I just tried out some 5W ‘corn cob’ LED cluster bulbs for the home - I installed 3 of them in a ceiling fitting - each bulb has 108 SMT ‘Warm White’ LEDs arranged in rows around the side of a plastic cylinder. I ordered them from China on eBay.
Initially, they were quite impressive - exceptionally bright, even illumination, although the colour was weird - not in the way the light itself looked - that was easy to perceive as white, but because (I suppose) it’s composed of just a few narrow-spectrum peaks, it just didn’t seem to illuminate non-white objects properly. The bulbs were too bright to look at, but the things in the room were dim.
A week later, they seemed to have lost more than half their original brightness and the colour changed to a sickly, indescribable hue (if there was such a thing as ‘bright brown’, this would be it). The effect of the illumination was similar to what you feel on coming indoors out of bright sunshine - you know the room is lit, but you just can’t make your eyes see.
I think the phosphors have just started wearing out - maybe the individual LEDs are being driven too hard.
I called a halt on the experiment and have switched back to CFLs (expecting that they will also lose brightness, but not in a week).
I’m now less than convinced that LED lighting will ever be ready for the job of living room illumination - it’s just not a comfortable, useful kind of light. It’s OK for accent and utility lighting - and coloured LEDs can be very decorative, but I’ve yet to see a decent, comfortable, attractive white LED - they’re all harsh or sickly (and as noted above, this is from someone who has adjusted comfortably to CFLs)
Is there a diffuser over the LEDs? I imagine it’s defective if it’s lost so much brightness that quick. But you might get better results if the light were diffused. Some of them have a plastic diffuser that’s shaped like an classic light bulb. I wouldn’t be surprised if the color was off, but I understood they should have plenty of the spectrum available, and a diffuser could balance that to something closer to an incandescent bulb.
Srsly. Buying 3 lamps from an un-named manufacturer in China, using e-bay as the purchase medium, you’re now dismissive of all LED home lighting? :rolleyes:
This is hardly my first encounter with LEDs - I’ve used them a lot as components, as indicators, in flashlights and in other forms of lighting, so no - that’s not really a useful summary.
There’s no diffuser on the lamps themselves, but they were installed within frosted glass goblets, but a diffuser isn’t going to correct colours if there are band gaps (or dips) in the output.
The fact that there were 108 emitters kind of screams “poor quality” to me. Cree makes quality emitters that can take several watts a piece, so even a 100 watt eqvivalent shouldn’t need anwhere close to that amount. It makes me think they bought a bunch of the cheapest possible LEDs they could find and threw them together for a “bulb”.
Still, I’m sticking with conventional incandescents and halogen until I’m convinced the bugs are worked out of LEDs. GE makes an LED bulb that shines light in all directions that I’m tempted to try, but the $30 cost is still too high for something to play with, and the color seems a bit “off”.
if they lost brightness that quickly, then I have to think that the LEDs are either being driven harder than they were designed for, or the bulb assembly has inadequate heat sinking for the diodes. given that they were cheap POS bulbs from China, that wouldn’t surprise me at all.
I have several of the Philips “Ambient LED” bulbs and they look just fine by my eye.
I only have one LED lamp. It’s a bedside reading lamp, which I’ve had for at least a couple of years. It’s quite bright, and I haven’t noticed a dimming in any way.
At present, I have only one LED bulb in the house, a Phillips which is in a reading light. It’s working out very well; the only drawback I’ve seen is that they don’t make an LED bulb which will work with an ordinary dimmer. I was warned at the Home Despot that if I wanted to put one in any circuit that had a dimmer, I’d have to replace the dimmer with a special one to go along with the LED. To do otherwise would be a fire hazard. I’m waiting to see which way the technology goes on this one…
I went to my local Lowes and checked out the LED lighting selection about two weeks ago.
Does anyone make an LED that produces the same output as a 100W bulb (approximately 1700 lumens)? They had a decent selection of LEDs, but they were all ridiculously dim - like 800 lumens or so.
Not quite yet. The bulbs available now generally top out at an equivalent to 60W incandescents. Switch Lighting evidently has 75W and 100W equivalent warm white LED bulbs, but I gather that they are currently test-marketing them to hotels and the like (their “Where To Buy” page says the bulbs are shipping to “hospitality properties”). They’re not available in stores yet, as far as I can tell.
With 108 LEDs in a 5 W bulb, each LED is using only 46 mW (and probably quite a bit less; I doubt such a cheap bulb even has a proper electronic ballast, instead using strings directly across the power line with perhaps a series resistor, like LED Christmas lights), suggesting that they used ordinary low power indicator type LEDs, although that should still be within their ratings, usually around 20 mA at 3.5 v or so (70 mW), but those type of LEDs aren’t designed to operate at high temperatures and they will overheat if 100 are put together like that.
I’d hope they’d at least use a full wave rectifier so they don’t flicker horribly.
Not being able to use a standard dimmer may be a show stopper for me. I paid over $1000 for my 20 something Insteon dimmers, so even if they make an Insteon dimmer compatable with LEDs I’m not about to run out and replace all of them. Unless the indicator LEDs on the dimmers themselves fail which has happened to people as they’re white ones. If in experamentingI damage the LED bulb or it just doesn’t work, fine, but I’m worried about the dimmer starting on fire or something if it has a load it doesn’t like.
There was no noticeable flickering even when moving my eyes with the lamps in sight, but it may be that they just connected half the diodes one way and the other half in reverse - meaning the unit as a whole would flicker at 100hz, which might not be easily observed.
I might dissect one of the devices to see exactly what’s in there.
I work with LEDs for a living. It’s obvious these lights have burned out.
Either you have to much Voltage running to them or they are overheating because you don’t have a proper heatsink.
Both of these could make your lights turn this “sickly” colour.