LED lighting on a budget!
- Thread starter kcress
- Start date
Floyd R Turbo
Either busy or sleeping
Yes, apparently I was right. I thought I was, but I wasn't 100%. This is why I went with the DIY driver. 1 board for about $50 and 2 PSs for about $40 each can drive 48 LEDs while 1 Meanwell ELN at $100 can only drive 12 LEDs. My decision was also driven by the fact that I would have needed 8 ELN to drive 96 lamps and that's a lot of power on home wiring.
TheFishMan65
New member
ELNs run $25 to $34.
Also
"If you are running 48 LED, 24 on a side, you would need 500W (24 VDC, 20A) total to run that board. "
is not correct. 48 LEDs is 8 string of 6 LEDs. 8 strings at 1 amp ould be 8 amps total. To the power supply only needs to be about 200 watts or 2 supplies of 100 watts,
Also
"If you are running 48 LED, 24 on a side, you would need 500W (24 VDC, 20A) total to run that board. "
is not correct. 48 LEDs is 8 string of 6 LEDs. 8 strings at 1 amp ould be 8 amps total. To the power supply only needs to be about 200 watts or 2 supplies of 100 watts,
Floyd R Turbo
Either busy or sleeping
Sorry, I got confused on the pricing. I was thinking of a different PS.
And yeah whoa I was way off on the DIY driver power supply. Not sure what I was thinking. This week has been hellish....
And yeah whoa I was way off on the DIY driver power supply. Not sure what I was thinking. This week has been hellish....
I'm getting rerady to do my own DIY and thought maybe you guys might find this page interesting. 
http://www.mmmetals.com/pages/extrusion_profiles/aluminum_extrusion_profiles.htm
http://www.mmmetals.com/pages/extrusion_profiles/aluminum_extrusion_profiles.htm
Floyd R Turbo
Either busy or sleeping
Yeah, I found that one too in my search. Not much difference in price and still quite a bit of overkill. Read kcress' post # 157...
Floyd how were you able to compare prices? Did you need to call them?
Another option I haven't seen anyone mention is the use of 3/8" flat stock. This can than be placed on a table saw and fins can be ripped into the stock. The use of bee's wax and a carbide blade make quick work of this. Several shallow passes are done on each "groove" but the outcome can be very nice. We used this technique at work to create 2 custom 24"X24" heatsinks for a piece of equipment that was suffering overheating issues. 2 years and still running cool with these.
Floyd R Turbo
Either busy or sleeping
I didn't really bother much with it, because they're all pretty close together price wise - maybe 10-20% cheaper depending on where you look, but the the difference is usually narrowed when you factor in shipping and cuts.
What it comes down to is the reality of the nature of LEDs and their ability to get really frickin hot and still work just fine. Plus factoring in that at the current pace of development (as pointed out by kcress) the LEDs that will be available in 3-5 years will dwarf the present ones in efficiency (lumens/watt) and in price (less). So if you're willing to DIY it now and be on the cutting edge, chances are that you will want to upgrade to a more efficient (more lumens/watt) and cheaper (on lumen/watt basis) lamp 5 years from now. That's where I'm coming from - now.
What it comes down to is the reality of the nature of LEDs and their ability to get really frickin hot and still work just fine. Plus factoring in that at the current pace of development (as pointed out by kcress) the LEDs that will be available in 3-5 years will dwarf the present ones in efficiency (lumens/watt) and in price (less). So if you're willing to DIY it now and be on the cutting edge, chances are that you will want to upgrade to a more efficient (more lumens/watt) and cheaper (on lumen/watt basis) lamp 5 years from now. That's where I'm coming from - now.
BluScrnOdeth
Darin Schmidt
OK, here is my situation.
I have the Cree 3w LEDs, XPG CW and XPE RB's. A 48v 5A psu from circuit specialists. I didnt know before hand that it has a voltage adjuster on it so i bought some 5w resistors, 2.5ohm. 14 CW on one array and 14 RB on the other. According to the calculations in the first post, i only needed 1.8ohm 2.xx watt resistors. I was originally wanting to run them at 3.3v (46.2V total) but decided to use all the voltage 48/14=3.43V per each LED. Which should push both types of LEDs close to 1000mA.
But i noticed some smoking once i got it all connected yesterday.... So i turned it off and put on another resistor and everythiong seems to be ok now. But what i want to know is WHY i seen smoke come from my LEDs with following the equations on the first page??? I technically shouldnt even need a resistor because the LEDs are capable of handling up to 3.5V. Am i misunderstanding something??? I do have a 1.1A inline quick burn fuse. They are all thermal pasted to a 8.5"x18" aluminum heatsink also so heat isnt an issue as its barely warm to the touch and has 2 80mm 24v (in series) fans connected to the PSU as well.
I have the Cree 3w LEDs, XPG CW and XPE RB's. A 48v 5A psu from circuit specialists. I didnt know before hand that it has a voltage adjuster on it so i bought some 5w resistors, 2.5ohm. 14 CW on one array and 14 RB on the other. According to the calculations in the first post, i only needed 1.8ohm 2.xx watt resistors. I was originally wanting to run them at 3.3v (46.2V total) but decided to use all the voltage 48/14=3.43V per each LED. Which should push both types of LEDs close to 1000mA.
But i noticed some smoking once i got it all connected yesterday.... So i turned it off and put on another resistor and everythiong seems to be ok now. But what i want to know is WHY i seen smoke come from my LEDs with following the equations on the first page??? I technically shouldnt even need a resistor because the LEDs are capable of handling up to 3.5V. Am i misunderstanding something??? I do have a 1.1A inline quick burn fuse. They are all thermal pasted to a 8.5"x18" aluminum heatsink also so heat isnt an issue as its barely warm to the touch and has 2 80mm 24v (in series) fans connected to the PSU as well.
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BluScrnOdeth
Darin Schmidt
CW XPG
14*3.3V=46.2
48v-46.2v=1.8v
1.8v/1.0mA=1.8ohm
1.8v*1.0mA=1.8watt *2 = 3.6watt
RB XPE
48v/14=3.42v
14*3.42v=47.88v
48v-47.88v=.12v
.12v/.8mA=.15ohm
.12v*.8mA=.01watt
and i currently have 2 2.5ohm 5watt resistors connected because 1 2.5ohm resistor wasnt stopping enough current somehow and causing something to smoke. The dang LEDs were so bright i couldnt see what it was even when i tried to cover them so i wouldnt blind myself.
14*3.3V=46.2
48v-46.2v=1.8v
1.8v/1.0mA=1.8ohm
1.8v*1.0mA=1.8watt *2 = 3.6watt
RB XPE
48v/14=3.42v
14*3.42v=47.88v
48v-47.88v=.12v
.12v/.8mA=.15ohm
.12v*.8mA=.01watt
and i currently have 2 2.5ohm 5watt resistors connected because 1 2.5ohm resistor wasnt stopping enough current somehow and causing something to smoke. The dang LEDs were so bright i couldnt see what it was even when i tried to cover them so i wouldnt blind myself.
BluScrnOdeth
Darin Schmidt
you could just use this unless you are after the stats of the meanwells.
48v 5A
http://www.circuitspecialists.com/prod.itml/icOid/9625
TheFishMan65
New member
I think the problem is that LEDs can vary at least 10% and maybe as much as 20%. This is why it is not recommended to run directly from a power supply IMHO. Calculationns only work for the average LED, but there is not such thing as an average LED.
If you inssist on doing it this way. I would use resistor with about 1/4 of the current you are expecting and work your way up. A 0% change in voltage could have a much larger change in current.
If you inssist on doing it this way. I would use resistor with about 1/4 of the current you are expecting and work your way up. A 0% change in voltage could have a much larger change in current.
BluScrnOdeth
Darin Schmidt
Thanks fishman, I'm gonna have to figure a way to get my meter connected to the LEDs because it sure is freakin bright. Thank god the PSU i have has an adjustable Voltage.
TheFishMan65
New member
I posted this somwhere and if I remember. I had a string of LEDs running at 700ma. I had one with a vf of 3.2 or 3.3 most around 3.4 and one at 3.7. So maybe I hsoud have saidn +/- 10% or perhaps more.
BluScrnOdeth
Darin Schmidt
what did you use to cover the LEDs to measure them? i was thinking about getting somer cardboard from work tomorrow to lay over them and have a whole cut out for just one LED to shine through. that should be manageable.
TheFishMan65
New member
My driver was far enough away that I could measure it there. I also had the LED pointed down toward the floor (dark carpet, they didn't touch the carpet).
BluScrnOdeth
Darin Schmidt
well in any case, i figured i would show my unit i made that seems to be working really well.
before with 32 350mA Cree's 50/50 CW RB:
<img src="http://www.aquatic-refuge.com/RandomPics/350mAlighting.jpg" width="600">
28 LEDs roughly 900mA (have to test with a meter still)
<img src="http://www.aquatic-refuge.com/RandomPics/LEDunit3.jpg" width="600">
here is the unit:
<img src="http://www.aquatic-refuge.com/RandomPics/LEDunit4.jpg" width="600">
how bright it is:
<img src="http://www.aquatic-refuge.com/RandomPics/LEDunit1.jpg" width="600">
my unit isnt completely assembled yet. got to get a couple other parts for it. Should have it finished in a couple weeks when i can get the time to get it done.
before with 32 350mA Cree's 50/50 CW RB:
<img src="http://www.aquatic-refuge.com/RandomPics/350mAlighting.jpg" width="600">
28 LEDs roughly 900mA (have to test with a meter still)
<img src="http://www.aquatic-refuge.com/RandomPics/LEDunit3.jpg" width="600">
here is the unit:
<img src="http://www.aquatic-refuge.com/RandomPics/LEDunit4.jpg" width="600">
how bright it is:
<img src="http://www.aquatic-refuge.com/RandomPics/LEDunit1.jpg" width="600">
my unit isnt completely assembled yet. got to get a couple other parts for it. Should have it finished in a couple weeks when i can get the time to get it done.
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