I picked up some dirt cheap PLCC-6 RGB LEDs from ebay a while back, the usual sort you get from ebay with no datasheet or manufacturer to speak of. I started playing with some of them in a small LED matrix for a project, and the first thing I wanted to do was figure out how to mix the colors to get something close to white. I quickly found out that the red was severely unbalanced with the green and blue, to the point where I have to give it around 10 times more current to get decent color mixing, and it's not just a single shoddy LED...the whole batch was like that.
I broke out a light meter I happened to have lying around, and the balance in luminous intensity when driving all 3 colors at the same intensity is, in order RGB, 1 to 11 to 14. I know it's not just my shoddy light meter either, cause when I adjust the current based on a theoretical 3:6:1 luminous intensity ratio to get white it's actually white, but that requires driving red with 20 mA, green with 3.2 mA, and blue with around .4mA.
Now, obviously, buying cheap LEDs on ebay is less than optimal, sure. I'm just curious if anybody else has had similar experiences with these things? I expected them to have uneven brightness and not last a terribly long time, but I wasn't expecting such ridiculously unbalanced intensity.