Question about wiring COB's in series (Specifically Cree CXA3590)

K

Kapok6

Member
Alright, I am sure this has been answered before, but I can not find the answer anywhere, including from Cree.

So here it is. I want to run 2 Cree CXA3590's in series with 1 driver. My question is, does anyone know the Min-Max Voltage range of these things? I know they have a forward voltage of 77v, (the 5000k ones I am looking at do anyway). So I was eyeballing MeanWell HLG-240H-C1400A. It's rated at a voltage range of 89v-179v and 700ma-1400ma. Now, with the min voltage output of this driver being 89v, and knowing that sometimes COB can "blow closed" if that happened, and one operational LED was to see 89v, is it going to blow that LED too due to over voltage, or could that LED handle it?

I have already done a similar setup with two CXB3590 3000k 72v LED's powered by a HLG-185H-C1400 which has a voltage range of 71v-143v, so even if one of those blows closed, it will not send too much voltage to the still operational LED.

The flip side to this is, what if I were to use the HLG-185H-C1400 (71v-143v) driver to run two of the 77v COB's? 77+77='s 154v. Max output of that driver is 143v. I'd be running it at the edge of it's output and still be 11v short. Would that be an issue, or will they still operate being 11v short?

I wish tone could be interpreted, so don't take this the wrong way, but I am looking for definitive answers from people who know, not conjecture from people guessing. This equipment is too expensive to just buy parts and experiment with and hope it works out.

Thanks in advance for the info.
 
Rahz

Rahz

Well-Known Member
If one of the CXBs quit working the series wouldn't be drawing enough voltage from the 240. The driver should shut down.

2 3590s on the 185 would be over the voltage rating. The driver would lower the current until the voltage was within spec which would be about 1 amp.
 
K

Kapok6

Member
Correct me if I am wrong, but my understanding of you response is that either could be used, but they will react differently, correct?

If I use two CXA3590's with the 240, if one blows closed so current still goes through it, you are saying the one remaining LED won't draw enough voltage, so the system will just stop working until I were to replace the blown LED, right? Is that all that would happen? That scenario doesn't sound bad if there is nothing else that sees damage, and all i'd have to do is replace one COB to get the system back up and running.

If I use two CXA3590's (77v) on the 185-1400, you are saying the driver can't provide enough voltage so the driver would automatically lower the amperage? My Understanding was that the amperage is manually adjustable via internal potentiometer, (type A).

How about the 185-1050? That would provide enough voltage for two like the 240, 1050ma.

I personally like the idea of the 240h-c1400a better if that will work as I can dial the amperage down to 1-1.2 if I want.

Thoughts on the best driver for this scenario?
 
Rahz

Rahz

Well-Known Member
That's all correct. The driver will lower amperage til it runs within spec, also manually adjustable via screw with the A series. Whether you go with the 185-1050 or 240-1400 just depends on what you're wanting the max output to be. The chance of cob failure during the warranty period should be pretty low so no major reason to avoid a series circuit.
 
K

Kapok6

Member
Well, I am looking at it like this in regards to the 240:

Pros: Less equipment/hardware. I can run two LED's off 1 Driver
Adjustable from 700ma-1400ma which would allow me to dial it down to the 1.2a I wanted to run them at
94% Efficient

Cons: If one COB goes out, the driver will no longer operate until I replace the COB, so instead of one light not being on, I now have 2 lights being on.
Almost 3x the cost of LPC-100-1050

LPC-100-1050

Pros: Less expensive than the 240 (would cost me $20 less to buy 2 than to buy one 240)
If one driver or LED craps out, it would have no affect on the others

Cons: More hardware to wire since I would need to wire individually
90% efficient compared to 94% on the 240
Will only run 1050ma instead of the 1.2ma I wanted to run

That being said, what direction would you go if in my position? How much affect in regards to amount of light provided will 150ma less really have? If negligible, I am probably leaning towards 2 LPC-100-1050's for the sole reason that if one driver or LED goes out, it won't affect anything else...
 
Rahz

Rahz

Well-Known Member
Amps x volts x efficiency = par watts, so you can get an idea of the relative intensity between them that way. I personally have no issues running cobs in series, and would go with the 240. You can also consider the LPF series drivers D version for running singles and dim to 1.2.
 
K

Kapok6

Member
Rahz said:
Amps x volts x efficiency = par watts, so you can get an idea of the relative intensity between them that way. I personally have no issues running cobs in series, and would go with the 240. You can also consider the LPF series drivers D version for running singles and dim to 1.2.
Click to expand...

Did you have a particular model you saw that would work with the 77v 3590's? All the LPFD ones I am seeing on MW's site only go up to 54v.
 
C

churchhaze

Well-Known Member
Rahz said:
If one of the CXBs quit working the series wouldn't be drawing enough voltage from the 240. The driver should shut down.
Click to expand...
The driver would not shut itself down. It would act like a voltage source with V=Vmax. (it's not the driver lowering the current, it's the load)

The 2 arrays in series would draw significantly less currently if one of the cobs was damaged, but there would still be max voltage across the series.

To answer the question, one going out would protect the other by limiting current.

Edit: I think I misunderstood Rahz's response at first because of "drawing enough voltage". Draw implies current/flow. Voltage drops.
 
Last edited:
K

Kapok6

Member
churchhaze said:
The driver would not shut itself down. It would act like a voltage source with V=Vmax. (it's not the driver lowering the current, it's the load)

The 2 arrays in series would draw significantly less currently if one of the cobs was damaged, but there would still be max voltage across the series.

To answer the question, one going out would protect the other by limiting current/flow.

Edit: I think I misunderstood Rahz's response at first because of "drawing enough voltage". Draw implies current. Voltage drops.
Click to expand...
So which of the proposed scenarios I laid out above would you suggest in regards to powering the 3590s?
 
C

churchhaze

Well-Known Member
Kapok6 said:
So which of the proposed scenarios I laid out above would you suggest in regards to powering the 3590s?
Click to expand...
I wouldn't worry about one cob shorting itself. I've never seen that happen. Even if one die in one of the cobs were to blow closed (unlikely), there are still many more in the chain.
 
C

churchhaze

Well-Known Member
Kapok6 said:
So your vote would be the 240 with them in series instead of driving them individually with the LPC?
Click to expand...
Yes, HLG-C works great. IMO, it makes sense to use higher voltages. (upto 400V where it becomes a lot more dangerous)

Btw, Rahz was giving good info, I just read what he was saying wrong.
 
K

Kapok6

Member
Right now I have some single 3590's on their own HLG-120H-C1400A's that work great. I also have two of the 72v 3590's in series being driven by an HLG-185h-c1400a. The 5000k ones are 77v though, so that threw a monkey wrench into it.

I guess I am just going to have to decide if it is worth an extra $20 to use a single 240 as opposed to saving $20 and running two LPC's.
 
K

Kapok6

Member
All this COB Driver stuff is like a complex game of design and mathematics. Another option that I am looking at is running 3 Vero 29's in series with an HLG-240H-C2100A.

http://www.mouser.com/ProductDetail/Mean-Well/HLG-240H-C2100A/?qs=/ha2pyFaduh5bsFxxMyVN259tdk1xLHvynGnWtPusX%2bezcGbxdIwUg==

The Vero's are rated at 38.6vF 2.4A, this driver will put out 119v 2.1A, so it should be enough voltage and will run the COB's a little light on current.

The Vero's are like half the price of the Cree 3590's, which is a selling point for me.

Ughhh...decisions decisions.
 
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