milkyspit
Flashlight Enthusiast
jtr1962 said:Amazing results and thanks for testing these NewBie!
To show how much less heat these make for a given lumen output let's say the design goal is 80 lumens. You can get that with a typical Luxeon III running at 700 mA. Typical Vf is roughly 3.7 volts so input power would be 2.59 watts. Efficiency is about 10% so you would have to deal with about 2.33 watts of heat.
Now let's do the same thing with a Cree XR-E. You only need about 350 mA. Vf would be around 3.1 volts so power input would be only 1.085 watts, a reduction of 58% compared to using the Lux III. The heat reduction is even more impressive. Since this part is about 25% efficient you would only be dealing with about 0.81 watts of heat, a reduction of 65% compared to the Lux III. In other words, one-third the heat for the same lumen output. :rock:
The good times are just beginning. A few years ago I was waiting patiently until LEDs finally reached or bettered fluorescent tube efficiency. That time has finally arrived. I can hardly wait to see what Cree has in store for us next year!
Jtr, how does one know the efficiency of a given LED? You cited 10% for your LuxIII scenario.
On a semi-related note, I've been building with LuxI S**H for a while now and have noted that there's a VERY noticeable reduction in heat... for example, my M180 builds even after two hours of continuous runtime, generate only lukewarm amounts of heat. As far as light, we're looking (ballpark) at 180 lumens out of the emitters with efficiency around 55 lumens per watt. But how efficient in percentage terms are these emitters as far as light vs. heat? The evidence suggests there must be a marked increase beyond that 10% figure, but how do I quantify?
As far as fluorescents, good riddance! I've long been of a strong ANTI-fluorescent mindset, given that EVERY FLUORESCENT TUBE CONTAINS MERCURY VAPOR! Nasty, nasty, NASTY stuff! And even if the manufacturers don't gloss over this fact (most do), we all know broken fluorescent tubes are most definitely NOT cleaned up in the manner one would treat release of a hazardous chemical... in school classrooms full of children, for example, nobody leaves, the janitor shows up with his dustpan and just sweeps up the glass. Not good!
If high-efficiency LEDs can put the final stake through the heart of fluorescent lighting, then God bless them.