Chinese COBs?

djimb · Mar 24, 2018

I'm planning a new cab in which I'll be using a Mars Hydro LED panel (nominal 300w, actually pulls closer to 150) and I'm trying to decide between screw in led bulbs or a pair of DIY COB lights to supplement it. I was originally set on the bulbs, as building a fixture using 10 15w units seems like it would only cost about $60-80, but I started looking at cheap Chinese COBs and drivers on eBay, and I could conceivably get 10 100w COBs and 3 100w drivers for the same amount or less. This has led me to a few questions:

Does anyone have much experience with these cheap COBs, and could they be reliable running at roughly 33w?

I'm thinking running 3 COBs per driver (wired in parallel?) might be sufficently under powered to be reliable, and two fixtures built like this would leave me with enough spares to replace anything that burns out.

If that configuration does work, would it run cool enough to be able to use similarly cheap passive heatsinks, or would they need fans?

Would it be better to use more COBs at lower wattage?

Would it be better to stick with LED bulbs?

Ideally, in another year or so I'd replace this setup with either better COBs or a CMH (or both?), so this won't be a permanent solution. I'm just trying to keep initial costs on the low end while still getting better results than I've had with the Mars Hydro panel alone.

Thanks!

Koondense · Mar 24, 2018

You're going the right way, the chinese cheap cobs are not good but can be better than household leds when driven softly. I'd suggest around 30-40% of max load.
CMH is obviously much better.

Cheers

DJXX · Mar 24, 2018

djimb said:
I'm planning a new cab in which I'll be using a Mars Hydro LED panel (nominal 300w, actually pulls closer to 150) and I'm trying to decide between screw in led bulbs or a pair of DIY COB lights to supplement it. I was originally set on the bulbs, as building a fixture using 10 15w units seems like it would only cost about $60-80, but I started looking at cheap Chinese COBs and drivers on eBay, and I could conceivably get 10 100w COBs and 3 100w drivers for the same amount or less. This has led me to a few questions:

Does anyone have much experience with these cheap COBs, and could they be reliable running at roughly 33w?

I'm thinking running 3 COBs per driver (wired in parallel?) might be sufficently under powered to be reliable, and two fixtures built like this would leave me with enough spares to replace anything that burns out.

If that configuration does work, would it run cool enough to be able to use similarly cheap passive heatsinks, or would they need fans?

Would it be better to use more COBs at lower wattage?

Would it be better to stick with LED bulbs?

Ideally, in another year or so I'd replace this setup with either better COBs or a CMH (or both?), so this won't be a permanent solution. I'm just trying to keep initial costs on the low end while still getting better results than I've had with the Mars Hydro panel alone.

Thanks!

if you see the pics below these are Bigeye LEDs and they needed some cobs replaced, so i bought the 100 watt chinese cobs and at 7.99 each they do pretty good, if you got the money i would buy Cree CXB3590 at $32, using the same drivers, but at the 7.99 price if you are ok with changing them, those work pretty good, they start goin out a row at a time after bout 2 yrs use....also look on ebay, they have really cheap cob led grow fixtures and verses buy the parts, just buy a fixture already put together....another thing you might check out is DIY Quantum Boards, check out Lapides thread on those, they are pullin some insane yields with those cob strips...and they are pretty simple builds..DJXX

Killkingkong · Mar 26, 2018

I built this light for just over $50 using cheap china cobs, cheap china heatsink and a cheap china 50w driver.

I'd recommend spending the extra money on the LEDs, the cheap (300mmx140mm) heatsink and driver are fine. The cheap one was the first light I made with the cheap $14 heatsinks from china/ebay. The higher quality lights come from digikey. they were made by lumiled, but I wish I saw the samsung ones that are thinner ( you can fit 6 instead of 5 on the heatsink). the samsung ones are 11v, so I would run them 3 series 2 paralell to get to 33v which is in the range i currently use.

DJXX · Mar 26, 2018

sweet cking you out...you are way more advanced than i am...did you ck out Lapides DIY Quantum Boards...not near as cheap as you have done, but really insane yields done with them..DJXX

Killkingkong · Mar 26, 2018

DJXX said:
sweet cking you out...you are way more advanced than i am...did you ck out Lapides DIY Quantum Boards...not near as cheap as you have done, but really insane yields done with them..DJXX

He's how I found out about the strip cob lights. I don't post much anymore, but I keep up with the latest technology and they're way more efficient and spread the light out much better. I just applied what he did to my cheap style. I was mostly using those square LED cobs before, but they put all the light in a single spot. I've tried all kinds of LEDs you can think of, those strips are the best purchase you can make for the money. BTW, the strip lights don't require soldering at all. Either screw or glue them down, then push high quality wires into the slots.

djimb · Mar 26, 2018

Thanks for all the feedback, everyone!

Killkingkong, that looks about like what I was planning on, only I'd split it into two fixtures to hang on either side of the Mars Hydro panel. I was thinking of doing 3-4 per 100w driver. I'll look into those Samsung strips, too.

DJXX, I'll definitely look into the quantums, too. I like the idea of strip LEDs for more even coverage. I've also looked at the Sol Strips that ReikoX is using over in the micro grow forum. Those seem pretty affordable save for the drivers they sell.

Koondense, thanks for the tip about running them light. I figured pushing them at the rated wattage would only burn them out.

bsgospel · Mar 26, 2018

Killkingkong said:
He's how I found out about the strip cob lights. I don't post much anymore, but I keep up with the latest technology and they're way more efficient and spread the light out much better. I just applied what he did to my cheap style. I was mostly using those square LED cobs before, but they put all the light in a single spot. I've tried all kinds of LEDs you can think of, those strips are the best purchase you can make for the money. BTW, the strip lights don't require soldering at all. Either screw or glue them down, then push high quality wires into the slots.

So the cheap chinese panel was ~$50- how much would you estimate the samsung strip panel you show costs? My guess would be ~$120 from what I've been seeing online.

Killkingkong · Mar 26, 2018

bsgospel said:
So the cheap chinese panel was ~$50- how much would you estimate the samsung strip panel you show costs? My guess would be ~$120 from what I've been seeing online.

The last time I bought cheap cobs (~2-3 years ago) a 10 pack cost me $27 free shipping. The samsung quantum board light strips that fit on a 300mm long heatsink cost $8/each and you can fit 6 of them on there, so only $21 more (before shipping cost) for much much better quality and slight spread than cheap cobs or screw in LEDs. However on digikey you get a price break at 10. so you can get 12 light strips for ~$80 (not including shipping) and build 2 of them for ~$120.

Parts List:
LED: https://www.digikey.com/product-det...uctor-inc/SI-B8U051280US/1510-2282-ND/7562240

Heatsink: https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=300+140+heatsink&_sacat=0

Various Wattage Drivers: https://www.ebay.com/itm/10W-20W-30...Supply-85-265V-Constant-Current-/192014536760

End Result:

Closet Light being run at 100w, so I went overkill with fans. I'm overdriving these lights a ton, but the results are great.

PC Light being run at 50w. side fans blowing hot air toward the exhaust.

bsgospel · Mar 26, 2018

*high five* Thanks for sharing! Something in this vein will be my next project. Sorry for hijacking OP. Hope it helped you too!

djimb · Mar 27, 2018

bsgospel said:
*high five* Thanks for sharing! Something in this vein will be my next project. Sorry for hijacking OP. Hope it helped you too!

Don't worry about it! This has all been extremely helpful!

Killkingkong said:
The last time I bought cheap cobs (~2-3 years ago) a 10 pack cost me $27 free shipping. The samsung quantum board light strips that fit on a 300mm long heatsink cost $8/each and you can fit 6 of them on there, so only $21 more (before shipping cost) for much much better quality and slight spread than cheap cobs or screw in LEDs. However on digikey you get a price break at 10. so you can get 12 light strips for ~$80 (not including shipping) and build 2 of them for ~$120.

Parts List:
LED: https://www.digikey.com/product-detail/en/samsung-semiconductor-inc/SI-B8U051280US/1510-2282-ND/7562240

Heatsink: https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=300+140+heatsink&_sacat=0

Various Wattage Drivers: https://www.ebay.com/itm/10W-20W-30W-50W-100W-High-Power-LED-Driver-Power-Supply-85-265V-Constant-Current-/192014536760

Thanks for all of that! I spent some time looking at LED strips today and it looks like they're less expensive per watt than the cheap COBs run at ~30% capacity, with better coverage and probably less concentrated heat.

I found 5 meter strips of 5630 (.5 watt, 120/meter, warm white, 300 watt total) and 7020 (.5-1 watt, 60/meter, cool white, 150 watt total) diodes for $8-$9 per roll.

Assuming these are more reliable than the cheap COBs, I could run them at ~50% capacity and have a much better setup. If they run as cool as the quantum boards seem to, I might not even really need heat sinks.

I'll look at more legitimate sources like digikey and mouser too, but I think this is going to be the way to go.

Thanks again everyone!

warpese · Apr 16, 2018

djimb said:
Don't worry about it! This has all been extremely helpful!

Thanks for all of that! I spent some time looking at LED strips today and it looks like they're less expensive per watt than the cheap COBs run at ~30% capacity, with better coverage and probably less concentrated heat.

I found 5 meter strips of 5630 (.5 watt, 120/meter, warm white, 300 watt total) and 7020 (.5-1 watt, 60/meter, cool white, 150 watt total) diodes for $8-$9 per roll.

Assuming these are more reliable than the cheap COBs, I could run them at ~50% capacity and have a much better setup. If they run as cool as the quantum boards seem to, I might not even really need heat sinks.

I'll look at more legitimate sources like digikey and mouser too, but I think this is going to be the way to go.

Thanks again everyone!

if you go with the smd leds look at the 561c samsung actually probably best 5630 smd.
Please stay away from 9$ roll strips.
this is my 140w fixture

my

djimb · Apr 16, 2018

warpese said:
stay away from 9$ roll strips.

Aw, is that price point too good to be true? Have you experienced issues with reliability? Heat? I figured they couldn't be worse than the cheap COBs, but are they?

Thanks for your input.

warpese · Apr 17, 2018

djimb said:
Aw, is that price point too good to be true? Have you experienced issues with reliability? Heat? I figured they couldn't be worse than the cheap COBs, but are they?

Thanks for your input.

I've never tried these cheap rolls, on average the prices of good LEDs are $5/mt, $/25 roll on alibaba. it's hard for a $9/roll to be powerful and efficient

maybe i would prefer cheap cobs to cheap smds, if you drive them at 30% 40% you will gain more efficiency.

I hope my English is understandable
:tiphat:

Killkingkong · Apr 18, 2018

djimb said:
Aw, is that price point too good to be true? Have you experienced issues with reliability? Heat? I figured they couldn't be worse than the cheap COBs, but are they?

Thanks for your input.

To each their own, you decide what's too good to be true. but you simply won't have nearly as good results compared to name brands like samsung. from some vague research i did I saw about 1/2 the lux (yeah yeah i know lumens isn't for plants, but the comparisons in lux still say very much) from high quality leds compared to cheap ones. if you wanna grow 1 time and burn everything down, cool. if you wanna make something you can use more than once, spend the extra money for the far more production. I fully believe in china as far as common products we use that they have time to cheaply perfect, but as far as LED tech, they're always behind. they don't put money in research and development. samsungs strips meet R&D and cost at a good point.

djimb · Apr 20, 2018

Thanks a lot for your input, I was planning on these being a short term solution for just a couple of rounds, so long term efficiency or reliability weren't especially important. I was just looking to get a little boost until I could afford quality LEDs or a 315w CMH. Now I'm considering a couple small guerilla plots as an alternative, so I may not need the lights anyway.

Thanks again everyone!

Klompen · Sep 10, 2018

Great thread. I recently ordered 700W worth of 50W COBs with built in current regulators(so they can run directly off mains AC voltage). I'll let you know how it goes but for 31 dollars it is hard to beat....

Traveller x · Sep 12, 2018

Can someone explain me the difference between cob Cityzen and Cree?I m going to buy a big quantity of led cob an I want to be sure to buy the right ones.
Thanks

bolder · Sep 12, 2018

different manufacturer. cree has CXB3590 (latest) and CXB3070 (older). citizen the most used one as I see is Citizen CLU048-1212 Gen. 6.
both are excellence.

you can also add Bridgelux Vero 29 Gen 7 and Luminus cxm22 to the list ;-).
now start reading, he he. there's a lot of info. don't go and buy before you spend a couple of hours on research.

As I see from my research, and I'll use that when the switch from MH/HPS arrives, is going with DIY strips (samsung or bridgelux).

you also have and option for quantum boards.

just do yourself a fever and avoid chinese COBs/strips/boards.

good luck.

BombBudPuffa · Sep 12, 2018

Traveller x said:
Can someone explain me the difference between cob Cityzen and Cree?I m going to buy a big quantity of led cob an I want to be sure to buy the right ones.
Thanks

I'm using the Gen 5 citizens. Only paid $10 a piece for them.

https://cobkits.com/product/citizen-clu048-1212-90cri-gen5/

Chinese COBs?

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