@L0wbob2017 I dont get really first part of message,are you saying that I dont need power on that zalman? It can cool it passive?.I have this ac adapter.
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Fot second part I understand what you sayin'.. I have spare angelina reflector maybe that could help a little?
The thing i was saying is, that you could do a testrun at 55W for the COB and look how long it takes to get the heatsink warm or hot.( needs to be as long as it would be turned on so 18 hours of testing. Visit the light every 30 minutes and check temp)
If it only gets as warm as your hand without a fan i dont think you will need any fan at all but if it gets hot ( you cant touch it anymore without burning your fingers ) you need a fan.
Also the "rule" is, the cooler a COB, the more light you get out of it with the same wattage and the longer the lifetime of the COB will be.
For the second part i am going to explain it like this:
- COB without Reflector/Lense
- higher coverange, lower intensity
- COB with Reflector/Lense
- lower coverage, higher intensity.
- COB with high distance to the plants
- higher coverage, lower intensity
- COB with low distance to the plants
- lower coverage, higher intensity
A COB without a reflector/lense mostly has a "beaming angle" of 120-130°.
Calculation of the coverage circle radius:
(Radius of the coverage circle) = (distance to the plants ) x ( tan ( ["beaming angle"/2] ) )
If you install a 90° reflector it means "for every cm/inch of distance from the COB to the plants, the radius of the coverage circle increases by the same amount (cm/inch)."
This means at a distance of for example 50cm the radius of your coverage circle is also 50 cm.
With a beaming angle of 120° and a distance of 50 cm the radius of your coverage circle would be about 86,6 cm
With a beaming angle of 130° and a distance of 50 cm the radius of the coverage circle would be about 107,2 cm.
The thing you are aiming for is the balanced value where you cover everything you need and be as intense as possible to get the most out of the coverage which depends on your growroom-setup and the COB/heatsink/reflector/lense combination.
I found it mostly to be at a distance of 50-70 cm using a 90° reflector.