Hello Everyone!!! I would really appreciate your help fingering something out I think there might be some common math here that I am missing or not seeing.
Today I am working on a light from China that has 25 x 10 watt RGB LEDs on it, controlled by a microcontroller. It came with 2 bad power supplies from a previous repair attempt. Troubleshooting the device with a little walwart 12 volt / 1 amp I can get half of the LEDs to light Red, Blue, or Green using the microcontroller. Cool. However, when it hits the color White, it locks up. Obviously this is because you need all three colored LEDs on at the same time (RGB) to produce the color White, and this increased draw is simply too much for the 1 amp power supply and controller (and 4 fans! hehe). But it is great for testing.
Here's some math I think I can figure out - 25 X 10 watts = 250 watts (per color) 250 watts X 3 colors = 750 watts
4 fans, figure 6 watts? Sub Total = 756 watts Microcontroller = meh. let's just say 1 watt Sub Total 757 Watts
Let's set that 757 Watts aside for now.
The power supply for this unit has 2 (actually 3) outputs. 12 volts @ 6 amps and 24 volts @ 3 amps (the third output is 400v at .5 amp (note the decimal). - What!) . They have this light connected to what is marked 12 Volts (@ 6 amps)
Looking at the capacitors on the LED driver boards and microcontroller, they are rated for 35 volts. They use Surface Mount voltage regulators - not sure I can confirm those - The microcontroller board says 24 volts... However, the manufacturer says it should be run at 12 Volts.
During my testing, I worked up the courage to connect this up to my computer's power supply, which is what? 12 volts at around 40 amps?? Anyway, finally that was enough power for the light to hit the Color White and not lock up. Slowly, one at a time, I added one LED back into the the parallel chain of power. Slowly this added more and more current draw to the power supply... This made my test wires heat up.. My cheap little alligator clip wire... stinky. So I disconnected and have not reconnected since.
That's the background.
My question here is I feel it would be more efficient to run this light at 24 volts but this is against what the manufacturer says. Do they really even know, is another question all together because of other issues I've found with the power supply labeling.
Where I am not clear on is obviously if the LED driver boards are rated for 24 volts. To resolve this I need to look up the numbers on the SMT things, assuming I can even read them and they are labeled. The microcontroller board says 24 volts, so I am not too concerned about that except the 12 volt fans that are connected, I did not notice any regulators near the plugs.
During my testing of 12 volts in, I was seeing 4.8 volts out on the fan connectors.
So that's it, I guess, in a nutshell. lol
Am I right? If I run this light at 24 volts, do I only need 3 amps as opposed to 12 volts and 6 amps?
Is 6 amps even enough? Does the math work out? Meaning is 6 amps @ 12 volts = 756 Watts?
Would 24 volts @ 3 amps = 756 Watts and be easier on my little tiny alligator clip wires?
Originally I thought there was a short somewhere in one of the colors (and there still may!!), but I think I might be able to rule that out because running each color individually does not make the test wires warm. By the way, I only got 12 LEDs connected before I noticed the wires getting hot. Could there really still be a short somewhere?
Amps, voltage, and capacitors scare me and there are plenty here.
What caused the power supplies to go bad? During my testing of the LED boards, the capacitors would store the charges they had when powered up, unless the microcontroller set a bit that 'turned on' that LED. Touching the power wires together when no power was applied would produce a spark and a pop (12 volts at ?? amps). It is my theory that enough of these drivers with stored up power in parallel add up to a pretty big punch of power. ?? amps x 25 = ouch! Fry power supply. What I'd like to see is some super dooper (duper?) diode in line somewhere or something to take that hit and drain it right rather than feed it back to whatever unpleasantly grounds it........
Currently, I have a 19.5 volt @ 3.3 amp power supply (laptop charger) connected. This is the closest I can get to 24 volts. I am afraid to turn it on without "talking" it over with you all first.
I'd like to attach pictures, it is easier to imagine that way. There's one picture.
Thank you for reading and not deleting! I am stumped here. :)