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Need some advice on an LED project

Rick P

Mar 24, 2015
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Greetings Electronics Guru's
I'm new to this and need some advice on an LED fixture I'm designing for retail. It's an LED Grow Light for indoor gardening. It is a 2'x4' fixture made from formed sheet aluminum. It has 4 LED modules adhered to the sheet aluminum. The modules are 44" long and 3/4" wide. Each module requires a constant current 54 vdc at 1.4 amps. I was previously using 150 w drivers that produce 2.8amps at 54vdc for every two modules. I worked with the driver manufacturer and produced a combo driver - it has two 150w drivers in one case. It has a power receptacle and three way selector knob on one end and a 4 pin DIN receptacle on the other end. The knob selects which driver is getting power. Position A lights up the two inside modules, Position B lights up the two outside modules, and Position C lights up all modules. I use the same 4 pin DIN receptacle on the fixture side and have a 10-15' cable with male 4 pin DIN connectors to connect the driver and the fixture.

SO here is my questions: The 4 pin DIN connector I am using lists a max voltage of 48v at 7.5 amps. I am under amps but slightly over volts. Does anyone know of a better 4 pin connector that I can use to connect the fixture and the driver? I want to keep the two pieces separate and connected with a cable. If there is not a standard connector that will work with those specifications can anyone recommend a manufacturer of connectors who can make something custom for me?
 

BobK

Jan 5, 2010
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You cannot connect two lamps in parallel to a constant current driver. There is no guarantee that they will share the current equally. And worse yet, when one gets more current than the other, it heats up more, which, for LEDs causes it to take still more current until it is destroyed.

Bob
 

Rick P

Mar 24, 2015
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Mar 24, 2015
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Thanks for the reply Bob but that is how the manufacturer of the modules instructed me to wire it. Depending on what size driver I am using I can wire one or more modules to the driver. For instance I have a 300w driver in one fixture that has 4 modules connected to it. The 300w driver produces 5.6 amps so each board uses 1.4 amps.

Any suggestions on the 4 pin connectors?
 

BobK

Jan 5, 2010
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For instance I have a 300w driver in one fixture that has 4 modules connected to it. The 300w driver produces 5.6 amps so each board uses 1.4 amps.
There is nothing to ensure this. Each lamp will have a slightly different forward voltage, causing the current to be divided unequally. As I stated before, the forward voltage also depends on temperature, so, unless the temperature of each lamp is kept identical, the division of current will change. And the change is in the direction of amplifying the differences. See here for information about how to drive LEDs:

https://www.electronicspoint.com/resources/got-a-question-about-driving-leds.5/


Bob
 
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