LED Efficiency?

[orangesabc123]

How can amperage and voltage be manipulated to increase/decrease led efficiency?

Do they have to be moved up/down in tandem?

Is one a function of the other?

 

[AquariusPanta]

The cooler the current, the higher the efficiency.

 

[gk skunky]

Yes they are. Even though you didn't mention a key part of that equation is resistance. Easiest way to describe is a water line. Amperage would be the amount or volume of water moved through at a given time, voltage would be the pressure behind that volume of flowing water, And resistance in this case more of a constant such as the size of pipe. To get higher voltage will equate to added resistance in the line. Think if the pipe is the same size and more pressure is applied there is more resistance as a result. Similar to the opposite like putting your thumb over a waterhose and it increases the stream pressure even though the actual line pressure was not changed from the source. So voltage resistance are proportional. Amperage as well is proportionate. You flow through a pipe designed for 2 gal per minute but try to force 10 gal per minute you will build resistance. Resistance equals heat. Heat means lower efficiency and loss of power not being put to work.

 

[orangesabc123]

The cooler the current, the higher the efficiency.

Yes, this I know.

When I look at drivers for leds they seem to come in only predesignated amperages (.35, .5, .7, 1.2) are those the only options out there then you just vary the voltage or something?

The led spreadsheet thread shows everything in relation to amperage so I'm just trying to get some context on how LEDS are powered.

 

[orangesabc123]

Yes they are. Even though you didn't mention a key part of that equation is resistance. Easiest way to describe is a water line. Amperage would be the amount or volume of water moved through at a given time, voltage would be the pressure behind that volume of flowing water, And resistance in this case more of a constant such as the size of pipe. To get higher voltage will equate to added resistance in the line. Think if the pipe is the same size and more pressure is applied there is more resistance as a result. Similar to the opposite like putting your thumb over a waterhose and it increases the stream pressure even though the actual line pressure was not changed from the source. So voltage resistance are proportional. Amperage as well is proportionate. You flow through a pipe designed for 2 gal per minute but try to force 10 gal per minute you will build resistance. Resistance equals heat. Heat means lower efficiency and loss of power not being put to work.

So do you want higher amperages and lower voltages or a balance?

 

[gk skunky]

So do you want higher amperages and lower voltages or a balance?

Low amps low volts. Why guys are running 3590s in the 36v VERSUS 72v variety at 700mA.

I.e. You want a high output cob (large water pipe) with low voltage driven at low current. Think of efficiency in this sense as the ability to free flow. You just have to minimize the resistive properties of the system. I hope I explained that right and made sense to anyone other than myself.


Though there is definitely a balance especially when building a lamp. Because the more efficient you go the higher you drive your cost.

 

[bicit]

So do you want higher amperages and lower voltages or a balance?

I think high voltage low amperage is better. Purely conjecture on my part though.

 

[orangesabc123]

Low amps low volts. Why guys are running 3590s in the 36v VERSUS 72v variety at 700mA.

I.e. You want a high output cob (large water pipe) with low voltage driven at low current. Think of efficiency in this sense as the ability to free flow. You just have to minimize the resistive properties of the system. I hope I explained that right and made sense to anyone other than myself.

Well I'm going to be doing a rather small panel and I want to mix/spread the leds evenly with lower wattages. That way I can get a good even spectrum and no hotspots.

In the LED efficiency spreadsheet thread it shows that a vero10 or cree cxb1304 will be about 40% efficient and put out 6 watts at .25 amps and 25 volts. I'm not sure if that's the best I can do as that thread has tons of holes and inconsistencies and I have no idea how leds work atm. (I'm not even sure if you can run at .25 amps because the lowest I saw was .35a driver on the site I checked out.)

 

[bicit]

Low amps low volts. Why guys are running 3590s in the 36v VERSUS 72v variety at 700mA.

I.e. You want a high output cob (large water pipe) with low voltage driven at low current. Think of efficiency in this sense as the ability to free flow. You just have to minimize the resistive properties of the system. I hope I explained that right and made sense to anyone other than myself.

Well those aren't directly comparable. The 72v version will be twice as powerful @50w vs 25w for the 36v version. If you look at this chart provided by supraSPL at the same power displacement the 72v version is 0.01% more efficient.

 

[gk skunky]

How big of an area? What types of yields are you after? Things like that. That info will give people a better idea for helping you.

 

[gk skunky]

Well those aren't directly comparable. The 72v version will be twice as powerful @50w vs 25w for the 36v version. If you look at this chart provided by supraSPL at the same power displacement the 72v version is 0.01% more efficient.

View attachment 3404405

Yeah. But look at the photon flux per watt. You get more with low voltage for the reasons I outlined with the water pipe analogy.

 

[bicit]

Yeah. But look at the photon flux per watt. You get more with low voltage for the reasons I outlined with the water pipe analogy.

Truth be told, I have a hard time believing that anyone would notice a .01% difference. Considering the numbers are identical in all other instances

 

[orangesabc123]

How big of an area? What types of yields are you after? Things like that. That info will give people a better idea for helping you.

Space is going to be a large pc/server tower, will probably only be 1.5sqft~ by 2ft height. So, yea, stupidly small.

Was thinking 6x 6watt bulbs, half 2700k, half 4000k.

 

[gk skunky]

Honestly I am not sure I would do anything that small with LEDs. First thought I'd think just use cfls. I feel good leds might be too intense for that height. That or issues with coverage from light source obstruction. Though I'm sure someone else may be better to answer that.

 

[orangesabc123]

Honestly I am not sure I would do anything that small with LEDs. First thought I'd think just use cfls. I feel good leds might be too intense for that height. That or issues with coverage from light source obstruction. Though I'm sure someone else may be better to answer that.

Not really concerned.

Would really just like to know more about efficiency and the voltage/amperage relation.

I personally hate cfls...I would go back to using my hps before I touched a cfl.

#irrationalhatred

 

[AquariusPanta]

Not really concerned.

Would really just like to know more about efficiency and the voltage/amperage relation.

I personally hate cfls...I would go back to using my hps before I touched a cfl.

#irrationalhatred

All you need to know is that COBS driven at lower amps tend to result in higher efficiency but lower total flux output, meaning less photons and lumens. If you are familiar with lumens per watt, then you can expect lm/W to be higher at lower currents.

Also, most COBS carry a general voltage range, meaning they can only be driven only so high before melting and only so low before becoming pointless (what's the point of driving a $100 COB at 100mA if it only puts out 8 watts?).

So without dumbing yourself down any further with this inquiry, just understand that the middle ground is the best place to be when unsure of your surrounding and in this case, being a complete newb.

And if you don't get it by now, then you should either a.) give up on this quest OR b.) research until you come up with a self-revealed answer.

 

[gk skunky]

Exactly and to expand on what he said and general consensus. Drive too soft=cost a small fortune. Drive too hard=premature death. Need to define your middle ground.

 

[SupraSPL]

Space is going to be a large pc/server tower, will probably only be 1.5sqft~ by 2ft height. So, yea, stupidly small.

Was thinking 6x 6watt bulbs, half 2700k, half 4000k.

Here is an example build for your space:
(4) CXB1816 3K Q2 $52 (also available in 4K)
(2) 280mA, 80V drivers $6

Each CXB1816 would dissipate 10W @ 50% efficiency. That would give you 13.3 PAR W/ft² or 665 PPFD average, an average yield might be 1.5 zips each cycle. Driver efficiency 89-90%. The only downside, wondering how long those drivers would take to get here?



You could get even higher efficiency if you are focused on heat OR you could get it done cheaper using Veros if you are trying to minimize cost.
6) Vero10 4K $26
(3)280mA, 80V drivers $6

Each Vero10 would dissipate 7W @ 41% efficiency. That would give you 11.5 PAR W/ft² or 568 PPFD average.

 

[SupraSPL]

Would really just like to know more about efficiency and the voltage/amperage relation.

Regarding white/blue LEDs, As you increase the current flow through the LED, the efficiency decreases significantly (current droop) and the voltage increases somewhat. As the LED and heatsink warm up, efficiency decreases slightly (temp droop) and voltage decreases very slightly.

After everything is temp stabilized, you would arrive at something close to what our efficiency sheets are showing. The sheets are assuming an LED junction temp (Tj) of 50C. When the LEDs are running soft and mounted on a large heatsink, junction temp may be only a few degrees above ambient ~30C. When they are running medium to hard, but sufficiently cooled you might get Tj 60C.

 

[alesh]

Not really concerned.

Would really just like to know more about efficiency and the voltage/amperage relation.

I personally hate cfls...I would go back to using my hps before I touched a cfl.

#irrationalhatred

Current is function of voltage.

The softer and cooler you run LEDs the more efficient they are. Simple as that.