In this video, I play around with some COB LED Panels:
Looking into adding some workshop lighting, I evaluated three kinds of COB LED Panels.
This is the first part in a series on COB LED lighting. Once I’ve identified the properties of the panels and figured out how much current I can safely drive them at, I’m going to end up building a raspberry pi controlled lab lighting system. Look for that blog post in the future!
About the panels I tested
The panels I evaluated are:
1) 10 watt
2) 70 watt
3) 200 watt (yes, really, 200 watts)
You can find them all on eBay as of early 2019, for quite reasonable prices, from China. Typically there are cool white and warm white versions of the panels available. I chose to use the warm white versions because I find that particular lighting less harsh than cool white. Some properties of these panels:
1) They operate off of approximately 12 volts. I say approximately, because you typically want to drive them with a constant current, not a constant voltage. So you pick the current, and the voltage works out to whatever it works out to be.
2) There is no built-in current limiting. This means that you will typically have to limit the current yourself, either via a constant-current regulator (best) or via a voltage-dropping resistor (easy, but suboptimal).
I used a Mastech dual 30 volt x 10 amp power supply. For the big panel, I put the dual supply in parallel mode, for 20 amps of current-handling capability. I tried to test each panel at about a half-dozen points over it’s usable range. I attached a termocouple to the back of the panel using some Kapton tape, and recorded the temperature at each test point. My primary concern in these tests was to determine the maximum wattage at a reasonable temperature. It’s my plan to make up some 3D printed mounts, and I don’t want my printed mount to fail under excessive temperature. I also want to avoid creating any fire hazards.
The results are summarized in the tables below:
10 watt panel
70 watt panel
200 watt panel
So what does it take to kill a panel?
All of the panels survived at their claimed wattage ratings, so I decided to see what it would take to damage or destroy the panels. I found that they failed when they reached 170 degrees Celsius or above. The 200 watt panel in particular started giving off some smoke prior to failure, and then failed outright at 180 degrees Celsius. I was giving it approximately 300 watts of power at the time of failure.