LED Growth Light

Looking into hydroponics, vertical hydroponics, or vertical farming in general, a common problem is the light source: you need extra light unless the plants are directly at a window.

While a complete system would be nice to have, I wanted to start as small as possible which means to skip all the water stuff and use the existing plants we have. The plants we have look sad and are neglected quite a bit, so it’s a perfect specimen to “fix”. All I needed was a light source, and I found one:

Bottom of the LED light
Top with the constant current driver

For about $30 that was hard to beat: no fan and thus no noise, not too big but not too small, plenty LEDs, and should be bright enough to make a difference.

I was pleased when I got it! But not all is perfect:

  • The sticker on the aluminium plate claims “2x10W”. Not sure what it means. The LEDs are organized in 9 parallel rows of 25 LEDs each, and the LEDs can either handle 150mA (Samsung LM281B1 can handle that) or they are getting about 70mA as the driver implies. In no way I can split 9 rows by 2.
  • The LED driver is 50-80V 600mA constant current. The board inside is plastic dipped.
  • Voltage seems to be around 55V (measured at the LEDs when in use). At 600mA that would be 33W. That quite a bit more than “2x10W”.
  • The LED driver gets quite warm (60°C I’d say), but the aluminium plate gets slightly warm. Nice. I expect no heat problems for the LEDs.
  • The light is…bright. More than I expected.
  • The one UV and one IR LED…I wonder if they make a difference.
  • When you try to photograph it, it flickers a lot though:
Recording this lamp is not fun

So the quick fix is to get a new LED driver. I hope that fixes the flicker problem and maybe it gets less hot too. The 600mA might be at the brightness peak only to drop to 0mA when the LEDs are off, so the average might be more at 380mA. Let’s see how those LEDs handle 500mA from the new driver: It would be about 56mA/LED which would be well within the typical 60mA for those type of LEDs.

2022-04-08 update: Got a Mean Well APC-35-500 (up to 70V, 500mA) and while the total brightness went slightly down from 3500 to 3000 lx (measured via physbox app), there’s zero flicker.

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