Cree CXA analysis

SupraSPL · Dec 9, 2013

MrFlux said:
It's 3.7 degrees total; This is the temperature difference between the back of the Vero and the face of the heatsink. The equation used is not so scary at all, it's called Fourier's law.

Thanks I will get up to speed on this so I can get an idea of COB junction temps. I need to be able to estimate the Tj so I can compare the efficiency and determine whether itd be best to stick with XML or go to Vero18 or Vero29 and how hard to run them.

MrFlux · Dec 10, 2013

For COBs the specs tend to use the case temperature Tc (measured at the back of the heatspreader) instead of the junction temperature Tj. There is no need anymore to estimate the Tj or even to know the junction to case thermal resistance.

SupraSPL · Dec 10, 2013

I need it to calculate for temp droop. This is for the Vero29

coolbreez1 · Dec 22, 2013

Does anyone know how to do the conversion from lums to umol?

Even better a graph that displays the relative flux of the viro18 series in umol.

MrFlux · Dec 23, 2013

coolbreez1 said:
Does anyone know how to do the conversion from lums to umol?

Even better a graph that displays the relative flux of the viro18 series in umol.

Going from lumens to umols is not so simple, it is explained in the first few pages of this thread. If you have any specific questions let me know.

The umols per Watt for the Vero family, at test current and 25C:

[TABLE="class: outer_border, width: 400, align: left"]
[TR]
[TD]Emitter[/TD]
[TD]umol/s/W[/TD]
[/TR]
[TR]
[TD]Decor[/TD]
[TD]1.4[/TD]
[/TR]
[TR]
[TD]3000K[/TD]
[TD]1.76[/TD]
[/TR]
[TR]
[TD]4000K[/TD]
[TD]1.78[/TD]
[/TR]
[TR]
[TD]5000K[/TD]
[TD]1.83[/TD]
[/TR]
[/TABLE]
So the normal CRI emitters have more or less the same number of photons going out. The high CRI Decor emitter has substantially less. It can be viewed as a regular 3000K emitter with a filter over it that blocks some of the green light (the filter would look a bit pinkish). For a grow light any photon is a good photon so filtering the light makes no sense.

I am exaggerating here a bit that high CRI is a normal emitter with a filter to get the point across of how many photons are lost.

happy75 · May 10, 2014

MrFlux said:
It's a real shame that there are no 2700K spectra available. Was expecting this to be a Coke vs Pepsi test but that was fortunately not the case.

This is a very interesting thread..unfortenately it stopped. I wonder...did you found a 2700k specra of the Vero?

SupraSPL · May 10, 2014

We did get the LER for the 2700K CXA, it is 321 according to Cree (325 for the 3000K). Now the mid bin 2700K CXA3590 is available from digikey and mouser.

happy75 · May 10, 2014

SupraSPL said:
We did get the LER for the 2700K CXA, it is 321 according to Cree (325 for the 3000K). Now the mid bin 2700K CXA3590 is available from digikey and mouser.

Last week I received spectrographs of the Vero 18, 2700K 90 vs 2700K 80 cri and the Vero 18 3000K 80 cri vs 2700K 80 cri. The last one is posted as an image, for those who are interested.

MrFlux · May 10, 2014

SupraSPL said:
We did get the LER for the 2700K CXA, it is 321 according to Cree (325 for the 3000K). Now the mid bin 2700K CXA3590 is available from digikey and mouser.

I didn't even know Cree gave out the LER... you happen to know where in Cree's documentation labyrinth this can be found?

happy75 said:
Last week I received spectrographs of the Vero 18, 2700K 90 vs 2700K 80 cri and the Vero 18 3000K 80 cri vs 2700K 80 cri. The last one is posted as an image, for those who are interested.

Thanks for the spectrographs. The 3000K curve differs significantly from what's in the specs though. In your data the blue peak is at 60% of the red peak, in the specs it is at about 40%.

So are you sure the measurements are accurate. It's very easy to get ambient light contamination, or spurious reflection from say a colored (blue?) wall.

happy75 · May 10, 2014

@MR FLuX. I don't know if they are accurate. A sales manager of bridgelux made these at my request.

MrFlux · May 10, 2014

happy75 said:
@MR FLuX. I don't know if they are accurate. A sales manager of bridgelux made these at my request.

Cool. But strange how his spectra get to be so different.

happy75 · May 10, 2014

MrFlux said:
Cool. But strange how his spectra get to be so different.

Yes, I do not have much experience with this, but logic tells me that it should not be so different. Maybe it is best to measure the Vero's and the cree's 2700-3000 on the same manner, and on the same machine so we can compare them better. Maybe bridgelux or cree aren't that honest in their brochures. Or maybe there is another simple explanation for this.

SupraSPL · May 10, 2014

Hmm also seems strange that the 2700K has more output than the 3000. Maybe different bins?

Regarding Cree CXA LER, I contacted them specifically about the LER for 2700K and surprisingly they provided it along with the 3000K. It agrees very well with your number. Now we can make a comparison between the CXA3590 2700K and the CXA3070 3000K.

stardustsailor · May 10, 2014

SupraSPL said:
Hmm also seems strange that the 2700K has more output than the 3000. Maybe different bins?

Regarding Cree CXA LER, I contacted them specifically about the LER for 2700K and surprisingly they provided it along with the 3000K.

I'm pretty interested for some radiometric info about the CXA3070-0000-000N00Z227H/F...
I agree 100% with what you've claimed ,regarding the ability of Cannabis to use ,
almost equally efficiently, most of the 'PAR ' range ...
But also I agree half part ...
We 've not to neglect the photomorphogenic effects of light .
Alteration to circadian rythms /metabolism /assimilation /etc are aided/enhanced /manipulated
by certain wls ..
Anyway,I've already experimented with those 2700 K spectrums...
No matter how much you provide during flowering ,the swelling buds want even more ...

I've my eyes on that 2700 K 3070 ,some time now ...

Thanx ..
Cheers .
:peace:

SupraSPL · May 10, 2014

I am on board with that, once we have to photon count where we want it, photomorphogenic comes next. The 2700K spectrum may have an advantage in the red zone and the 3000K may have an advantage in the blue zone. So, Id say the CXA3070 2700K Z2 is approximately as good as the CXA3070 3000K Z4. Unfortunately the CXA2700K Z2 is not available to us yet. Here is how the top bins compare.

CXA3070 2700K vs CXA3070 3000K top bins.png

Chronikool · May 11, 2014

Supra...do you have the numbers of the 3050 W2 (mid bin) 2700k?

Bueno Time · May 11, 2014

Chronikool said:
Supra...do you have the numbers of the 3050 W2 (mid bin) 2700k?

I had saved a copy of one Supra posted some time back.

SupraSPL · May 11, 2014

Good call bueno time. It looks like that was before I had the 2700K LER from CREE, here are the updated numbers with 321 LER

stardustsailor · May 11, 2014

At 1.8A ,having 90.92 lm /Watt and with that kind of relative power spectral distribution of a typical 2700°K temperature ,can not be easily characterized as a 'weak' led ...

(Still I'll wait for the Z2 bins to hit the market ....

...)

SupraSPL · May 11, 2014

Yea Im sure it would grow some bud :joint:

. From the 2700K we currently have to choose from, each has their ups and downs. Got to throw the 3000K Vero in there since it is 8% blue.

CXA3050 2700K W2 vs CXA3590 2700K AD vs Vero 29.png

Cree CXA analysis

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