $10 each on sale - the same bulbs that would cost me $1.50 each on aliexpress.

Btw, a lot of products considered 'counterfeit' are made by the same factories as the real ones. This excess production is done clandestinely, without licensing fees being paid. But it's the same stuff.

[DavidCampen]

Originally Posted by ALToronto

Btw, a lot of products considered 'counterfeit' are made by the same factories as the real ones. This excess production is done clandestinely, without licensing fees being paid. But it's the same stuff.

Or, as is often the case for electronics components such as LED chips, the stuff going out clandestinely for resale are the rejects that did not meet the performance standards of the name brand and were supposed to be destroyed.