In its eagerness to win the race to the bottom, Cree may be letting a few things get away from it.
This past week, in relation to a client effort, I bought a variety of latest LED lamps and dimmable CFLs at Home Depot and Lowe's. Included in that group was the relatively new Cree 75-Watt-equivalent, 1100-lumen lamp. (I'll look at the new 100W version as soon as it's available in the stores.)
What I have observed is a bit of a good news/bad news scenario. First, the good news about the unit: Like the 60W equivalent, it includes the "black hole" light pattern resulting from the internal LED-tower approach.
It turns out that a surface directly above the lamp will be illuminated just fine, in foot-candles, to within 25-30% of any side surface. In other words, even though you can perceive a center dark spot, it really has little perceived effect on the light emission pattern compared to a near-perfect spherical pattern. It is unlikely (though possible) that the bulb would be used where a person would to be looking straight into the top of the bulb and have reason to say, "I don't like how it looks." This certainly wouldn't be the case in a table lamp application.
Knowing the flak Cree has taken for this design, I was about to suggest it was dumb like a fox, since the design allow the company to supplement the outer heat sink housing with the internal tower for heat sinking purposes, in turn letting it move toward higher power.
But I decided to conduct a couple of additional routine tests. I observed that the bulb seemed to be surprisingly white for 2,700K -- even a little toward the blue. In an earlier blog on the Philips SlimStyle lamp, I mentioned that, in the Home Depot side-by-side demo with a Philips 60W, 2,700K incandescent, my wife and I perceived the Philips LED bulb as being whiter, even though I verified that the LED lamp from Philips (this site's sponsor) is indeed at 2,700K CCT, with spectral differences perhaps accounting for the different perception.
So I figured perhaps the same thing was happening here. However, I found that the CCT of the Cree 75W is actually 4,400K -- even though the Lighting Facts label clearly said 2,700K. It looks like the product manager's name might be Pinocchio. How did this happen? So much for Lighting Facts labeling.
I then decided to conduct a little temperature testing, and I found that there is a 55°C temperature rise in the outer aluminum heat sink portion, putting the case at 80°C in a 25°C ambient. (A shaded table lamp typically runs a few degrees hotter.) That in turn means that all the driver electronics, with its IC, capacitors, etc. inside the housing, will be in an ambient of at least 80°C. That contrasts with the Philips SlimStyle, in which the driver circuitry is to a very substantial degree thermally isolated from the heat sink and LEDs. Needless to say, I can't wait to take a look at Cree's 100W bulb.
It's never surprising when some managers at a large public company, partially driven by their stock option valuations and facing extreme price and "newness" pressures in an ever-changing competitive environment, start loosening the reins on what some of their lower-level marketing and design troops are doing.
But that doesn't mean it's a good idea.