DIY LEDs - The write-up - (split again)

[TheFishMan65]

This thread has been split due to performance issues. The previous pages can be found at:

http://reefcentral.com/forums/showthread.php?t=1678127

--beerguy

Wavelength: 470nm
DC Forward Voltage (VF): 3.2-3.8V DC
DC Forward Current (IF): 700mA MAX
Viewing Angle: 120 Degree
Intensity Luminous (Iv): 180LM

Well IMHO 470 nm should not be rated in lumens since it is pretty close to blue. But let's give this a shot.
180 lumens (assume this is the max) at 3.8 volts (max) and .700 amps (max) = 67.67 lumens per watt (best guess I can do to get efficiency, if you have better numbers adjust).
Now a CREE XP-G is rated at 3.2 volts at .700 amps (chart at the top of page 3). Lumens are 260 at the (chart at the top of page 2). So 260 / (3.2 * .7) = 116.07 lumens per watt. So they are roughly 116 / 67 or 75 % more efficient.

So roughly 4 CREE to 7 of yours to get the same amount of light. CREE are about $4.50 each or $18 for 4. Yours are a third the cost so $1.50 but you need 7. So 10.50 in LEDs. So how long does it take to make up $7.50?

4 Cree * 3.2 * .7 = 9.96 watts
7 China * 3.8 * .7 = 18.62 watts so you save 8.96 watts each hour
$7.50 / 0.07 = 107,000 kilowatts so in 107kw / 8.96 watts you break even. Roughly 12,000 hours. 12 hours a day roughly 1000 days at 365 days a year or about 2.75 years.

I did not double check my math

 

[TheFishMan65]

Also note that you have cheap electricity. I think the national average is $0.12 which would place the pay back closer to 1.6 years.

 

[kcress]

Wish that was MY average! 25.6 cents... &$^$#*@

 

[TheFishMan65]

Wow, someone in my local forum just found this article that links to the average for all the states. Your in luck kcress, Hawaii's average is higher than yours

 

[firechild]

This thread has been split due to performance issues. The previous pages can be found at:

http://reefcentral.com/forums/showthread.php?t=1678127

--beerguy




Well IMHO 470 nm should not be rated in lumens since it is pretty close to blue. But let's give this a shot.
180 lumens (assume this is the max) at 3.8 volts (max) and .700 amps (max) = 67.67 lumens per watt (best guess I can do to get efficiency, if you have better numbers adjust).
Now a CREE XP-G is rated at 3.2 volts at .700 amps (chart at the top of page 3). Lumens are 260 at the (chart at the top of page 2). So 260 / (3.2 * .7) = 116.07 lumens per watt. So they are roughly 116 / 67 or 75 % more efficient.

So roughly 4 CREE to 7 of yours to get the same amount of light. CREE are about $4.50 each or $18 for 4. Yours are a third the cost so $1.50 but you need 7. So 10.50 in LEDs. So how long does it take to make up $7.50?

4 Cree * 3.2 * .7 = 9.96 watts
7 China * 3.8 * .7 = 18.62 watts so you save 8.96 watts each hour
$7.50 / 0.07 = 107,000 kilowatts so in 107kw / 8.96 watts you break even. Roughly 12,000 hours. 12 hours a day roughly 1000 days at 365 days a year or about 2.75 years.

I did not double check my math

Comparing luminous flux of emitters with vastly different outputs is fairly useless. A red or blue emitter may have higher efficiency than a white emitter but it is almost guaranteed that the white emitter will have a much higher rating in lumens/W. This is because lumens are a measure weighted towards the more visible part of the spectrum (yellow and green) and therefore a light source that is short in this part of the spectrum will have a luminous flux.

As a comparison, Cree XP-E blue (not royal blue) are rated at up to 30 lumens @30mA.

 

[TheFishMan65]

Fire child that is why I said:

Well IMHO 470 nm should not be rated in lumens since it is pretty close to blue.

Unless I can radiant flux values for the China version this is the best I can do. This just another reason to be wary of some of the cheap knock offs. If they rate them wrong there is really no way to compare them.

 

[firechild]

Absolutely. It is possible for a 470nm emitter to have a higher luminous flux than a Cree 470nm emitter while still having a lower efficiancy. If the cheap emitter has a much wider overall output but still a 470nm peak it will skew the results.

 

[kcress]

Wow, someone in my local forum just found this article that links to the average for all the states. Your in luck kcress, Hawaii's average is higher than yours

OhhHHHHHhhh Lucky me..

 

[S&KGray]

Wow, someone in my local forum just found this article that links to the average for all the states. Your in luck kcress, Hawaii's average is higher than yours

OhhHHHHHhhh Lucky me..

Haha yeah, I just looked at my electric company's website for the residential rates effective Nov 1, 2011.

Drum roll please.....

$0.40380 per kWh

So how fast would my payback be? (If I can ever get my XP-G's up over a tank, lol)

 

[kcress]

Man that is oppressive!

Your payback would be about 3 hours I think.

 

[TheFishMan65]

I guess I shouldn't complain much about mt $0.1250 or so.

 

[ghellin]

Wow I only pay $.095 in Edmond, ok

 

[brassmonkyballs]

Haha yeah, I just looked at my electric company's website for the residential rates effective Nov 1, 2011.

Drum roll please.....

$0.40380 per kWh

So how fast would my payback be? (If I can ever get my XP-G's up over a tank, lol)

holy cow batman! 40 cents? really? geez. I'd be sitting in the dark in my underwear only powering my refrigerator (beer) and my reef tank...of course I would obviously be divorced at that point too..........:beachbum:

 

[Snootch]

Haha yeah, I just looked at my electric company's website for the residential rates effective Nov 1, 2011.

Drum roll please.....

$0.40380 per kWh

So how fast would my payback be? (If I can ever get my XP-G's up over a tank, lol)

Holy smokes, $0.40380 per kWh !
That would translate to over $500 monthly electric bill considering my usage.
I'm getting charged $0.086 for the first 1000 kWh and $0.108 over 1000 kWh down here in South West Florida.

KC

 

[S2minute]

Fixture update

Fixture update

Here's an update to a project i've been working on. I've been reffering to JPs build and pics for help,(very helpful btw). All tests passed except the short test. I had 7 leds short to a screw which i fixed. 144 LEDS: 18 XM-L(9 T3 WW, 9 T6 CW)@ 1500 MA, 24 XP-G,(12 NW, 12 CW), 102 XP-E RB. Thanks for all this info guys. I'm a noob at this and this project has been a long time commen.

 

[kcress]

THAT is CRAZY!

Pretty cool rig you have there.

 

[ghellin]

That looks great!

 

[007Bond]

S2--Neat concept, have not seen a set up like yours, with the stand offs of the leds. Your led's should keep real cool with that design. What is your intent with the stand offs? the ability to aim all the leds in directions you want? also why the bend in your frame? Keep posting your build, looking forward to your progress. Bond

 

[S2minute]

Light Fixture

Light Fixture

Thanks ...i still have a long way to go, 40 & 60 degree lenses and maybe 80s for the XM-Ls but, it's only going to be about 10" from the surface so i don't know how those degree lenses will effect. Plus, it's a series rig since i'm using Fishmans Cats. I'm taking it wicked slow so i don't mess up. So far it has involved a TON of fabrication :hammer: but, with the effort i'll be able to direct each LED on it's own HS in pretty much ANY direction i need to. I intended the bend in the frame so as to further enhance the effect of sunrise/sunset and help cut down on the shade areas like under the tank frame braces. Each section has 8 strings of 6 LEDS though there are only 7 mounting bars. The 8th string are XM-Ls and staggered, in the center of the frame, all 3 strings running the length of the fixture. SO, i can use a controller to sim sunrise/sunset with 1 bar dimming up at a time, then for a period around noon, dim up the 3 strings of XM-Ls There will still be lots of shade as the live rock itself is on an elevated platform.

 

[007Bond]

S2 Sounds real cool! I'm sure the thought, time, and effort will be rewarding for you in the end. Looking forward for your build updates. Bond