Need some help with the numbers

Hi, i am a pretty DIY guy and i like to set up things so when a friend teached me how to grow i got there pretty quickly with a HID light and then after i tried lots of things like CFL's, some cheap leds, even bought those dirt cheap 50W cobs from ali express.
I can't mesure ppfd's, the tool is too expensive for a hobby, i have a 2 meter tent for growing and i'm using a closet for the babies and clones, basicly did 3 harvests and now wanted bigger buds and to improve my grow so i tried the cheap cobs and after reading a lot about light and saw the migro light and all the guy's videos on youtube now i wanted to make my own. I found this forum that way, googling for the light so i think that i will go with the
CXM-32-35-80-54-AC00-F2-3
Is this the one he uses?
Since i already have some big aluminium heatsinks that i used for the cheap cobs (also used a 140mm fan from a power supply, so, activly cooled) all i need is the COB from Luminus (the right one) and now my questions:
I want to use 2 of these so wich power supply to buy for them? the ELG-240-C2100A? they will be mounted like 2 in one side of the tent and if this works later 2 on the other side so i just wanted to order the cob led and the power supply to make these 2 and more in the future.
Another question is i see people talking about Graphite pads instead of cpu thermal paste, wich was what i used (bad idea ?)
And lastly, what lens to use, if any ?

Thanks in avance and i hope to learn here since i already read quite a few threads and found a lot of good info.

Welcome.


Here is the data sheet ^^, the part number tells us its an 80cri COB in 3500 kelvin with a voltage of 54 , running at 2100mA it will be around 51-51.5v per cob Which will work out at 107w-108w each.
That driver can take 57-115v so you can fit 2 on there easy and they will pull 214w ish.

Not sure which is more conductive for TIM but there is nothing wrong with CPU thermal paste.

In a tent no need to use a lens or reflector.

Running 100w+ a COB you want to make sure your heat sinks are up to the task.

3500k Is a good all round spectrum so I wouldn't be surprised if it is the one migro uses.

Hope that Helps.

Thanks coreywebster it really does, it means i was following the right path

One question, if one of the COB's fails what happens ? the power supply will burn the other one ?

droidman said:

thermal paste,

Click to expand...

paste is best.

droidman said:

One question, if one of the COB's fails what happens ? the power supply will burn the other one ?

Click to expand...

I will let Corey answer your question correctly lol but just basic electronic theory... Are they to be wired in series or parallel? If wired in series then if one dies the circuit is broken and the remain COB's on that string would lose power but should be fine. If wired in parallel the resistance of that chain would increase if a COB failed and that would cause the current to drop (don't use a constant current driver). I will let Corey suggest a driver as he's the man when it comes to LED lights, I am just learning myself. You are in good hands.

Thank you Renfro i really dont know for sure what method i will use, if someone suggests a safer method i will use that one.
On my current cobs i just connected the positive wires and negative wires to mains cuz they are like that, directly to the wall without any adapters and they are working like this for months and they work, but since these dont cost 1€ each i really want to go pro on this one