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Howdy! I’m trying to make a DIY grow light out of LEDs but I really wanna make sure it’s safe so that I can leave it on unattended.

I bought a 12v LED strip but unfortunately there doesn’t seem to be a data sheet for it available online. Each segment has 9 LEDs, 3 RGB 5050s, one clear white 2835, and one warm light 2835. I wanted to know how much current the LEDs draw so I hooked it up to a variable power supply to monitor the amperage of each line on a strip 12 segments long.

The red, green, and blue lines each drew about 165 mA and the two white lines drew 280 mA. Dividing that by 36 LEDs per line, it seems that each LED draws either 4.6mA or 7.8mA, depending on the type of LED.

I’m wanting to connect these lines to a 12v, 10A power supply and control them with Arduino PWM activating 5 MOSFET transistors. The light itself would have 16 strips wired in parallel that are each 8 segments long. In total this would make 128 segments and each color line would contain 384 LEDs.

The full brightness would have the two white lines energized %100, the red line energized %60, the blue line energized %30, and the green line energized %10. I think that would mean 768 white LEDs at 7.8mA each, 384 red LEDs at 2.76mA each, 384 blue LEDs at 1.38mA each, and 384 green LEDs at 0.46mA each. In total that should add up to a total of 7.58A at full power.

The current ended up being quite a bit higher than I anticipated going into this and I don’t really know anyone who has this kind of experience with electronics so I wanted to get feedback before proceeding. I still want to make a DIY solution so I can have full control over the lights to experiment with what type of light plants crave but I really want it to be safe.

Would a setup like this work if I had the LEDs mounted to a heat sink/fan? Would switching to 24v light strips allow me to get the same wattage/brightness at half the amperage so it’s safer? I’m a semiconductor tool technician and I’m doing this project to learn more so any input would be really appreciated

You really must make a schematic diagram for your proposed setup and show it here. Otherwise you will lose track of what you are doing. I've made somewhat similar setups for custom colour microscope illumination and it's really not all that difficult.