$8 for 60w or 40w equivalent, 2700k soft white Home depot
Cree Engineers a Cheaper LED Bulb by Losing the Heat Sink - ieee.org
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Seems to be XB-E or XB-G High-Voltage, Does not look like a MCPCB.
They are brighter too, right? I have one of the previous gen CREE 100w bulbs, but I would like something much brighter.
Currently 60w is the max in this new design, 815 lumens (old 60w is 800lm). Hopefully 100w will come soon.
I too would like brighter Cree bulbs. 150w, 200w, 250w please.
Yes, brighter! When I look at “replacement” wattage, I don’t think, as others do, “Same Light, Less Power” I think “Same Power, More Light”. I’d love to see some MUCH higher wattage LED bulbs. They need to be very bright, and dimmable by a normal, off-the-shelf slide dimmer. Also, don’t tell me that 800 or 815 lumens is a replacement for 60w incans. The incans are 880 lumens! Give me what you say you’re giving me, not something inferior!
I also think that greater efficiency should result in more light with the same power. Hopefully there will be a Cree alternative to this bulb.
I wonder how long it’ll take for one of these airflow-cooled bulbs to build up enough dust to block the vents or catch fire?
Does Cree say anything about the orientation of the bulb, or use in enclosed vs. open lights?
The illustration shows the standard table lamp, base down, unrestricted airflow.
$7.97 in California Home Depot right now.
The vents are on the top and the bottom of the bulb. Goal is to have air rise from one set of vents through the light to the other. Looks to me like it could be mounted vertically either top down or bottom up. I don’t think you’d get much convection if mounted sideways though.
The amount of airflow you’d get with convection is probably relatively small. Hopefully dust build-up wouldn’t be an issue.
Don’t quite understand about how the convection works. The LEDs really don’t sit on some heatsink at all? Is the convection done by some sort of active cooling?
And wait - 60W for 800+ lumens only? What kind of “efficiency” is that especially with multiple LEDs? I thought my Ultrafire C8 at 12W gives around 1000 lumens already?
No, it's a "60 watt equivalent" (i.e. equivalent output to a 60w incandescent). Package says "uses 11 watts".
-Garry
It's equivalent to a 60W incandescent bulb. It uses 11W.
From the description it sounds like the LED isn’t really mounted on a heatsink. Instead it’s just mounted on a circuit board.
Since the heat can’t go into a heatsink, the idea is that it is instead transferred to the surrounding air.
Hot air rises. So when the light is on awhile the air around the LED rises up through the vents above the LED and out of the bulb. The vents below the LED then draw in cool air from outside the bulb to replace the air that just left the light.
… and that’s the convection… the flow of air through the light to transfer the heat away from the LED.
Yeah, that would be nice. That bulb seems interesting, but the fan is worrisome. I also saw this: Amazon.com
That looks like it would make the perfect bug catcher here especially this time of the year.
Sorry about the 60W part, I missed that and thanks for correcting me. But putting out only 800+ lumens at 11W with 8 LEDs doesn’t sound really efficient either. What kind of LED do you think they use inside the bulb?
Thank you Firelight2 for explaining about the convection, and this is exactly what I understand about convection. Let’s assume they use eight XM-L inside the bulb, with 800 lumens that is equivalent to 100 lumens per LED - in other word each LED is only driven at about 0.25A. At current like this there is very less to no heat produced so using the convection method seems legit. However with all the 8 LEDs driven at this current we will only have about 6W in total instead of 11W isn’t it?
The IEEE article says the regular 60W equivalent bulb uses 9.5W, so there is a big drop in efficiency when the heat sink is lost. There are losses on the dome too.
While these bulbs produce much less heat than incandescent bulbs, I doubt you'll want to hold your hand onto the heatsink of a bulb that's been running for hours, especially if that bulb is under a bell.
Considering these things are selling for less than $8, I’d be very surprised if 8 XML leds are inside. I suspect it’s some other less-efficient LED.
They state 74.1 lm/W and 80 CRI which is not especially exciting but it’s obviously meant to be cheap…
I may be wrong, but I think you guys are comparing apples to oranges. You cannot compare a raw LED efficiency spec to an LED bulb efficiency spec. The bulb includes all losses such as driver inefficiencies,etc…
Spiders.
They will clog these vents with their webs and then dust/hair/zombies will stick to the webs.
Next thing Ya know, Jeb’s a Millionaire!
Bad design other than for in Hospitals, etc. where they have real clean air.
Later,
SpidyKeith
Out of curiosity, what kind of lifespan could I expect if I used these in areas where the bulb will get little to no airflow (like under a bell, as leaftye mentioned)? Would it fare reasonably well compared to a cheapo CFL?