DIY LEDs - The write-up

[kcress]

Just used a kill-a-watt to test two DIY led arrays that run fine in terms of producing light. Both are pretty standard builds based on info from this and related threads (thanks)- 12 Cree leds each, mostly RB & CW with a couple NW, connected to Meanwell drivers (running at ~900mA). One of the arrays uses about 34 watts, the other is reading ~54 and I can't figure out why. I switched the drivers and still get the same result for the same array so that I assume the issue is with the leds and their connections. Any ideas on why one array is consuming about 60% more power than it should?

The two arrays might differ in the ratio of colors, but they are all 3W leds and I don't see why color would matter (other than efficiency of converting the 3W to light). The arrays were built at the same time using the same gauge wire, solder, etc.

Could it be heat? The higher consumption array is on aluminum u channel rather than a proper heat sink...but it reads the same power usage just after it turns on as after it has been running for a while so heat doesn't seem likely either.

Could there be a little current leaking through the ground wire from a bad solder? I'll check that tonight, but I thought that such a situation would just short the unit.

Thanks for any ideas.

Measure the voltage and the current feeding the entire arrays for the two drivers.

 

[kcress]

As for terminal blocks look at the second shot in this post:
http://www.reefcentral.com/forums/showpost.php?p=18768903&postcount=170

That's what you're trying to achieve. You might need longer terminal blocks.

 

[patmack]

Im just horribly impatient and cant wait for things to get here in the mail so I went to radio shack. :bounce3::hammer:This is what I got.
http://www.radioshack.com/product/index.jsp?productId=2103986

 

[tonythefish]

What Cree LEDs are you using ? There is a Difference in power consumption. I do not have the specs in front of me but I believe it is on the spec sheets on Cree's site

XR-E ?
XP-E ?
XP-G ?

R3, R5

 

[bmwaaron]

Would it be possible for someone to post or send me a PM with the best places to buy the Cree LED's?
I know of a couple of the venders but sounds like there are some better vendors with cheaper prices.
Im looking for RB XP-E and the newer CW XM-L
Thanks for the help.

 

[James77]

Roughly how far do LEDs, with the thermal paste and optics, stand off of a heatsink? I'd imagine their is some variance, but Im looking for the XPE RB. Are different degree optics still the same height? (ie if a 60* optic is 3/4" high, is an 80* as well?

 

[dlp211]

Instead of terminal blocks, can I use butt splices to drive my strings? I am getting 2 HLG 185-48b and will be driving 12x4 xpgs @ ~1a and 12x5 xpes rb @ ~.7a. I just really hate the look of terminal blocks.

Thanks
DLP

 

[TheFishMan65]

You can but replacing fuses will be harder.

 

[kcress]

Terminal blocks will be more reliable.. There are several types. You should be able to find one that suits your aesthetics.

 

[dlp211]

I think I will use the Euro style ones then. Oh one other quick question. I have the HLG 185-48b, do I need to use a potentiometer, or can I leave it with no dimming capabilities initially. My final setup will be connected to an Apex.

Thanks
DLP

 

[kcress]

Yes you need the pot(s). Otherwise you will be commissioning your fixture at full power which significantly increases the risks.

 

[Jimmy54]

The HLG-B’s are on their way - and so are the DDC-01 PWM controllers, which I’ll be using for adjusting and dimming the LEDs.

Before installing the controllers, I first would like to test the fixture through the resistor option; is there a special kind of pot I need?
Or is it an average 100K ohm pot that will do the job?

Thanks in advance.

 

[gmigmi]

first thanks to all contributers to this thread, great info.
I am planning a build for my tank I will begin with 2 units of 60 leds each 50/50 xpe rb and xpg cw and maybe change some to nw.
I have a few questions (I'm sure I'll have more down the road)

On the HLG 240-48 how many parallel strings of 12 can I do maximum for xpg or xpe? would 6 strings be too much?

Jimmy54 first thanks for the help in pm, I would like to understand better what got you to go on the xml rather then xpg, for what I can find the xpg costs approx $5 led+lens and the xml t6 approx. $12+ led+lens, while the price is more than double, the lumen/watt in only 15-20 percent higher, so efficiency is not that much better. are you planning on running them in higher ma than the xpg max?

 

[patmack]

Do you plan to dim your LEDs? The HLG 240s only go down to 50% if you want to dim down to 10% you need to go with the HLG 185's

first thanks to all contributers to this thread, great info.
I am planning a build for my tank I will begin with 2 units of 60 leds each 50/50 xpe rb and xpg cw and maybe change some to nw.
I have a few questions (I'm sure I'll have more down the road)

On the HLG 240-48 how many parallel strings of 12 can I do maximum for xpg or xpe? would 6 strings be too much?

Jimmy54 first thanks for the help in pm, I would like to understand better what got you to go on the xml rather then xpg, for what I can find the xpg costs approx $5 led+lens and the xml t6 approx. $12+ led+lens, while the price is more than double, the lumen/watt in only 15-20 percent higher, so efficiency is not that much better. are you planning on running them in higher ma than the xpg max?

 

[patmack]

As far as the XMs go what current should they be ran at? Will 3 amps burn the corals? I don't know if ppl are running them at higher currents and using less LEDs.
How much more efficient are the XML than the xpg at 1 amp?

It seems like there isn't enough info out there on them for us using them over our reefs.

 

[gmigmi]

I'm not planning dimming on a daily basis, maybe just a bit initial for color balance so %50 is more than enough.

 

[gmigmi]

As far as the XMs go what current should they be ran at? Will 3 amps burn the corals? I don't know if ppl are running them at higher currents and using less LEDs.
How much more efficient are the XML than the xpg at 1 amp?

It seems like there isn't enough info out there on them for us using them over our reefs.

If I'm not mistaking the efficiency difference at 1 amp is around 15-20 percent, and running them at 3 amps even with wide optics (as far as I have seen there aren't any really wide optics available yet for xml) doesn't seem to give too much option of using less led's since this would give a uneven spread of the light.

 

[Jimmy54]

Jimmy54 first thanks for the help in pm, I would like to understand better what got you to go on the xml rather then xpg, for what I can find the xpg costs approx $5 led+lens and the xml t6 approx. $12+ led+lens, while the price is more than double, the lumen/watt in only 15-20 percent higher, so efficiency is not that much better. are you planning on running them in higher ma than the xpg max?

Hi, Israel,

Guess I wouldn't even concider buying the XM-L for $12,- while they're out there - e.g. China - for around $7 The NW's were $6,95 in the US.
So yes, 20% more efficiency was the primary reason, also having the ability to run them at much more lumens than any other LED pulled me over the line.
(which indeed isn't more efficient, unless you buy fewer XM-Ls then if you had chosen for XP-Gs)
But for now I think/hope I don't need to run them any higher than @ 1000mA

On the HLG 240-48 how many parallel strings of 12 can I do maximum for xpg or xpe? would 6 strings be too much?

When running the XP-G @ 1000mA, you can have 5 strings of 12 LEDs (5A is the max output of the HLG-240-48)
Run them @ their max - 1500mA - and you will be limit to have 3 strings of 12 LEDs
It's pretty basic, dividing the drivers' output-voltage by the LEDs' Vf, will give you the number of LED's in a string.
Dividing the drivers' output-current by the amp's you're planning to run your LED's at, will give you the number of strings you can have.

 

[Jimmy54]

If I'm not mistaking the efficiency difference at 1 amp is around 15-20 percent, and running them at 3 amps even with wide optics (as far as I have seen there aren't any really wide optics available yet for xml) doesn't seem to give too much option of using less led's since this would give a uneven spread of the light.

Don't underestimate ~1000 lumens per LED.
Supply them with 5/10° optics, run them @ 3A and you can illuminate your tank from the second floor with halve the amount.

 

[kirsto71]

I need some help with the wiring of a potentiometer for my new drivers. I bought Thomas research drivers and had already got 10k pots (from a friend who had them spare) but when i had a look at the diagram on the spec sheet for the driver it had a diagram suggesting that the driver should use a 20k pot. Why the difference and what is the difference.

The driver has 10v out, 0-10v input and ground wiring. I have done a little research and it would suggest that (looking from the top down).

Pin 1 (Left) - 10v Power in
Pin 2 (Middle) - 0-10v signal into driver
Pin 3 (Right) - Ground

Also i will be hooking up 10 Cree XP-G LEDs to the driver (approx 35 volts) so as per note 2 at bottom of diagram i assume that because i am operating at >50% of the max output i will be able to dim across the entire range?

Any help with this is greatly appreciated.