COB Parallel Wiring. Need Help.

PCXV

PCXV

Well-Known Member
COBs: 9x CXM22 50v
Drivers: HLG 185h-48A

3 COBs wired parallel to each driver.

Driver's max output = 3.9A and 48V

1) How do I set up the internal trimmers for this configuration?

*Has Voltage (Vol ADJ) and Current (IO ADJ) trimmers. Right now, I have Voltage all the way up, and current set at ~1.2 amps per driver.

2) What temperature range is normal for these COBs/heatsinks?

*With setting above, heatsink temps range from 90F-110F (32-40C).

3) Do I need to add a resistor inbetween driver and each cob to prevent thermal runaway?

Thanks!
 
thetr33man

thetr33man

Well-Known Member
Turn voltage all the way down and current also. Once its all hooked up and plugged in turn up voltage till cobs light, once they are bright, turning it up more wont make them brighter, then adjust current to where you want it to be and you are done, no need to adjust voltage again. You could wire fuses in line with each of the cobs, but most likely if you loose one cob, the other 2 will be able to handle it until you can replace. If you are running cheap cobs might not hurt to keep an extra laying around in case one dies. Ive got the same driver wired to 3 citi 1818s on mecha 152-50 sinks and should be fine if one dies.
 
PCXV

PCXV

Well-Known Member
thetr33man said:
Turn voltage all the way down and current also. Once its all hooked up and plugged in turn up voltage till cobs light, once they are bright, turning it up more wont make them brighter, then adjust current to where you want it to be and you are done, no need to adjust voltage again. You could wire fuses in line with each of the cobs, but most likely if you loose one cob, the other 2 will be able to handle it until you can replace. If you are running cheap cobs might not hurt to keep an extra laying around in case one dies. Ive got the same driver wired to 3 citi 1818s on mecha 152-50 sinks and should be fine if one dies.
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Thanks for the reply.

I have a Kill-a-Watt power meter to measure watts and Amps as I adjust the trimmers.

The COBs are 50v and the power supply puts out 48v (up to 53v all the way up according to cobkits). You are saying when the voltage hits a certain point, say 30v, that turning it up more is either pointless or might hurt the COB? Is running at a lower voltage recommended?

After I get voltage set, I can measure the Amps and total Watts the driver is consuming. Right now the driver is pulling 1.2 Amps, which is 0.4 Amps per COB, correct?

According to the CXM22 spec sheet, typical forward current is 1.28 Amps per COB. Is 0.4 too low?

This next part confuses me even more. At 50v and 0.4 Amps per COB, the driver is pulling 135 watts according to my power meter. How is that possible?

If I do the math via voltage and current
50v x 0.4 amps = 20 watts per COB , 20 watts x 3 COBs = 60 watts.

If I divide the wattage per my power meter:
135 watts / 3 COBs = 45 watts per COB.

What am I missing here?
 
thetr33man

thetr33man

Well-Known Member
50v cob wont light up till its near 50v, you want it to just light the cob fully, without over volting it too much. You can only turn an A type driver current down 50%, so this is a 4A driver so turned all the way down it will be putting out 2 amps divided into whatever cobs you have hooked up. Amps of AC doesnt convert to amps of DC. 400ma is fine, it wont hurt anything. Thats basically a 200w power supply, so if you are using it at full power youll be giving each cob about 65 watts, half of that would be about 30 watts, with the current adjustment turned all the way down.
 
PCXV

PCXV

Well-Known Member
thetr33man said:
50v cob wont light up till its near 50v, you want it to just light the cob fully, without over volting it too much. You can only turn an A type driver current down 50%, so this is a 4A driver so turned all the way down it will be putting out 2 amps divided into whatever cobs you have hooked up. Amps of AC doesnt convert to amps of DC. 400ma is fine, it wont hurt anything. Thats basically a 200w power supply, so if you are using it at full power youll be giving each cob about 65 watts, half of that would be about 30 watts, with the current adjustment turned all the way down.
Click to expand...
Awesome that info helps a lot. Just a couple questions to clarify:

My power meter reading 1.3 amps is what my driver ia pulling in AC and isn't the same as what my drivers are feeding my COBs in DC?

With the current trimmer turned all the way down to 2A, each cob is recieving approx. 667ma. I was confused by the 400ma figure because that was the AC current being divided not the driver output.
 
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