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I recently started designing a pcb for flashing lights I want to use in a pavillon at festivals, garden parties and the like.

Now my question is, can anyone tell me which kind of LED that has the most lumens/watt?

  • 5mm clear LED's
  • Clear surfacemount PLCC LED's
  • 1 or 3 W LED's

I've previously experimented using 12-15 5mm which turned out pretty good as a "mini" spotlights, but I have no experience using highpowered LED's.

I want to build the poormans buck as supply on the back of the PCB, so I thought the surfacemount LED's would be the best, but only if they perform "okay" in terms of lm/W.

Note: They will be powered from the same large 12V batteries that runs the music.

--- EDIT ---

Yeah, I should definately have given more details. Im looking to make dance-lights in RGB colors as well as white for a strobe and perhaps UV. Number of channels doesn't matter too much, as long as I have at least one for R, G and B.

I AM on a budget, but not too tight either. My original plan was to have 4-6 PCB's with 50-ish LED's each (enough to make a lot of light in the dark), which is why I preferred 3-cent LED's over 50-cent ones.

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    \$\begingroup\$ I have 'substantial experience' in LED lighting design. I could spend significant time answering and probably give you a useful answer BUT the tighter you can define what you want the briefer and better any answers can be. Your question + comments give a fair idea of what you want - but mention of chinese ebay suppliers and 3 cent parts hints at budget limitations that may matter. You talk about 5mm LEDs and 3 Watt LEDs & 'PLCC' LEDs. Quite how each relate is uncertain. How many buck converters and/or how many independent modules do you need? Poorman's cct is OKish but its time is past. ... \$\endgroup\$
    – Russell McMahon ♦
    Jul 13, 2014 at 16:53
  • \$\begingroup\$ ... Cree make amongst the most efficient LEDs available. Chinese junk LEDs have a good chance of being junk. Lumen maintenance (brightness retention over time) will often by abysmal. How much efficiency is enough - and why? If you get 2 x light per Watt but say 6x price is that acceptable? ie how much does energy used matter? |Cree XB-D can be very well priced and are reasonably efficient. XR-E are higher powered but much higher cost. Nichia make some nice SMDSs at lower power at over 150 l/W (lumen/Watt) at 10 to 20c. |... \$\endgroup\$
    – Russell McMahon ♦
    Jul 13, 2014 at 16:59
  • \$\begingroup\$ Cree XB-D Digikey \$\endgroup\$
    – Russell McMahon ♦
    Jul 13, 2014 at 17:00

1 Answer 1

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Most lumens per watt is a moving target. It's even more of a moving target if you care what they cost. As such, browse your supplier's website/catalog and enter

  1. power
  2. lumens
  3. cost if you care about cost

into a spreadsheet, if, as is too often the case, they don't have a handy sorting tool that will list the results in lumens-per-watt directly. Make a formula for lumens/watts, and a formula including the cost if you care about cost, and see what you get. In 6 months, it will all be different.

As for the types you list, I'm pretty sure none of them are even in the running for that competition.

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  • \$\begingroup\$ Cost is also a factor in this puzzle - the options I mentioned is of course not the only ones to choose from, but those are the cheap versions I've found. My supplier is chinese resellers on Ebay, so I don't trust too much whatever they write on their spec sheets, and hence I was looking for a more general answer that "usually X is better than Y" \$\endgroup\$
    – Tagger
    Jul 13, 2014 at 15:33
  • \$\begingroup\$ Some things are worth purchasing from reputable suppliers. I assume that all "Chinese reseller on ebay" LEDs are factory rejects that do not perform to specs. Except perhaps the ones that are a low-output LED packaged to look like an expensive high-output LED, so you'll assume that they are "factory reject Cree's at a bargain price" when they are actually just something that looks more or less similar in a picture... \$\endgroup\$
    – Ecnerwal
    Jul 13, 2014 at 15:45
  • \$\begingroup\$ Yeah I guess you get what you pay for :-) The idea is to build them at a very low cost, so I don't mind using factory rejects and manually testing them first. For the SMT ones mentioned I would need around 500, which is 50-80 cents each LED at a danish quality distributor or 3 cents on ebay \$\endgroup\$
    – Tagger
    Jul 13, 2014 at 15:52
  • \$\begingroup\$ Now you mentioned Cree's, do you think those would be in the "running for the competition"? \$\endgroup\$
    – Tagger
    Jul 13, 2014 at 15:54
  • \$\begingroup\$ They (and several other companies) are actively chasing the most-lumens-per-watt goal, and they have at times been in the lead, so yes. And consider the savings of not having to assemble 499 LEDs when you contemplate one that will do the job of 500 "cheaper" ones. \$\endgroup\$
    – Ecnerwal
    Jul 13, 2014 at 16:11

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