COB light question


#1

So this seems to good to be true … 6 bucks for a true 50 watt LED and it’s driverless. What am I missing? It sounds like one of these for every square foot amd you’re good to go. Can’t be right …


#2

It looks like it has a decent color temperature, though that is stated as two different temps, The question says somebody actually measured the watts at 50+. Now all you don’t know is how efficient it is. They never once mention lumens. Going for 180 or more lumens per watt is why people use COBs. I bet this one is nothing like that. Remember, HPS runs about 133 lumens per watt and some LEDs have only beaten that in the last few years, On another thread, somebody tried a driverless COB. I’m not sure it was the same one, but that one did not have very high efficiency.

Worth getting one and trying to measure the output, though. Still needs a good heat sink.


#3

Those aren’t cob light, well they are but it’s the cgip if you are building your own


#4

When you get into diy leds the led cost itself is only a small portion of total cost. As already noted on this forum, those driverless cobs put out a small amount of light and a lot of heat. Which is a sign of poor efficiency as @1BigFella pointed out. Due to the size of components used we’re assuming a lot of that efficiency loss comes from the ac to dc power conversion, but there’s also a lot to be said about the led efficiency too. So it’s definitely not going to be the same amount of light as the 40 or 50 watt cobs you see the rest of using on our diy builds.

Long story short, for what you’ll spend on heatsinks trying to make those work you’ll be better off just buying a little better cobs and separate driver in my opinion. You can get citi 1212’s, vero 18’s, and I believe an option from luminous for around $10 each. A $46 driver can run up to 6 of them at around 30 Watts, or 5 at 40 watts and either will be plenty for 1 per square foot. The heatsink cost will still be there, just as wire, hardware, and thermal compound. But you’ll have a kick ass light instead of one that leaves a lot to be desired.


#5

Alright, I appreciate the feedback. I figured they were too good to be true.

Wanting to up my game during flowering so just looking around.


#6

What are you already working with as far as space and lights? And what’s the budget?


#7

@dbrn32 2’×4’ and a collection of fluorescent and LED shop and household lights.

I’d spend $100 to $150 and I really don’t want to draw more than 300 to 400 watts. Indoors for me is now mostly seed production and vegging.


#8

That would be tough to do without a little more in the budget as far as cobs go, mainly because of heatsink costs. You could go to like 4 50 Watt cobs for probably $250ish.

Do you have access to any cheap/free aluminum plate or bar stock? Not sure if you’ve seen what @Myfriendis410 or @BIGE have done with bridgelux led strips? But you can usually configure them to get to about $1 per watt. 100-150 Watts of them would be about ideal to veg that space I would think.


#9

Lots of people sell cheap heat sinks on ebay, but they mostly are too small. It is possible to mount your COB on a few square inches of 1/4" copper plate and then attach two of the small heat sinks to the other side of the copper plate. But once you’ve paid for the copper and heat sinks you’re getting up to the cost of pin heat sinks.

I actually have some 2 inch bar stock I was thinking of bolting together to make a big heat sink. I’m not sure it will be much cheaper, though. It would be nice it somebody would sell bigger extrusion pieces on ebay. The custom heat sink shops want an unreasonable amount of money for bigger pieces, though aluminum scrap sells for about $1 per pound.


#10

The biggest problem with the driverless COBs is the light is only about 70% as good as a decent LED light. I’m testing a 300 watt setup with 50 watt full spectrum driverless COBs on my autos and I have the light very close.


#11

Looks like the Chinese have figured out “COBs” are the hot item, so they put a bunch of cheap not-so-great surface mount LEDs on a board and throw it on ebay, amazon. or whatever. The problem is those LEDs are no better than HPS, so you need more of them and more heat sink. (And more electricity for years and years!)

Driverless COBs are of course not a real thing. The driver is right there on the board next to the LEDs. It has no inductors, so it is not a real switcher. It probably uses the same method my DIY drivers use: If the LED string uses about 150 volts or more, you can just use direct conversion of AC to DC and drive the LEDs through a current regulator. But I’m doing that with state-of-the-art COBs from BridgeLux, not Brand X COBs.

Nice idea, though. Too bad nobody does it with good COBs, but maybe they will.


#12

I can scrounge whatever aluminum I might need. But it’s looking like the easiest thing for me is just to grab a Mars Hydro or something like it and call it a day.

I appreciate everyone’s insight.


#13

Being completely honest, money in vs power vs light out there’s probably not a lot of difference between these “driverless cobs” and ready to run budget panel off amazon. So I don’t really blame you there.

You can definitely do some really neat things with diy projects and the right components. If you have interest in it, even a small light for seedlings, clones, or supplemental lighting can be fun and a hood way to get your foot in the door.


#14

Making my own lights is definitely an interest. At the moment I have too many other irons in the fire to take on another project.

But let me return to the 6 dollar, 50 true watt cob that started this thread … are you suggesting that 2 or 3 of those would produce results similar to the Mars hydro 300 that draws 130 true watts? Because I can scrounge all the aluminum I want.
@dbrn32


#15

I meant the opposite, you’d probably be better off buying a budget amazon panel. Sorry for the confusion.

You’re going to need aluminum heatsink extrusions for those driverless cobs. Probably decent sized ones too, and some fans. So $6 each turns into $20+ then you need wire, a way to hang them and so on. All for a what seems to lack luster performance.

Most of us going the diy route are doing so to get the very top level performing technology more so than to save money. Ya, it definitely saves money. But it’s more like spending hundreds instead of thousands, instead of spending $50 over $100.

If you have access to aluminum you should look at those bridgelux eb strips. If we can still find gen 1 strips they start at $4 for 280mm length. Watt for watt they’ll put the average blurple fixture to shame. If you can track down some 1/8” aluminum plate or bar stock would be pretty cheap.


#16

Or even an old aluminum frame from a broken sliding glass door! It’s all about square inches of surface area. Doesn’t matter what it was before.