Ok, so you know those 1, 3 (and occasionally 5 watt LEDs), they look like this...
![](http://sparks.gogo.co.nz/.tmp/photoserver/full/270x250/exact-size/short-side-scaled/padded/270x250/fff/308417029.jpg)
So, I have played with the 1 watt variety for a while, they are freaking bright, work well as long as you heatsink them decently.
Anyway I thought I might as well get some 3 watt in my next order from China since I have some space to make up and a lack of ideas for new coolness at the moment.
But, there's something fishy, not just with one vendor, with pretty much all of them, the specs for the 1 watt leds are as you'd expect, about 3 something volts and 300 something mA, that gives you a watt right, no problem.
But the 3 watt ones, all the ones I've seen, have the same 3 something Volts (so dies in parallel obviously), but are rated at only 600 something mA, 750 at the top (so probably ou can say they are all around 650 mA in reality). According to my maths, that makes for 2 watts.
The lumen rated output seems to only be about double that of the 1 watt versions also, not 3 times.
In fact if you look closely at a lot of the photos you can see what appear to be two pairs of bond wires, clearly for 2 of the 1 watt die.
Am I missing something here, about luminosity or some funny led business.... or is this just a case of "China-math"?
A few examples from alibaba...
http://www.alibaba.com/product-detail/3-watt-led-high-power-led_1511033816.html?s=p 700mA
http://www.alibaba.com/product-detail/high-power-3-watt-led-chip_812470173.html?s=p 700mA
http://www.alibaba.com/product-detail/High-quality-750mA-high-power-white_1619987056.html?s=p 750mA (you can see the 2 pairs of bond wires clearly)
http://www.alibaba.com/product-detail/High-Efficiency-Cool-White-3-Watt_1715612471.html?s=p 550mA (!)
http://www.alibaba.com/product-detail/660nm-3w-led-1w-3-watt_1645633652.html 700mA
eBay the same.
Taobao is the same.
I have yet to see an actual 3 watt led in this package.