Led Users Unite!

[Spuzzum]

Well I'm no electrical engineer but electricity takes the path of least resistance so if you parallel wire an LED and Resistor the current goes through the path of least resistance (LED) unless it's burnt out in which case that circuit is then high resistance so it will go through the resistor which is necessary to stop the current increasing in the remaining LED's and causing cascading failure from running too high a current.

Am I missing something?

This is the way I understand it... in series, all led's in string share same current, but voltage is added for each. In parallel, all led's share same voltage, but current is added for each.

If say led's use 2.1v @ 350mA, and you have a 24vdc source @ 5 Amps. You can wire 11 led's in series for 23.1v, or 10 in series for 21v. But you still have 4v to "waste", and get down to 350mA...

Solution 0: 10 x 1 array uses 10 LEDs exactly
+----|>|----|>|----|>|----|>|----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 10 ohms

The wizard says: In solution 0:
each 10 ohm resistor dissipates 1225 mW
!! the wizard thinks the power dissipated in your resistors is a concern
together, all resistors dissipate 1225 mW
together, the diodes dissipate 7350 mW
total power dissipated by the array is 8575 mW
the array draws current of 350 mA from the source.

8575mW - 7350mW = 1225mW, or 1.225 Watts



Now, if wiring in parallel, you'd need a power source "exactly" 2.1v.. with a lot more amperage than 5 Amps.. unless you want a lot of drivers.

Say you have a 2.3v source, with 50 Amps..

50A / 350mA = 142.857 led's (142)


But, if using the same 10 led example as the series array....

Solution 0: 1 x 10 array uses 10 LEDs exactly
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms
+----|>|---/\/\/----+ R = 1 ohms

The wizard says: In solution 0:
each 1 ohm resistor dissipates 122.5 mW
the wizard thinks ¼W resistors are fine for your application
together, all resistors dissipate 1225 mW
together, the diodes dissipate 7350 mW
total power dissipated by the array is 8575 mW
the array draws current of 3500 mA from the source.

Yes, they're the same... but that's "if" the source is within 0.2v of the actual draw. Raise the source to 3v.. a more "commonly available" power adapter...

Solution 0: 1 x 10 array uses 10 LEDs exactly
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms
+----|>|---/\/\/----+ R = 2.7 ohms

The wizard says: In solution 0:
each 2.7 ohm resistor dissipates 330.75 mW
the wizard thinks 1W resistors are needed for your application
together, all resistors dissipate 3307.5 mW
together, the diodes dissipate 7350 mW
total power dissipated by the array is 10657.5 mW
the array draws current of 3500 mA from the source

10657.5mW - 7350mW = 3307.5mW, or 3.3075 Watts


3.3075 Watts - 1.225 Watts = 2.0825 Watts (~2.1w)

And that's at 10 led's.. adds up for an entire panel. And that's "if" the source is only 0.9v more than the draw.

Don't forget to factor in the power adapter's ac/dc loss as well.. smaller the adapter's output, less efficient the conversion. Seems that converting 110ac to 48vdc is MORE efficient than converting to 24vdc. And a supply with only 3vdc is even LESS efficient. .. Go figure, eh? Seems those dimmer switches we all had in our dining room chandeliers.. all they did was resist/waste the energy.. unless they were "switching regulators" that turned on and off as the power is needed. Otherwise, they're just a glorified resistor .

http://led.linear1.org/led.wiz



Cheers bud........

 

[budlover909]

dad says dont forget red and blue leds run at different voltages so running parallel mixed isnt gonna work as well youd have to run parallel reds and blues alone so for mixing diodes serial is better because you can add voltages and you don't use a resistor well you can but dad says its just better to use bypass diodes like whats in the 90w replacement i just got today

 

[surgedup]

hows it goin fellas have been gone for awhile but my blackstars are kickin ass phenomenal growth I will post some pictures soon !

 

[dunit]

dad says dont forget red and blue leds run at different voltages so running parallel mixed isnt gonna work as well youd have to run parallel reds and blues alone so for mixing diodes serial is better because you can add voltages and you don't use a resistor well you can but dad says its just better to use bypass diodes like whats in the 90w replacement i just got today

Most of the panels I've seen have multiple power supplies dedicated to red or blue to avoid mixing.

 

[dunit]

This is the way I understand it... in series, all led's in string share same current, but voltage is added for each. In parallel, all led's share same voltage, but current is added for each.
If say led's use 2.1v @ 350mA, and you have a 24vdc source @ 5 Amps. You can wire 11 led's in series for 23.1v, or 10 in series for 21v. But you still have 4v to "waste", and get down to 350mA...
8575mW - 7350mW = 1225mW, or 1.225 Watts

Now, if wiring in parallel, you'd need a power source "exactly" 2.1v.. with a lot more amperage than 5 Amps.. unless you want a lot of drivers.
Say you have a 2.3v source, with 50 Amps..
50A / 350mA = 142.857 led's (142)

But, if using the same 10 led example as the series array....

Yes, they're the same... but that's "if" the source is within 0.2v of the actual draw. Raise the source to 3v.. a more "commonly available" power adapter...

10657.5mW - 7350mW = 3307.5mW, or 3.3075 Watts

3.3075 Watts - 1.225 Watts = 2.0825 Watts (~2.1w)

And that's at 10 led's.. adds up for an entire panel. And that's "if" the source is only 0.9v more than the draw.

Don't forget to factor in the power adapter's ac/dc loss as well.. smaller the adapter's output, less efficient the conversion. Seems that converting 110ac to 48vdc is MORE efficient than converting to 24vdc. And a supply with only 3vdc is even LESS efficient. .. Go figure, eh? Seems those dimmer switches we all had in our dining room chandeliers.. all they did was resist/waste the energy.. unless they were "switching regulators" that turned on and off as the power is needed. Otherwise, they're just a glorified resistor .

Cheers bud........

So much for keeping it simple

I do get that ac to dc conversion, espeically to very low voltages isn't very efficient so the series thing doesn't make that much sense but I'm gonna guess that this isn't a new problem and has been addressed in electronics applications many years ago. Will have to do some digging and see what I can come up with.

 

[Spuzzum]

Here's something else to consider... blues usually have about 50% of the Lumens that reds have, so if a manufacturer uses an 8:1 ratio of red to blues, but the blues are only 1/2 the lumen rating as the reds.. and the manufacturer did his ratio by # of stars, not actual red Lumens to blue Lumens.. well, then the ratio of red to blue would actually be 16:1. .. That could be a major reason why some panels just don't cut it. That's also where a panel using "both" 1w and 3w led's is actually a "good" thing. Cree 1w XP-E reds @ 350mA have 45.7 - 62 Lumens.. depending which bin they're from, and always labeled as such.. so customer knows what they're getting. Blues have 30.6 - 39.8 Lumens at 350mA.. bin depending again. Cheap Chinese crap has even less. Set the 1w reds at 100 Lumens a piece, followed by 3w blues set at 100 Lumens a piece. Better for the ratio.

Then.. to find how many led's needed to replace a hid...

250w hps = 28,000 Lumens / min: 2.5' x 2.5', max: 3' x 3' - plants 2' maximum
400w hps = 50,000 Lumens / min: 3' x 3', max: 4' x 4'
600w hps = 90,000 Lumens / min: 4' x 4', max: 5' x 5'
1000w hps = 140,000 Lumens / min: 4' x 6', max: 5' x 7'

http://www.bghydro.com/BGH/items.asp?Cc=H2&iTpStatus=0&Tp=&Bc=

But remember.. the 250w hps actually uses 300w, and the 400/600/1000w's use more as well. So when calculating Lumens per area, and efficiency.. calculate using 300w hps @ 28,000 Lumens.

28,000 Lumens = 280 led's set at 100 Lumens each.

2.3v 620nm red/orange @ 600mA = 102.3Lm
2.2v 630nm red @ 500mA = 103.46Lm
3.5v 470nm blue @ 900mA = 104.04Lm


Or... keep the reds at "typical" 350mA, and the blues at "typical" 350mA, but add twice as many blues.. ie instead of 8:1 red to blue, use 4:1 red to blue. Led's are most efficient at "typical".. ie: 50%. They only double in lumens by 80% at maximum.. 20% loss.

620nm: 2.1v @ 350mA = 62.0Lm
630nm: 2.1v @ 350mA = 73.9Lm
470nm: 3.2v @ 350mA = 30.6Lm


There's also the PAR measurements.. actual "used" spectrums from those Lumens. Led's are pretty much all usable light, as it's personally selected by wavelength.. compared to a hid, where there's "wasted" light that's emitted in the wrong/unusable spectrums. .. What that percentage is, I have no idea.. that's where aiming for 75% of the hid you're replacing is a good rule to follow. Maybe that's why they say they replace a hid twice the size? Look at an hps spectrum graph, and at least 50% isn't usable by the plant.



Cheers...........

 

[devk]

Yo whats up guys I have a issue!
Do your guys fans inside your lights blow in or blow out of the light?
The one Iv seen blows in I don't think that's the best way to put it..What do you guys think ?

 

[kush groove]

Yo whats up guys I have a issue!
Do your guys fans inside your lights blow in or blow out of the light?
The one Iv seen blows in I don't think that's the best way to put it..What do you guys think ?

im running blackstar and it seems my fans air pulling air from the top and out the sides.............not sure which would be better though

 

[shovit]

They blow in.

If your heatsink is finned you can flip the fans and alutape the heatsink and force the air to pass it by before exiting, if you understand what im saying.

Some people even flipped the ventilation, intake at the top and exhaust at the bottom to heat up the growarea and cool the leds.

 

[devk]

Thats the right way right?

 

[Spuzzum]

Yep.. blowing in/down on the heatsink is best, even if just a cheap aluminum panel with "no" fins. Otherwise, there's no guarantee the cool air will be flowing across the panel.. it could be pulled directly from the side intake vents, and output from the fans.. but never actually hit the fins. Given a short housing for the panel though, that "may" not be too much of an issue. But pushing cool air is always better for the fans than pulling hot air, so that's something else to consider.. though at the rate the air's moving, and the low temps to begin with.. the air's not really that hot to worry about either.

Think of it as your cpu with a cooling tower, or even an older p1 with a 5mm fan. Blowing into the cooling tower will reduce temps by at least 5c more than pulling the air through. Same as the p1 heatsink.. fan blowing down will be cooler than fan pulling up.

 

[Homegrown4Life]

Hey guys!, im just starting out with my LED growlight and so far its been great. I have some pics if anyone wants to check out my new setup =D

 

[devk]

I disagree I would rather swap fans often then swap lights often... Hot air coming out the side will just head up and back into the light if the fans are just blowing the hotter air from the higher points in the room where hot air is usually accumulated...Not useful.....Even the heat cause buy the small DC fan is passing threw the light B4 exiting..I don't think this the best way...I dont know about you man but my cpu is always fucking hot

 

[meharmon]

The fans blow with enough force that recirculation should not be a concern. They could be upgraded further if desires though. Anything over ~30 CFM should be an improvement. You can get an 80mm that blows over 80 CFM but its kinda loud -- 56db (Vantec brand).

 

[brosmoke]

How's it going guys just purchased my first led. I ended up getting the blackstar 240w and was wondering how many mature plants this single light could handle thanks for the help

 

[budlover909]

Most of the panels I've seen have multiple power supplies dedicated to red or blue to avoid mixing.

tear that unit down to the bare board if the diodes are not in solid lines you are running mixed in fact 99.999999999% are going to be mixed diodes multiple power supplies are there to push different strings but the power supplie are all the same remember pics i posted earlier back yea aint not a single line of diodes hooked to those running single color

 

[budlover909]

Here's something else to consider... blues usually have about 50% of the Lumens that reds have, so if a manufacturer uses an 8:1 ratio of red to blues, but the blues are only 1/2 the lumen rating as the reds.. and the manufacturer did his ratio by # of stars, not actual red Lumens to blue Lumens.. well, then the ratio of red to blue would actually be 16:1. .. That could be a major reason why some panels just don't cut it. That's also where a panel using "both" 1w and 3w led's is actually a "good" thing. Cree 1w XP-E reds @ 350mA have 45.7 - 62 Lumens.. depending which bin they're from, and always labeled as such.. so customer knows what they're getting. Blues have 30.6 - 39.8 Lumens at 350mA.. bin depending again. Cheap Chinese crap has even less. Set the 1w reds at 100 Lumens a piece, followed by 3w blues set at 100 Lumens a piece. Better for the ratio.

Then.. to find how many led's needed to replace a hid...



But remember.. the 250w hps actually uses 300w, and the 400/600/1000w's use more as well. So when calculating Lumens per area, and efficiency.. calculate using 300w hps @ 28,000 Lumens.

28,000 Lumens = 280 led's set at 100 Lumens each.

2.3v 620nm red/orange @ 600mA = 102.3Lm
2.2v 630nm red @ 500mA = 103.46Lm
3.5v 470nm blue @ 900mA = 104.04Lm


Or... keep the reds at "typical" 350mA, and the blues at "typical" 350mA, but add twice as many blues.. ie instead of 8:1 red to blue, use 4:1 red to blue. Led's are most efficient at "typical".. ie: 50%. They only double in lumens by 80% at maximum.. 20% loss.

620nm: 2.1v @ 350mA = 62.0Lm
630nm: 2.1v @ 350mA = 73.9Lm
470nm: 3.2v @ 350mA = 30.6Lm


There's also the PAR measurements.. actual "used" spectrums from those Lumens. Led's are pretty much all usable light, as it's personally selected by wavelength.. compared to a hid, where there's "wasted" light that's emitted in the wrong/unusable spectrums. .. What that percentage is, I have no idea.. that's where aiming for 75% of the hid you're replacing is a good rule to follow. Maybe that's why they say they replace a hid twice the size? Look at an hps spectrum graph, and at least 50% isn't usable by the plant.



Cheers...........

umm you cant reliably measure led by lumen especially if it red or blue because lumen is weighted 555nm green so what you say is pure nonsense bro photon flux density is what matters and that was proven by the guy that sold me my panel 50000 HPS lumens versus 10000 'lumens' and 10000 won so lumens dont mean a thing bro

blue diodes are more efficient than red according to every spec sheet i showed my dad from nichia to seoul to cree to bridgelux

 

[Spuzzum]

umm you cant reliably measure led by lumen especially if it red or blue because lumen is weighted 555nm green so what you say is pure nonsense bro photon flux density is what matters and that was proven by the guy that sold me my panel 50000 HPS lumens versus 10000 'lumens' and 10000 won so lumens dont mean a thing bro

blue diodes are more efficient than red according to every spec sheet i showed my dad from nichia to seoul to cree to bridgelux

Actually.. it's 450nm blues, and below, that aren't measured in Lumens.. they're measured in mW.. energy, not luminosity. Same as the InfraRed 735nm's.

As for 50,000 Lumen hps compared to 10,000 Lumen led.. yes, I already said "at least 50% of the hps Lumens are wasted".

 

[kush groove]

How's it going guys just purchased my first led. I ended up getting the blackstar 240w and was wondering how many mature plants this single light could handle thanks for the help

2-3 plants should be fine

 

[kush groove]

I disagree I would rather swap fans often then swap lights often... Hot air coming out the side will just head up and back into the light if the fans are just blowing the hotter air from the higher points in the room where hot air is usually accumulated...Not useful.....Even the heat cause buy the small DC fan is passing threw the light B4 exiting..I don't think this the best way...I dont know about you man but my cpu is always fucking hot

what your considering heat definitely isnt hot enough to cause mechanical or electrical issues