Cali Kid Corals

Need help with my DIY led setup

davskee

davskee

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Can anyone help me figure how much power to run to my leds. Below are the LEDS and drivers im using.

18 XPG cool white (running 2 series strings of 9 in parrellel)
18 XPE royal blue (running 2 series strings of 9 in parrellel)
2 meanwell 60-48d

And I just noticed when looking at the picture I forgot to wire up 1 white LED!

led.jpg
 
What do you mean how much power to run to your LEDs? The XPE Royal Blues can handle 1000mA, the XPG whites 1500mA, the drivers you got can output up to 1300mA, if memory serves. So first and foremost you'll what 2 1000amp fuses on your blue strings, so if something bad does go wrong.. i.e. blown LED on one string that stays closed, then all the current will go through the other parallel string which will promptly fry them as well.

When you split it in parallel you'll split the current, so you can run the drivers at full current if you want, just put the fuses in as a safety measure (safety for your wallet of frying 9 LEDs all at once )
 
Yes, unsure of the question.
Your power supply can only drive 1.3A, split in 2 parallel = 650 mA.
So you are well under LED spec limit. No power issue.

If you want total power used:
Both XPE and XPG are about 3.2 Vf at that current, so 28.8V total for 9.
28.8v * 1.3A * 2 = 75 Watts.

+1 on the fuses.
(Although I am not a fan of running the strings in parallel anyway)
 
I thought if you run 2 series string of 9 each and parrellel them it will cut the power to about 650mA. So im guessing I run the drivers at max and the leds will run at about 600-650mA. Is this right? So if this is true I dont have to worry about blowing these LEDs cause I will be driving them under the max output.
 
davskee said:
I thought if you run 2 series string of 9 each and parrellel them it will cut the power to about 650mA. So im guessing I run the drivers at max and the leds will run at about 600-650mA. Is this right? So if this is true I dont have to worry about blowing these LEDs cause I will be driving them under the max output.
Click to expand...

Yes, those numbers are correct.
Balance will not be perfect, especially over time, but will be ok.

The problem is if one LED fails. They usually fail open (so no longer conduct)
At that point, all of the current goes down just one strand. (1.3A)
That is not a problem with XP-G, but will eventually kill XP-E, so best to add a fuse.
 
So do I run a fuse each series string or after I parrellel them? And what amp fuse should I run down each string (XPG and XPE)?
 
Each series gets a string, you'll put 1300mA across the whole thing so if you fuse the whole setup you'll burn the fuse out when you turn it on :D

Of course if you want to dispense with the fuses you can simply dial it down to 1000mA, but then again I assume you want to dim the thing, so you don't want to accidentally undim too much.
 
Im not sure how to put a fuse on the blues. If I put a 1000ma fuse on it it will blow cause im running @ 1300mA(650mA to each string). Im unsure how to do this. Should I put a resistor of some kind on each blue string to only allow 650mA? Is this possible?
 
You need a fuse on each sub-string, after you split them into parallel, where it is 650mA, not 1300mA.
So, 4 fuses total, each 1A.
 
Think of each thing in a circuit as an "element" connected by "wire" and they provide a "function" so your LEDs are each elements connected by a wire from the + side to the - side, and they provide a function of making light (and heat:D) A fuse is no different, you put it in like any other element (obviously you'll need a fuse holder itself which is what you solder wires to), the only difference is it is designed to fail in an open state if the current exceeds its specs.

If you put 2 fuses, either after your wire splits, or before they rejoin you won't put putting 1300mA through the fuse, you'll put 650mA across it. Resistors won't work in this case because the current that's in your wires is fixed, it's not dependent upon the voltage, so 1300mA will go right through your resistor and into your LEDs, its not a failsafe at all, remember drivers are fixed current sources, not voltage sources, most things that make DC power we deal with are voltage sources, so each object will draw whatever current it 'needs' based upon the voltage.

Now if you want to get spiffy/creative, you can put a couple high power low resistance resistors on each string as well, 3watt- 1ohm resistors, and using a volt meter simply measure the voltage across the resistor and that will equal the current. Nice way to measure current in your LED setup without disconnecting wires (which you'd have to do if you measured the current directly)
 
sfsuphysics said:
FYI I don't know that I'd bother with fuses on the white string, they are rated for 1500mA max, they'll be fine if one blows open.
Click to expand...

Not only that, but it is very likely you will be lowering the current on the XP-G strings anyway.
They are more efficient, so at same count and current, the overall color temp will tend toward the white.
 
Ok on the blue strings i will put 1amp fuses before I parrellel them. Just want to make sure. And BIG thanks for all the help guys. I kinda knew what to do but just wanted to be sure before I blew up these LEDs!!!

I do have an extra driver and maybe ill get another but for now Ill try 2.
 
no dude! not before you parallel them, in the parallel string with them!


Code: 
	            ---- fuse --- led --- led --- etc----
	driver--|                                                | -- (back to driver)
	            -----fuse --- led --- led --- etc----

ok apparently the code function is busted here :D
 
Sorry for the bad pictures used my cell phone. Currently no optics but I do have 80 degrees. Now all is left is to retro this into my fixture.

led1.jpg


led3.jpg


led2.jpg
 
Looks good Dave, sorry I didn't see your message until this morning, but doesn't look like you blew anything up :D I had a minor plumbing emergency, fixing one leak, ended up requiring me to replace a whole length of copper tubing :D

Anyways, plan on putting any sort of optics on that?
 
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