Low power setup / heatsink dimentions

[TiJay]

Introduction

Last year we bought ourselfs some 2nd hand IKEA grow stuff for in the house:
KRYDDA + VÄXER

The growlight has the following specs:
Colortemp.: 4200 K
Light: 900 lumen
Power: 16 W
Ppfd: 100 μmol/m²/s

The area of the KRYDDA is 57x38 cm: 0,21 m²
Ppf: ~23 μmol/s
lm/W: 56 (this includes the drivers inefficiency, so the light is a little more efficient)

The lettuce, basilicum, seedlings for the greenhouse etc. are flourishing underneath it, so last week my girlfriend said she might want some extra light. Ofc. I mentioned that a DIY build is more fun and gives better lm/W.

I said I would make something similar 3x aluminium bar of ~50cm/1,65" buy a driver, some small COB Vero 10 SE 4 on each bar. and run them on ~300 mA.

Then i thought, i can put 2x Vero 18 SE on each bar, run them at ~600 mA. The COBs are more efficient and it's possible to increase current if situation asks for it.

So I was wanted to find the Right Heat Sink for my COB LED, so I started reading the "How to Find the Right Heat Sink for Your COB LED" part of this side.

So I found the formula:
Rh-a = (Tc – Ta)/Pth – RTIM

Vero 18 B run at 600 mA gives ~19,6W -> 20W.
Heating Coefficient H 0,75
Pth = 15 W
Ambient Air (Ta)= 25°C
Maximum Case Temperature (Tc)= 85°C
Thermal Interface Material Resistance (RTIM) = .05°C/W

After my calculations:
Rh-a = (Tc – Ta)/Pth – RTIM
Rh-a = (85 – 25)/15 – 0.05
Rh-a = 3.95 °C/W
If i might want to increase lightning later so i'm doing the calculations for 30W as well: Rh-a = 2.62 °C/W

Next step I went to the magical internet to find myself a suitable, cheap piece of aluminium to cool them passive. And that is were the problems start. Online I find pieces like:
https://www.tme.eu/gb/details/rad-a5723 ... stonecold/ Thermal resistance 2.3K/W
https://www.tme.eu/gb/details/rad-p3698 ... stonecold/ Thermal resistance 2.3K/W

They're both <2.6 °C/W so should work fine.
Because I heard of the rule of the thumb, 17 sq.in for each hW that ment I should come up with a piece with 23x17=391 sq.in, or 2522 cm².
I'll roughly calculate the surface area of the heatsinks and find that they're only 280 cm² and 606 cm². By far not around the 2500 cm².
So i'm guessing those numbers are for forced convection and I have to go for a bar like this:
https://www.tme.eu/gb/details/rad-a5724 ... stonecold/

Now I read some quantum boards/mid-power LEDs getting even higher lm/W then the COBs i'm focusing on now and you can save on the heatsinks. (Still have to dispatch a lot of heat right?) Now I was wondering were to begin investing in these LED strips, and is it a better solution to go for instead of a few Vero 18 SE?

Note:
1. I already bought myself a ELG-150-36A.
2. looking for a light for seedlings/cutlings etc. might want to grow a few peppers indoors too later.
3. Please take a note on the budget, don't want to spend more then €120-130, Driver costs me ~€20, so have like €100 left for lights and heatsink.

Questions..
1. The IKEA light only has a ppf of 23 and the plants love it. Do all plants benefit from the extra ppf or could they burn?
2. Anyone has an alternative heatsink i could use for this? (heatsink is 50% of the total cost of the lamp)
3. Do those mid-power LED COBs have less heat to dispatch then the Vero 18 SE?
4. Were to start if I want to buy a low power LED strip?

[ShowMe]

It might be tough to find a mid-power board to fit the 36v driver. It might be impossible with your budget. Give these a look:
https://www.digikey.com/product-detail/ ... ND/5358457
https://www.digikey.com/product-detail/ ... ND/4966153

The Samsung is probably the better bet, but you should do the math to see if it would be cheaper to sell the driver and get a 20v driver so you can use the cheaper Bridgelux EB strips:
https://www.digikey.com/product-detail/ ... ND/7907664

LG has some builds set up for these strips.

COBs are a different story. You have all kinds of options at 36v. You could run these with that driver and mount them to aluminum bar or channel and adhere heatsinks as needed:
https://www.ebay.com/itm/5x-CITIZEN-58- ... 2366266276

[LEDG]

The new QB132 from HLG is also a 36V board and doesn't require a sink.

[TiJay]

The new QB132 from HLG is also a 36V board and doesn't require a sink.

This is actually exactly what I was looking for. Efficient, nice size, 22,5 x 30cm, not to expensive, 4 of them for ~$130 (+$50 VAT) that makes ~€35 each. When saving bucks from heatsink and frame and very clean and easy to mount.

I already bought myself 6x VERO 18 SE (Arrow) matching my driver (ELG-150-36A) with heatsinks from Kingbrite. Might just finish that light, sell it and go for some of these qb!

[LEDG]

Nice. I’m sure you’ll love the Veros too though.