which is why they require huge heatsinks?
it isn't that much heat but they are far more heat sensitive. aka heat = death
Yeah. Unfortunately, LEDs aren't terribly efficient light-producers either. They're so much better than incandescent simply because incandescent sucks so much as a light source. It's like paying $1000 for some top-notch hookers and blow, but all you get is a well-done photograph of the hooker and a bag of PopRocks.
Philips' "LED Lighting Explained" document cites US DOE data which says that white LEDs are only about 15-25% efficient, compared to 8% for incandescent, and 21% for fluorescent, in terms of visible light generated versus energy input.
LEDs convert the waste into heat through internal resistance and internal reflections and subsequent absorption. (The materials that many LEDs are made of tend to have a very refractive index, so the light has a tough time leaving the die.
Incandescent generates heat through resistance as well, but a lot of it is lost as infrared radiation. (So the other solution would be to genetically modify ourselves so that our eyes could use this part of the spectrum.
)
Incandescent doesn't care if the filament runs at a few thousand degrees.
LEDs don't like it when the die temperature exceeds 135°C, and 85°C or less is generally preferred, as higher temperatures result in faster output degredation.
</brain dump>
bad batch or some really dirty power. i've had good luck with most any cheap bulb i've had, I mostly use those in the garage but the mix of bulbs continues to work for years. lights of america and other second tier brands. 75%? If you mean you have a dimmer, you can't use cfl with dimmer unless it explicitly supports it.
This is one of my biggest worries about the adoption of LED lighting. The expectation is 50,000hrs or more.
This includes the power supply. A cheap power supply is a way to save money on a fixture, which includes leaving out filtering and spike handling, as well as reduced efficiency.
The Department of Energy is doing testing commercially-available lamps and fixtures. Some of them are indeed quite efficient, delivering good light output and low power consumption. Some of them are as bad as incandescent in terms of lumens/watt. Sure, you can make a cheap power supply out of a bridge rectifier, two capacitors, and a linear regulator - or in a pinch, a poly-film capacitor. You might also consume 50W in order to power a 3W load. But a consumer without a watt meter probably wouldn't notice, perhaps with the exception of a power supply that gets hot enough to boil water.
Cheap power supplies will almost invariably have a low power factor. Put it this way, if you have a power factor of 0.5, you're yelling and screaming for the power company to deliver 10 units of power to you. They rush out 10 units of power, ring the doorbell and wait, but then you have to be a dick and only take 5 of them, and slam the door. Repeat this 60x a second.
Where's the downside? The power company has to send that energy over power lines, which incur losses. So a bit of those 10 units gets converted to heat before it can ever get a chance to do anything useful. If your power factor was better, such as it is with a circuit that's entirely resistive, or at least
acts like a resistor, then you might only be asking for 5.1 units of power. Then the power lines will only dissipate x% of those 5.1 units, instead of x% of 10.
But, this power factor correction doesn't
directly benefit a consumer. In theory, it means that the power company wastes less power and capacity, and doesn't need so much filtering to keep the line voltage all sparkly clean. Then, they can allegedly pass on the savings to.....someone.
On the subject of CFLs: I'm still running Litetronics Neolite CFLs here. They have a much better survival rate than generic stuff from Walmart/HomeDepot/Whatever. The one in my bathroom has to be more than 2 years old, and it's probably power-cycled at least 5x a day. (I do have incandescents over the sink though, and will use them if I just need to walk in to quickly retrieve something from the closet.)
They are available in the 2700K color temperature, which makes them look very much like regular incandescent bulbs. ~80 CRI, too.
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