LED Lighting WPG estimate?

I've been working on an LED project and am very impressed with the PAR output so far. My first unit is a 48w LED fixture to replace the standard hood of a 12g nanocube deluxe. The PAR reading at the substrate level, approximately 12" from the light fixture, is 100 micromols compared 35 of the stock hood (2x24w CFs). PAR measurement was done with the Apogee meter set to sunlight. The LEDs used are 10 cool white and 6 royal blue Luxeon IIIs, this is a nanoreef tank.

The 16 LEDs are packed relatively close together in a small gutted 12" Current USA fixture.

I'm working on a larger unit and will be using lenses like in the Solaris units to see if they improve performance at all.

 

Which LEDs are you using, Cree or Luxeon? When you say they are 3 watt LEDs, does that mean you are running them at 3 watts - 4.2 volts and 700 mAmps? I know the Cree "3 watt" LEDs are normally run at only 700mA, and the voltage drop on them at that current is about 3.1 volts, or about 2 watts, not 3 watts.

 

I'm using the Luxeon IIIs running at 5 volts and 1Amp.

 

Are you sure they are running at 5V/1000ma? What is the ma that the driver controls them at?

Datasheets are usually a little optimstic and even the Lumileds one lists the max Voltage as 4.47 @ 700ma!!! and they state the typical V at 1000ma is 3.9 (page 6):

http://www.philipslumileds.com/pdfs/DS46.PDF

AC

 

Sorry, electronics isn't my strong point. The setup is using resistors instead of a driver. I had a friend test it and he said the LED volt and mAmp is 3.9 and 900 respectively.

 

syou should be using current controllers/drivers with high power LEDs and not resistors!!! You will end up frying the lot if one goes!!!

AC

 

Circuits for using High Power LED's is a good place to find ways to limit the current in LEDs. I made a current limiter using the two transistor (one FET) method. I haven't tried it out yet, so I can't say for sure that it works.

 

put the pics on a host (free ones are like imageshack or photobucket.)

Then past the url of the pic here enclosed by tags

example:

[ IMG ]http://photobucket/your account/yourphoto.jpg[ /IMG ] (don't put the spaces in these tags. I put them there just so that the site didn't think it was a picture :lol:

or click the icon above where you type for your posts of the mountain and sun and then paste in the Url there (this just adds the [IMG] tags for you )

Ac

 

Thanks everyone, the link looks especially helpful.

 

There is a surplus metals store near me called Blue Collar Supply, where I can buy several different shapes and sizes of aluminum extrusions, as well as odd sized sheets of various thickness of aluminum. The 8 foot by 3 inch channel cost about $27. I'm not convinced that an optimum heatsink is needed for the LEDs with the spacing typical for a planted tank light, so I expect the channel to work just fine.