Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Hello guys,
Just wondering is it possible to decrease the power consumption of a LED or an array of LEDs all connected together in parallel and supplied by 3V DC without any significant loss in the light intensity/brightness of them?
thanks
Use a switching LED driver.
Hi,
The only way to decrease power consumption in LEDs without affecting the light output is to find LEDs that are more efficient. That is, they put out more light per amp, and/or they have a lower terminal voltage. Either way you get the same light output with less power consumed in the LED itself.
The power consumption of the LED is not the only issue however because sometimes the LEDs are driven from a resistive source. The resistive part of the source dissipates power too so you loose power just because of the way it is being driven. So the idea then is to reduce the resistive part of the driver. This is usually done with a switching voltage regulator set up as a current feedback regulator. This usually (but not always) provides higher efficiency in the overall system. I said usually because this isnt always the case. If the voltage source voltage level is close to the voltage of the LED or LED string, then there may be little or nothing to gain by using a switching regulator. In fact, there are times when using a switcher will actually reduce overall efficiency and this is when the source voltage is already pretty well matched to the LED voltage.
So the first thing to do is analyze the system to see what category your circuit falls under and take the appropriate action. It usually helps to find the most efficient LEDs first unless the lower forward voltage then provides a mismatch between source and LED characteristic voltage.
It almost always helps to run the LED at reduced current too. The efficiency goes up if you run it at 1/2 the nominal rated current, so running two LEDs at the same current as one LED effectively produces more light. The effect isnt super significant however so you may want to do a couple of tests with your actual LEDs to see if it warrants doubling the number of LEDs for a small gain in light output. Another benefit however is very significantly increasing the life of the LED.
Hi dr.power,
How about driving them with AC volatge instead DC, making them to blink at high rate frequencies? for instance at 100Hz, or 1kHz and see what comes up about the power consuming and brightness? Our eyes are not sensitive against such blinks at those frequencies as I know.
A switching LED driver reduces the average current then it also reduces the brightness.
That's only true if you replace the resistor with an inductor.Switching LED driver eliminates the need for current limiting resistor. The average current can stay the same. Switching regulator is more efficient than linear regulator.
Why not simply switch banks of LED's to alter brightness, as he does in the article.
Switching LED driver eliminates the need for current limiting resistor. The average current can stay the same. Switching regulator is more efficient than linear regulator.
I want to decrease the AMP-draw for a constant amount of LED's, So It does not help me if just try to just switch.....
A switching LED driver turns on the LED very brightly for a moment then turns it off for a moment over and over so the average current is enough to produce fairly bright visiblity. It turns on and off so quickly that you see no flickering unless it moves.
When the driver turns on then its voltage drop is low so it wastes very low power. When the driver is off then it wastes no power.
A current-limiting resistor wastes power ALL THE TIME.
Switching LED's in and out alters brightness and current consumption, which is what you're wanting to do - and is what most commercial lights do (it's simple, cheap, and effective). Altering the PWM ratio (if using PWM) will provide the same effect, but in a much more complex way).
Hello,
I second that idea. If you have a lot of LEDs, why not turn some off for lower power. It's the simplest way to do it and it works pretty well if you only need a few set brightness/power levels.