What happens if.....

[donb]

OK, here is what I (think) I have learned so far in the last couple weeks and I am trying to wrap my head around where I am at (OK I know I am in Lincoln, NE, once described by the joker at the Denver Post as the sewer drain of the US, but I am talking LEDs and electronics here)

 

1) If you have LEDs with a forward voltage of 3v and a 48v power supply should support up to 14/15 per series.

 

2) If these LEDs are said to be 3v @ 700ma then you need a 700ma driver (or greater but the LEDs may have a maximum as well as recommended level) for each series.

 

3) If the LEDs have a wattage of 3w per, then 180w power supply should handle up to ~48 total LEDs (48 x 3 = 144 = 80% of 180)

 

Q1) OK, is any of this right?

 

Q2) Where does the amperage of the power supply play into this? The power supply in question is 180w, 48v, and 3.75a. Am I correct in thinking the amperage of the drivers totaled up needs to be less than the amperage of the power supply?

 

Q3) What if the amperage of the power supply is close or a little under (if that info is correct) the total of the drivers? Do things sizzle? LEDs not fire with no harm? Am I anywhere close with any of this?

 

Thanks

Don

 

Oh yeah, if you know of any good references for this basic info, could you point me to it?

[Milad LEDGroupBuy.com]

1. Correct but its closer to 14 because there is some overhead usually

2. You need 700mA or less. Anything more will blow the LEDs

3. Incorrect, you base it on the voltage not the wattage (look at question 1)

 

Amperage of power supply if you are using LDD + power supply comes into play when you are putting multiple LDDs on each power supply. So for instance if you have 5 1000mA LDDs then you need at least a 5000mA power supply (usually you want a bit more).

 

If the amperage isnt enough then the LEDs wont be running at full steam. Our power supplies that we carry suggest a 80% load so 80% of the total at peak and you will be fine.

[donb]

Thanks for the clarification.

[jedimasterben]

Amperage of power supply if you are using LDD + power supply comes into play when you are putting multiple LDDs on each power supply. So for instance if you have 5 1000mA LDDs then you need at least a 5000mA power supply (usually you want a bit more).

No, this is the part where you base it on wattage.

 

You can have 10x 1A LDD on a 48v power supply that gives 2A as long as you aren't exceeding the wattage. The LDD convert excess voltage into drive current, so if you have two LEDs on each of those 1A drivers, they'll be using around 6.2v, the LDD will give 6.2 and use around 3v itself, so it will convert 38.8v into current, pulling only ~192mA from the power supply instead of the full 1A.

 

The LEDs would be using 62w total (3.1v x 1A = 3.1w x 2 per driver = 6.2w x 10 total drivers = 62w), so the power supply would need to be ~75w minimum output, which would only be ~1.56A

[donb]

Thanks for the input Ben, will chew this over and see what else I can over-think misunderstand

[welight]

A simple way to think about this is if your using an AC source then the outer components dictate power and the inner determine drive

ie leds and AC source need power matching while the LDD determine drive