0.5W LEDs on ebay

[ecotack]

I have a good selection of LEDs from 3mm to superflux and my recent buy LXML-PWC1-0080 Luxeon Rebels.  Two of the rebels at 600 mA (12v battery using an LM317 to limit current) in a floodlight appear to be brighter then a 20W 12v halogen, based on my lights I have at our horses field.

I came across some 0.5w 5 chip LEDs on ebay, rated at 45000 MCD.  A converter I used put them at about the same LUX as the Rebels, which I doubt.

I was wondering if anyone had used these 0.5W (100mA) LEDs and could comment on the output as compared to a standard 30mA superflux?

With the TO-92 and surface mount LM317s having a 100mA rating, I was thinking I could make some neat 12V LED bulbs.

Out of interest, I found the simplest way of mounting the Luxeon Rebels is to solder a solder tag to the thermal pad, then two flexible wires re-enforced by a blob of epoxy.  Using inflexible wire without the epoxy just pulled off the surface mount tracks.

[justDIY]

Welcome to the forums!

While it is mathematically possible to convert almost any unit of measurement to any other unit, it's not often practical.

mcd = millicandela

there is no practical means to convert candela to lumens.  Rob has a wizard in the led center that takes a crack at it, but is often wrong - a large grain of salt is needed when reading the results.

any led whose output is measured in candela is an "indicator grade" led, and cannot be compared to "illumination grade" leds whose output is typical measured in 10s or 100s of lumens.

[BVnursery]

The 5mm, 100ma leds are a pretty new item on ebay.  If we are looking at similar listings the seller is pretty new to ebay too.

[Rob]

Rob has a wizard in the led center that takes a crack at it, but is often wrong - a large grain of salt is needed when reading the results.

   I'd prefer to say the lumen wizard "makes assumptions that may not align to the way specifications are generated."

The seller wants the biggest luminous intensity number he can obtain, and so measures the brightest spot in the beam and lists that number on the spec. The calc assumes the number you provide for conversion is representative of the average (not peak) luminous intensity of the beam. For narrow beams widths, that's not a terrible assumption. For wider ones it gets problematic. That's when you get your salt out.

No standards exist for measuring luminous intensity, so we're in a tough spot.

[minster9]

  I've found that .010" bus wire to work the best for lead wires on the rebels. I flatten the wire ends first with a hammer & then tin the ends w/solder. I always tin all 3 pads on the rebel,too. I agree with Ecotack,embedding the electrical end of the rebel after attaching leads in epoxy is pretty much a necessity. Never had much luck w/stranded wire. I always embed the lens end too after soldering to whatever you use,leaving only the lens exposed. Same reason as for the leads,to preveny delamination.