Driver Help please

After taking some readings with my PAR meter I decided now would be a good time to go all LED.

I want to save some money and use parallel circuits instead of buying 2 more drivers.

I may be confusing myself by using this LED parallel array wizard because it will only use standard resistors up to 1W. This build will use 5W 1 ohm X2 and 1000mA fuses X2 per paralell.


As the calculator is set up source voltage can only be set at 36 max before there are concerns about the power being dissipated by the resistors.

The wizard says at 48V the dissipated power is 18ohms. Does that mean I will need to use 5W 18ohm resistors or do I adjust the power with the SVR so that the source voltage is 36?

 

mumbo jumbo bump

 

No one wants to show off their superior electrical knowhow? That's surprising.

 

Might electrical know how is don't put your finger in a live socket, specially when wet.

Good luck Mike.

 

LOL thanks for the bump John

 

I've got some experience with electronics and DIY LED builds. However, the answer to your question depends on the wattage of your LEDs and the driver that you are using. For instance, the common ELN-60-48D by Mean Well can only drive a single string of up to 14 LEDs. For your project, you may want to look in to the Mean Well HLG-185-42B driver that can run up to 6 strings of 12. In other words, the driver has to be designed to run the number of LEDs in your array or it won't work... or worse, burn out your LEDs or driver.

With that being said... What driver are you using? How many LEDs are you running total? What type/wattage are the LEDs?

 

^ Thats just what I was going to say

 

I already own 2 60-48P's. All the forward current info is in the array pic. It can be done, has been done but the only instructions I've seen aren't clear on adjusting the driver. They do use a 5W 1ohm resistor on each string. It's the driver adjustment that is stumping me.

 

Another point of note... the wizard you used suggested using 1 ohm resistors because you specified a constant forward voltage of 36V and a desired current of 700mA. However, the main purpose of the LED driver is to provide constant current to the LED array by constantly adjusting its forward voltage. Regardless of the driver and LED combination you choose, you will not need to incorporate resistors (except for future current measurement purposes but that is beyond the scope of this post).

Reviewing the numbers on your wizard, you are overdriving your driver. You specified 3.0V for the diode forward voltage. Using this number, notice that the total current draw for the array is 1400mA (or 1.4A) but the ELN-60-48D driver is only rated for 1.2A. However, most Cree LED's operate on a forward voltage of 3.2-3.9 volts and a recommended current of 750-800mA, further increasing the power draw on the driver to 1.5A. Bottom line... The ELN60-48D can't handle 24 LED's at the current needed to get the most light from the diode. If you want to lower your light output, it can be done by adjusting your current to 600mA. Again, you won't need the resistors.... that's what the driver is for.

ReefLEDLights has some good articles on these calculations and on adjusting your driver. I would highly recommend browsing through their resources. Here's a link: Driver FAQ’s « « ReefLEDLights | LED Aquarium Lighting ReefLEDLights | LED Aquarium Lighting

EDIT: I just reviewed the page on ReefLEDLights.com about parallel strings and they have some diagrams for doing what I mentioned above... setting the current to 600mA on two parallel strings of 12. However, this still depends on the type of LED you are using. Here's the link: Wiring Diagrams « « ReefLEDLights | LED Aquarium Lighting ReefLEDLights | LED Aquarium Lighting

 

Thank you for the Driver FAQ link. I'd never looked there. But I was aware of the other link.

So since the two 48P drivers I own are currently driving both xpe and xpg It would be correct to say that I would adjust the output for two parallel strings to 700mA and use 5W 1ohm resistors and 1000mA fuses?

The drivers they use are the d's and they are controlling dim with a pot. Another question I have is can dim be controlled with with PWM when the LED's are in parallel.

Also they do not show how to adjust the SVR when the LED's are in parallel. I am familiar with doing this in a series but how would that way work when making the adjustments to parallel strings?