Vero upgrade project

Hi,

I took a few chinese cheapo cob units and upgraded them with Vero SE 29s. The drivers are 45-70v, 700ma, pwm dimmable, one for each cob making a total of 6 with 3 small fans on another driver. The original chips were mounted to a 1/8" aluminum plate with some thermal tape and ran around 50-60c on full power of 338w from the wall.

For cobs I went with 6 3000k 80cri Cs on one and 6 3000k 90cri C for another. From what I have read the higher cri has been producing better results and I also have the flexibility to mix them if I want to. Each cob has its own driver that uses pwm dimming and ranges from 0 to around 46w max per cob.

I figured that the better chips were going to produce less heat so I stayed with the original aluminum plate and mounted the Veros using some AS5 with the existing drilled holes. Ended up being right as the case temp never gets above 35 and the measurement point on the cobs hits 39-40 using an IR meter. Room ambient stays at 25c with lots of circulation.

While not completely DiY, it does work well and I am pleased with the results.

Couple of questions:

1. pwm dimming - good, bad or ugly? I have read that it is the preferred way to dim LEDs for a number of reasons but nothing specific for growing purposes.

2. are people going overboard with heat transfer? These massive and quite often expensive heatsinks might be overkill when something simple will do. Even with the internal fans off the temperature hit a steady state of 74c which is still well within operating parameters. By not going with anything special I put that money into more cobs, so I was able to go from 8 to 12 in total.

I use pwm dimming, mostly better for on/off, as once you set the intensity it rarely changes. I use pwm to replace my timers for lights. I use the GrowGreen led Controller for pwm service 6-8 channels works with LDD drivers and 185H style drivers. I use both drivers.

I use the active heat sinks with fans and have no temp issues to speak of, beyond normal exhaust fan needs

Is that a pwm signal to the driver rather than pwm to the cobs? From what I have read, the typically used Meanwells use analog dimming by current reduction. Maybe I should have specified current vs pwm dimming. Which is better for growing is what I would like to know.

Yes there are lots of cool things you can do with signalling to adjust timing, intensity, etc and that may be a future project if necessary. I have some far reds and uv I would like to run some tests with to try and pin down what works best.

One thing I will say is that the plants under the 90 cri seem to be happier. Although the 80 cri puts out more lumens on paper, the par readings at the same power usage are within margin of error. Leaf texture looks better and more natural. I have some more Veros coming in so I am going to run a 5/1 and 4/2 80/90 mix to see if makes a difference.

My next project is to take all the old chinese cobs and mount them to a larger sheet of 1/8" aluminum plate that could be easily hung on a wall or open air. The plan is to run them in parallel until there is no significant heat generated similar to the QBs. Cooling is covered with good air circulation since you need it for optimal growth anyhow.