Cree PAR38 LED spotlight.

[DavidCampen]

Today I purchased a Cree LED lightbulb (13.5 watts) from Home Depot for about $0.55 per watt. Prices are dropping significantly. So I decided to look for a Cree spotlight. Here we have a Cree (18 watt) PAR38 spotlight for $1.50 per watt.
Cree 90W Equivalent Bright White (3000K) PAR38 27 Degree Spot Dimmable LED Spot Light Bulb (3-Pack)-BPAR38-1503027T-12DE26-1U100 - The Home Depot
I used to figure about $5 per watt for a quality brand LED light. This price for the Cree spotlight is a significant reduction.

[naoki]

I've used Cree 9.5W & 18W Warm/Soft white, and they work well. For some reason, flood type Cree has lower lumen/W (83.3 lumen/W for flood, and 88.9 lumen/W for the round, A-type bulb). I've been using the A-type because the fixture I made is side mounting. Flood type is better for our purpose, though, since all light goes toward front, and it doesn't suffer from reflector loss.

Cree has 13.5W bulb? Is it the newer 4-flow kind, which is really cheap? It seems that the goal of this new one is to cut the cost (there is a video review to show the internal in youtube). It has shorter warranty (3 vs 10 years), and lower efficiency than the one with metal heatsink at the base.

I placed an order of this ($2.57 for 12 W):
Wholesale Product Snapshot Product name is High quality SMD 5730 E27 12w 110V led bulb 5730 36LED E27 led lamp Warm white /white,5730 SMD E27 candle chandelier

It shows 106.7 lumens/watt, but I don't have high expectation (usually those cheap LEDs don't tell the true spec, and aren't worth buying for plants). But it's cheap, so I ordered them just for fun.

[DavidCampen]

Naoki, as you know, lumens is a measure of the light's efficiency for human vision, so, for white phosphor LEDs, there is little or no correlation between lumens and PAR (Photosynthetically Active Radiation). For LEDs without phosphor the correlation would be negative.

I don't understand your argument as to why flood is better than spot. For LED lamps of both types, flood and spot, I would expect that they are using a Total Internal Reflectance (TIR) lens for focus and not reflectors.

---------- Post added at 03:18 PM ---------- Previous post was at 02:55 PM ----------

Originally Posted by naoki

I've used Cree 9.5W & 18W Warm/Soft white, and they work well.
...
Cree has 13.5W bulb? Is it the newer 4-flow kind, which is really cheap?

Here is the 13.5 watt, 1100 lumen bulb that I purchased:
Cree 75W Equivalent Soft White (2700K) A19 Dimmable LED Light Bulb-BA19-11027OMF-12DE26-1U100 - The Home Depot
They were on sale for $7.97. They have a 10 year warranty.

At a price of less than $1 per watt for the Cree LED bulbs, as the CFL and incandescent bulbs in my house fail I will replace them with Cree LED bulbs.

[naoki]

That's a good deal for the 13.5W Cree! I didn't think that it is the original style with heatsink base because the price you mentioned was too good.

I meant flood or spot is better than A-type (the one you bought) for plant application. The light is getting emitted to almost 360 degree with A-type bulb, so it doesn't have the advantage of directional emission.

I agree PAR is better than lumen, but I was comparing Cree warm white A-type vs Cree warm white flood (PAR38). So I'm assuming that the phosphor is similar (i.e. the emission spectra are similar), but lumen/W is different.

[DavidCampen]

Here is a PAR38 spotlight from another vendor. Home Depot is selling them at a discount price. I ordered 6, I hope that they are of decent quality.
TCP 120W Equivalent Soft White (2700K) PAR38 Dimmable LED Narrow Flood Light Bulb-LED19E26P3827KNFL - The Home Depot

[ALToronto]

David, your most recent choice is a good deal - almost on par with Aliexpress pricing. It's still a little better if you buy direct; you can usually get them for $9-10. The light bulbs in your first post, however, are considerably marked up by HD - online, they're about $3-4 each.

So far, my experience buying directly from the manufacturers has been very good. You do need to shop around, though - the prices can vary dramatically.

Everybody seems to be using either Cree or Epistar/Bridgelux. Are they of comparable quality, or is Cree noticeably better? I've also been searching by lumen efficiency - 80 lm/watt seems to be standard, but you can find up to 135 lm/watt. Is there any validity to these ratings, or is it an unreliable measure, as David says?

[DavidCampen]

Originally Posted by ALToronto

... The light bulbs in your first post, however, are considerably marked up by HD - online, they're about $3-4 each. ...

13.5 watt A19 LED bulbs for $3-4 each? Where pray tell? Glancing at Aliexpress I did not see any near that price.

[ALToronto]

David, go to aliexpress.com and search for:

"Led light bulb cree e27 15w"

You will find lots of choices in that price range, with free shipping to North America. You may need to buy a minimum of 10 bulbs to get that price.

[ALToronto]

David, I just noticed the A19 designation for the HD lightbulb you bought. I looked for A19 bulbs on aliexpress, and you're right, they are more expensive. However, aside from the cool led 'filaments' on some models, I don't see much difference between the A19 bulbs and the ones without that particular designation. Certainly no difference in lm/w efficiency.

I just bought 12 w incandescent replacement light bulbs for general lighting in my house (not A19). $52 for 15 light bulbs, free shipping, all 5-star reviews for the vendor. We'll see how they work out.

[Kino]

Hello there, I am a neo-phyte with my lighting needs. I think I will need LED bulb(s) and would like to clamp them on to my rack. Just wondering, if I do not wish to use reflectors, what would you folks recommend for mounting? Thank you for helping out a newbie!