the number come from the cree data sheet for a 3070 bin Z2 at 1400ma at 50C. they claim 6208 lumens. times 4 diode and divided by 4 1/2 sq ft grow area. I have not tested diodes from that bin but assume that the data from cree is accurate. I did test radiometric efficiency on a CD bin diode using a standard thermal test and the results agreed with the data from cree.
Ah, Z2 bin. Does Cree use that bin outside of 90CRI CXB3070s?
using a heatsink with know thermal coefficient measure temperature with IF thermometer. connect drive and power up diode. measure input voltage and current with DMM to determine input power, run for 20 minutes to allow system to reach thermal parody divide change in temperature by heat sink TC to determine amount of input power being converted to heat.the remaining input power is being converted to light and dividing this remaining power by total input power provides radiant efficiency. if 50 watts of input power produces 30 watts of heat then 20 watts is being converted to light for an efficiency of 40%. cree does use that bin for 80cri diodes as well. " theory is a good starting point but it rarely works in the real world without a lot of tweaking"
Thank you, this is a great answer. How are you getting an accurate thermal coefficient? Doesn't the heatsink temperature vary depending on where you measure? What about the thermometer, do you have accurate emissivity numbers for your heatsink? My IF thermometer is crap at absolute temperature, but the rise measured from ambient might be accurate enough.
50 watt precision resistors are design to be mounted to heat sinks and convert all of their input power to heat. I used one to calibrate my heatsink. temperature stays pretty constant across the heatsink with natural convection cooling after the system reaches stable operating temperature.with a good IF thermometer it is a good cheap way of finding actual efficiency of the unit your actually using. a cheap and dirty " ye ol engineers trick" I used a 3000k 80cri AB bin diode for the actual test and found the efficiency to be close to Crees data based on an LER of 328. this diode shows an actual efficiency of 38% at 1400ma.but performance in a comparison grow using super silver haze was disappointing. Z2 is the old listing for AB bin.I avoid high CRI diode because their output is a little lower than 70 or 80 CRI diodes.
at that price point your looking at very cheap chinese LEDs. you will be disappointed with your results using those "mars hydro" knock-offs. your yield will depend on your skills as a grower but you would get much better results with an HPS/MH combo. there is a reason that the price on those cheap leds are in free fall.they do not work very well or last very long.the 0.83 GPW your looking for can only be achieved by a skilled grower. you sound like a new grower with a lot to learn.it will take time to gain the knowledge and skills. you need be patient. no technology can replace education and hard work.
no way those pull like 80w so that would be an insane GPW
bro you just rhymed xDD
higher powered lights will give you more lumens per watt.a single 600 will give you more light than 2 300s
thx bro <3
i'm german and Irish. too stubborn to give up hehehehe
hahaha
I'm in Australia, can't seem to find the cxb3590 on any online shops.
