Wiring Parallel LED strings?

[JMcAz7]

I understand how series/parallel works with voltage and current drop, but I have a couple of questions about wiring LEDs in parallel strings.

1.) Why are we adding a resistor inline?

2.) How is resistor and fuse values determined?

I've done a straight ahead linear setup with just 9 LEDS in a series before on a driver, but I'm about the step up my project. Additionally, people are looking to me to help them understand the wiring and I don't want to steer them wrong.

I appreciate the help all. Thanks ahead of time.

 

[SolidState]

I may be able to move you forward. First, I would like to understand why you were told that resistors should be added to the circuit?

Also, you probably should clarify why you would need to create parallel LED strings.

 

[psteeleb]

I understand how series/parallel works with voltage and current drop, but I have a couple of questions about wiring LEDs in parallel strings.

1.) Why are we adding a resistor inline?

2.) How is resistor and fuse values determined?

I've done a straight ahead linear setup with just 9 LEDS in a series before on a driver, but I'm about the step up my project. Additionally, people are looking to me to help them understand the wiring and I don't want to steer them wrong.

I appreciate the help all. Thanks ahead of time.

I ran mine in parallel and did not use either. The ballast I used has a potentiometer, I turned it down all the way and then brought it up to the required levels. I can see where it would still be a good idea to use a set of fuses. I guess if you had an unballanced load you would need to use a resistor but mine had the same number of the same type LEDs on each run.

 

[JMcAz7]

So, here's what I'm working with.

I'm going to be building a setup for my 90G, around 100 LEDs or so. I plan on running 2 large drivers (Meanwell HLG series or similar) with multiple parallel strings. I don't have any specifics yet (I'm still planning), but you get the general idea.

Most of the setups I've seen appear to have a high power resistor in line with the LEDs, in addition to a fuse. I'm trying to understand why.

 

[JMcAz7]

I ran mine in parallel and did not use either. The ballast I used has a potentiometer, I turned it down all the way and then brought it up to the required levels. I can see where it would still be a good idea to use a set of fuses. I guess if you had an unballanced load you would need to use a resistor but mine had the same number of the same type LEDs on each run.

I can see if it's for the sake of balancing the load. That makes sense since the current is dependant on the voltage drop across the string, correct?

 

[psteeleb]

I used this as a guide

http://reefledlights.com/wiring-diagrams/

they also have good pricing

 

[hllywd]

Using info from the same web-site, resistors and fuses explained...

http://reefledlights.com/resistors-and-fuses-in-parallel-strings/

 

[dlp211]

I understand how series/parallel works with voltage and current drop, but I have a couple of questions about wiring LEDs in parallel strings.

1.) Why are we adding a resistor inline?

2.) How is resistor and fuse values determined?

I've done a straight ahead linear setup with just 9 LEDS in a series before on a driver, but I'm about the step up my project. Additionally, people are looking to me to help them understand the wiring and I don't want to steer them wrong.

I appreciate the help all. Thanks ahead of time.

The reason many people put a resistor inline is to easily measure current across the strings with an Digital Multimeter. It is done with a 1ohm 1% 2 or 3 watt resistor. As you know watts = volts*current, so by using a 1ohm resistor V=C.

To determine your fuse value you need to determine what the max current you will drive your LEDs. If a string fails, then it is going to redistribute that current to the other strings, so your fuse should be more then your max current but less then or equal to the max current an LED could handle.

ie: XPE RB has a max current of 1A. You drive at 700mA. Your fuse is 1A. This way if the current ever exceeds 1A your LEDs are protected. Also make sure you get fast acting or quick blow fuses.

I hope this helps.

 

[Jimmy54]

Not using resitors means putting the multimeter inline to measure the current.
The connections with the probes need to be solid. If that circuit gets broken during measuring the string's current, by lifting one of the probes, and then reconnected, the LEDs will probably fry.
With resistors you don't have that problem, and you don't have to switch the driver(s) on and off each time you're going to check the current.

I guess if you had an unballanced load you would need to use a resistor but mine had the same number of the same type LEDs on each run.

And even than, with the same type LEDs, you still can have unbalanced strings and the only way to find out is by checking the current.

 

[kcress]

Resistors?

I strongly suggest you read this thread from the beginning to at least about post #100 where it starts to diverge.

Note the drawing I did in post #39.

It's by far the most concise thread on building and commissioning a parallel build.

It includes all the pre-flight testing you should do to prevent you from writing your own horror story and it shows how you use the resistors.

Remember, in a parallel build you must balance your strings and to to it well and easily you need the resistors.

http://www.reefcentral.com/forums/showthread.php?t=1973462

Learn not to burn --- your LEDs!

 

[skanderson]

resurrecting an old thread with a new question. I plan on running gen 7 vero 13s in a new supplemental led light that I am making. I will be making 5 lights each with 3 of the vero 13s running at 500 mA for about 16 watts ea. I would like to avoid running 3 ldds 500mA drivers for the sake of simplicity so I was considering running the 3 on parallel strings with a 1500mA ldd. do you think I need to run resistors and or fuses in order to do this safely. thanks, steve

 

[oreo57]

resurrecting an old thread with a new question. I plan on running gen 7 vero 13s in a new supplemental led light that I am making. I will be making 5 lights each with 3 of the vero 13s running at 500 mA for about 16 watts ea. I would like to avoid running 3 ldds 500mA drivers for the sake of simplicity so I was considering running the 3 on parallel strings with a 1500mA ldd. do you think I need to run resistors and or fuses in order to do this safely. thanks, steve

AFAICT you'd never run resistors w/ constant current drivers..
The resistor is sort of the "constant current" part of the constant voltage array..


There is a whole "thing" about balancing current across multiple parallel strings but most of the time it doesn't really seem necessary..

Fuses, on th other hand, are cheap protection in the event one chip goes "open" and your 500mA becomes 750ma on the 2 remaining

If for some reason 2 go open.. lat puck gets the 1500mA...

http://mt-system.ru/sites/default/f...n._7_vero_selection_guide_201601114_rev_c.pdf