LED chip real-world comparison?

[MEXICOWANDERER]

Off-brand. CREE. Bridgelux. Anyone out there have real-world experience with head-to-head comparison of the three? Why do the name brand chips cost 400-500% more? Performance? Longevity?

Thanks

[landyacht318]

While there are obviously a few here with knowledge of the type you seek Mex,

I think perhaps you would find a wider knowledge base to pull from over on the candlepower forums.

http://www.candlepowerforums.com/vb/forum.php

Lots of 'build your own' types over there, from machining the housings to building the drivers.

[MEXICOWANDERER]

Thank you.

One generic white 5K chip on eBay, $1.40. One Bridgelux same 10 watts $4.40 or more.

When it came time to purchase amber tow truck chips and red ambulance chips I went with Bridgelux. On a hunch I decided that a colored chip shining through a transparent lens would permit more lumen to pass through the lens. With a colored lens it seems to absorb a lot of the brightness emitted by a white chip.

[GordonThree]

Where are you getting the 400-500% figure from?

In my experience the biggest cost of name brand LEDs is binning. Even with Cree and Philips both claiming freedom from binning, it's still something you have to do and it costs $$$$.

When the name brand guys make LEDs, on a huge silicon wafers, a machine tests each LED on every wafer and assigns it a bin, based on power output and color accuracy. In the world of white leds, these young ones are still blue. The blue leds go off on an adventure to get their phosphor coating, mated with a substrate and encapsulated. Then they get tested again, for lumens and color temperature, and assigned their final bin.

When you read a datasheet, you see there might be 3 or 4 (used to be like 10 for Cree) part numbers, for the same LED. Some list an exact / specific color temperature and an exact lumen output - so those will be the most expensive. If you're building a product were uniform appearance is important, you pay for those premium LEDs. Other part numbers list a color temperature range or a lumen output range. These LEDs are close, but not perfect, so they're cheaper. Lastly, there'll be parts that list a color temperature range that is huge, like 5000-10000 kelvin or they list a "minimum" lumen output. These are the chips left over that don't fit in a premium bin.

I've noticed Philips and Cree both drastically downsized their unbinned offerings, my guess is they're selling chips that don't pass muster to generic brand dealers rather than put substandard chips through the expensive phosphor and encapsulation process.

The LEDs on fleaBay come from factories with very little quality control. They don't bother with anything but the most basic binning (cool white, warm white, etc). They don't bother with uniformity in terms of color or lumen output. If I wasn't so lazy I'd post pictures of ebay panels I've purchased that have a multitude of different shades of "white" on them.