25fV COB?

Is there any COBs out there you know of with a forward voltage of around 25? Or at least that 4 of would fit on an HLG-240H-C2100B? I've got two lying around.

I was originally planning on doing a build with 4 Photon Fantom Wavy Boards(36v) and 4 Vero29SE's(36v) all at 2100mA using 2x HLG-320H-C2100Bs but the price still hasn't come down much on them and if I can't figure out a COB I can fit 4 of on HLG-240, then I may just do 6 Photon Boards (3 on each HLG-240H-C2100B) and say fuck it.

I think 36v is the lowest the good ones go. You could run 3 per driver

Hmm! An HLG-240H-C2100 delivers up to 119vdc, so 29,75v per COB if you want 4 COB's.
Bridgelux's Vero18 "D" is for example a 29v COB rated with 1050mA nom. and 2100mA max., 155lm/w @1050mA and 128lm/w at 2100mA.
I would use 8 Vero18d per driver and connect 4 of them in series 2 times parallel(4s2p)so that each COB would get 1050mA. Would be a 240-260w light with ~153lm/w in 3500°k/CRI80 and ~2,2μMol/j effiency(2,0μMol/j system eff.).

What about just using 48v to 52v cobs and using half as many ? I think one of the hlg boards like maybe the hlg120 is 24v could use those

Randomblame said:

Hmm! An HLG-240H-C2100 delivers up to 119vdc, so 29,75v per COB if you want 4 COB's.
Bridgelux's Vero18 "D" is for example a 29v COB rated with 1050mA nom. and 2100mA max., 155lm/w @1050mA and 128lm/w at 2100mA.
I would use 8 Vero18d per driver and connect 4 of them in series 2 times parallel(4s2p)so that each COB would get 1050mA. Would be a 240-260w light with ~153lm/w in 3500°k/CRI80 and ~2,2μMol/j effiency(2,0μMol/j system eff.).

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And a fuck ton of money in heatsinks. but that's really a great solution if I didn't have to get so many sinks.

Aunt Bob said:

What about just using 48v to 52v cobs and using half as many ? I think one of the hlg boards like maybe the hlg120 is 24v could use those

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Cause unfortunately they're sold out everywhere.

Airwalker16 said:

Cause unfortunately they're sold out everywhere.

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Cobkits has the CMX22 Gen3's in stock and the Citi gen6's in stock so.. I would try there.. Cobkits.com

I'll second the recommendation for QB120s. Pretty sure @Stephenj37826 said they'll be getting more stock in soon? Could be misremembering though.

Airwalker16 said:

And a fuck ton of money in heatsinks. but that's really a great solution if I didn't have to get so many sinks.

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You could use an alu-sheet and add some c-channels on the backside to get something like this:


I've used it former with 6 COB's and now it's the base for my 160w test light(see signature).

It's a 600x 350x 2mm aluminum sheet + eight 20x 20x 2mm c-channels glued on the backside(with cheap thermal tape, e3ay).
With the full 150w's it reach thermal equillibrium after ~3h and max. temps was 48°C with a slightly breeze inside the chamber(exaust/surrounding fans). There is no fan on the backside!

A good rule of thumb is to use ~50-55cm² surface area per watt power consumption for passive cooling. With active cooling it's only 20cm²/w.

You could also use Samsungs F-(23v) or Bridgelux EBgen.2(19,5v) strips. They are cheap(~7-8$, digikey, arrow) and more efficient like Blux Vero18 COB's. 12 EBgen.2, 6 in series, 2 times parallel(6s2p) means 1050mA per strip and ~170lm/w effiency with 3500°k. That's +17lm/w or 12,25% more with strips!