Is it possible to build a good COB LED light for a grow tent 3x3x5 for under $200.00?

randydj

Well-Known Member
Is it possible to build a good COB LED light for a grow tent 3x3x5 for under $200.00?

I have done a lot of reading here and there does not seem to be a consensus about much in relation to a cheap build that meets anybody’s growing standards. I am so confused. Help!

I am a child of the 60’s and smoked a lot of pot back in the day. Then some career choices had me clean for over 35 years. I have a deteriorating disc in my back with a lot of pain. I do not tolerate opioid type medications and the NSAIDS were destroying my liver and kidneys. My doctor decided I should try Cannabis. Well ok, it works better than the NSAIDS. I am retired on a fixed income and want to grow my own medicine. I live in the San Joaquin Valley of California and it is really hot here in the summer. I can only afford to run a swamp cooler so my best daytime indoor temp is 82°F with 60% RH. I have a small tent 3x3x5 running a top fed deep water culture (5 gallon bucket), 6” hyperFan exhaust with plenty of CFM. I was running my day/night upside down to help with the heat. I have two small cheap Chinese LED fixtures. I started with 8 CFLs but the heat buildup was just too high. Remember my incoming air is already hot. I had to have something fast so that is why the Roleadro LEDs. Fortunately, I had most everything I needed to add CO2 and I programmed an Arduino Uno to inject the CO2 based on cubic foot calculations without letting the tent go over 95°F before turning the exhaust fan back on. I am actually surprised by the results so far. I made a NOOBZ mistake with my genetics as I chose Moby Dick CBD based on the high CBD, expected yield and flavor profile – all good for what I was looking for. I failed to notice that this strain needs a LOT of room to grow. The first clue should have been in the name – MOBY DICK!!!. Here is a picture of Mobina I thought she should have a girl’s name. I think I still have 4 or more weeks to go.


I want to upgrade my lights for my next grow. I have a fixed income. I will not be selling any pot to supplement my medical grow because I will not risk a stint at the cross bar hotel. So please don’t talk about the macro economics of spending more money to save more over the long term. I understand that already. Can a good COB based LED grow light be built for under $200.00? I can scrap together a frame. I want to mount the driver/s outside of the tent. Since vertical space inside the tent is at a premium I don’t think I need lenses or refractors but you tell me.
 
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dandyrandy

Well-Known Member
Maybe. Vero should be dumping the old vero 29's maybe catch a sale. The cheapest way I have seen is using a CPU cooler. 4 would run around $45. 4 cobs of your choice $15 to $45 a piece. Difference being efficiency. Run 4 at 400 watts give or take. Dimmer is nice. Drivers $50 give or take. Probably $250 total. Some people sell nice kits here. I use 16 3590's in ~15 sq feet. Two bars of 8. No lens or reflector.
 

MeGaKiLlErMaN

Well-Known Member
Seeing how the drivers usually are between $60-90 that would be a stretch. Short answer yes you "can" but I wouldn't use this light for anything other than Veg. The point of using these lights is efficiency... not being cheap in the short term. Long term these light more than pay for themselves.


CXB3590DD36V5000K 2 COBS @3.6A ON 5.88 PROFILE HEATSINK
9 SQ.FT. CANOPY 92% EFFICIENT DRIVER @15 CENTS PER KWH
Total power watts at the wall: 298.91
Cobs power watts: 275
Total voltage forward: 76
Total lumens: 38701
Total PAR watts assuming 10% loss: 108
Total PPF: 482.76
PPFD based on canopy area: 577.38
PAR watts per sq.ft.: 12.0
Cob efficiency: 43.44%
Power watts per sq.ft.: 30.56
Voltage forward per cob: 38.22
Lumens per watt: 140.73
Heatsink riser thickness / number of fins / fin's length: 0.27in/14/1.0in
Heatsink area per inch: 260.01 cm^2
Total heat watts: 156
umol/s/W / CRI: 4.47 / 70CRI
Heatsink length passive cooling @120cm^2/heatwatt: 72 inches
Heatsink length active cooling @40cm^2/heatwatt: 24 inches
COB cost dollar per PAR watt: $0.86
Electric cost @12/12 in 30 days: $16.64
Electric cost @18/6 in 30 days: $24.71
Cost per cob: $46.5
Heatsink cost per inch cut: $1.74
Total cobs cost: $93
Total heatsink passive cooling cost: $125
Total heatsink active cooling cost: $41



CXB3590CD36V3500K 2 COBS @3.6A ON 5.88 PROFILE HEATSINK
9 SQ.FT. CANOPY 92% EFFICIENT DRIVER @15 CENTS PER KWH
Total power watts at the wall: 298.91
Cobs power watts: 275
Total voltage forward: 76
Total lumens: 33363
Total PAR watts assuming 10% loss: 93
Total PPF: 432.45
PPFD based on canopy area: 517.21
PAR watts per sq.ft.: 10.33
Cob efficiency: 37.44%
Power watts per sq.ft.: 30.56
Voltage forward per cob: 38.22
Lumens per watt: 121.32
Heatsink riser thickness / number of fins / fin's length: 0.27in/14/1.0in
Heatsink area per inch: 260.01 cm^2
Total heat watts: 172
umol/s/W / CRI: 4.65 / Estimated
Heatsink length passive cooling @120cm^2/heatwatt: 79 inches
Heatsink length active cooling @40cm^2/heatwatt: 26 inches
COB cost dollar per PAR watt: $1.02
Electric cost @12/12 in 30 days: $16.64
Electric cost @18/6 in 30 days: $24.71
Cost per cob: $47.62
Heatsink cost per inch cut: $1.74
Total cobs cost: $95
Total heatsink passive cooling cost: $137
Total heatsink active cooling cost: $45
 

Airwalker16

Well-Known Member
Is it possible to build a good COB LED light for a grow tent 3x3x5 for under $200.00?

I have done a lot of reading here and there does not seem to be a consensus about much in relation to a cheap build that meets anybody’s growing standards. I am so confused. Help!

I am a child of the 60’s and smoked a lot of pot back in the day. Then some career choices had me clean for over 35 years. I have a deteriorating disc in my back with a lot of pain. I do not tolerate opioid type medications and the NSAIDS were destroying my liver and kidneys. My doctor decided I should try Cannabis. Well ok, it works better than the NSAIDS. I am retired on a fixed income and want to grow my own medicine. I live in the San Joaquin Valley of California and it is really hot here in the summer. I can only afford to run a swamp cooler so my best daytime indoor temp is 82°F with 60% RH. I have a small tent 3x3x5 running a top fed deep water culture (5 gallon bucket), 6” hyperFan exhaust with plenty of CFM. I was running my day/night upside down to help with the heat. I have two small cheap Chinese LED fixtures. I started with 8 CFLs but the heat buildup was just too high. Remember my incoming air is already hot. I had to have something fast so that is why the Roleadro LEDs. Fortunately, I had most everything I needed to add CO2 and I programmed an Arduino Uno to inject the CO2 based on cubic foot calculations without letting the tent go over 95°F before turning the exhaust fan back on. I am actually surprised by the results so far. I made a NOOBZ mistake with my genetics as I chose Moby Dick CBD based on the high CBD, expected yield and flavor profile – all good for what I was looking for. I failed to notice that this strain needs a LOT of room to grow. The first clue should have been in the name – MOBY DICK!!!. Here is a picture of Mobina I thought she should have a girl’s name. I think I still have 4 or more weeks to go.


I want to upgrade my lights for my next grow. I have a fixed income. I will not be selling any pot to supplement my medical grow because I will not risk a stint at the cross bar hotel. So please don’t talk about the macro economics of spending more money to save more over the long term. I understand that already. Can a good COB based LED grow light be built for under $200.00? I can scrap together a frame. I want to mount the driver/s outside of the tent. Since vertical space inside the tent is at a premium I don’t think I need lenses or refractors but you tell me.
Roleadro makes a light now using g cree CXA chips.
 

a mongo frog

Well-Known Member
Is it possible to build a good COB LED light for a grow tent 3x3x5 for under $200.00?

I have done a lot of reading here and there does not seem to be a consensus about much in relation to a cheap build that meets anybody’s growing standards. I am so confused. Help!

I am a child of the 60’s and smoked a lot of pot back in the day. Then some career choices had me clean for over 35 years. I have a deteriorating disc in my back with a lot of pain. I do not tolerate opioid type medications and the NSAIDS were destroying my liver and kidneys. My doctor decided I should try Cannabis. Well ok, it works better than the NSAIDS. I am retired on a fixed income and want to grow my own medicine. I live in the San Joaquin Valley of California and it is really hot here in the summer. I can only afford to run a swamp cooler so my best daytime indoor temp is 82°F with 60% RH. I have a small tent 3x3x5 running a top fed deep water culture (5 gallon bucket), 6” hyperFan exhaust with plenty of CFM. I was running my day/night upside down to help with the heat. I have two small cheap Chinese LED fixtures. I started with 8 CFLs but the heat buildup was just too high. Remember my incoming air is already hot. I had to have something fast so that is why the Roleadro LEDs. Fortunately, I had most everything I needed to add CO2 and I programmed an Arduino Uno to inject the CO2 based on cubic foot calculations without letting the tent go over 95°F before turning the exhaust fan back on. I am actually surprised by the results so far. I made a NOOBZ mistake with my genetics as I chose Moby Dick CBD based on the high CBD, expected yield and flavor profile – all good for what I was looking for. I failed to notice that this strain needs a LOT of room to grow. The first clue should have been in the name – MOBY DICK!!!. Here is a picture of Mobina I thought she should have a girl’s name. I think I still have 4 or more weeks to go.


I want to upgrade my lights for my next grow. I have a fixed income. I will not be selling any pot to supplement my medical grow because I will not risk a stint at the cross bar hotel. So please don’t talk about the macro economics of spending more money to save more over the long term. I understand that already. Can a good COB based LED grow light be built for under $200.00? I can scrap together a frame. I want to mount the driver/s outside of the tent. Since vertical space inside the tent is at a premium I don’t think I need lenses or refractors but you tell me.
An idea would be check and see if you can get some 3070's. From what I've seen they grow the best bud.
 

Walterwhiter

Well-Known Member
Seeing how the drivers usually are between $60-90 that would be a stretch. Short answer yes you "can" but I wouldn't use this light for anything other than Veg. The point of using these lights is efficiency... not being cheap in the short term. Long term these light more than pay for themselves.


CXB3590DD36V5000K 2 COBS @3.6A ON 5.88 PROFILE HEATSINK
9 SQ.FT. CANOPY 92% EFFICIENT DRIVER @15 CENTS PER KWH
Total power watts at the wall: 298.91
Cobs power watts: 275
Total voltage forward: 76
Total lumens: 38701
Total PAR watts assuming 10% loss: 108
Total PPF: 482.76
PPFD based on canopy area: 577.38
PAR watts per sq.ft.: 12.0
Cob efficiency: 43.44%
Power watts per sq.ft.: 30.56
Voltage forward per cob: 38.22
Lumens per watt: 140.73
Heatsink riser thickness / number of fins / fin's length: 0.27in/14/1.0in
Heatsink area per inch: 260.01 cm^2
Total heat watts: 156
umol/s/W / CRI: 4.47 / 70CRI
Heatsink length passive cooling @120cm^2/heatwatt: 72 inches
Heatsink length active cooling @40cm^2/heatwatt: 24 inches
COB cost dollar per PAR watt: $0.86
Electric cost @12/12 in 30 days: $16.64
Electric cost @18/6 in 30 days: $24.71
Cost per cob: $46.5
Heatsink cost per inch cut: $1.74
Total cobs cost: $93
Total heatsink passive cooling cost: $125
Total heatsink active cooling cost: $41



CXB3590CD36V3500K 2 COBS @3.6A ON 5.88 PROFILE HEATSINK
9 SQ.FT. CANOPY 92% EFFICIENT DRIVER @15 CENTS PER KWH
Total power watts at the wall: 298.91
Cobs power watts: 275
Total voltage forward: 76
Total lumens: 33363
Total PAR watts assuming 10% loss: 93
Total PPF: 432.45
PPFD based on canopy area: 517.21
PAR watts per sq.ft.: 10.33
Cob efficiency: 37.44%
Power watts per sq.ft.: 30.56
Voltage forward per cob: 38.22
Lumens per watt: 121.32
Heatsink riser thickness / number of fins / fin's length: 0.27in/14/1.0in
Heatsink area per inch: 260.01 cm^2
Total heat watts: 172
umol/s/W / CRI: 4.65 / Estimated
Heatsink length passive cooling @120cm^2/heatwatt: 79 inches
Heatsink length active cooling @40cm^2/heatwatt: 26 inches
COB cost dollar per PAR watt: $1.02
Electric cost @12/12 in 30 days: $16.64
Electric cost @18/6 in 30 days: $24.71
Cost per cob: $47.62
Heatsink cost per inch cut: $1.74
Total cobs cost: $95
Total heatsink passive cooling cost: $137
Total heatsink active cooling cost: $45
Pretty good been doing some window shopping online playing with budgets for next year. What would be looking at for an 8×8 area?
 

PhotonFUD

Well-Known Member
He could salvage drivers from the chinese lamps and re-use them. Depends on how deep down the DIY rabbit hole he is comfortable with. If they have common 50w 40-70v cc drivers, he could probably run 2 36v cobs in series off each driver. With 2 drivers, that's 4 cobs.
 

Airwalker16

Well-Known Member
Maybe. Vero should be dumping the old vero 29's maybe catch a sale. The cheapest way I have seen is using a CPU cooler. 4 would run around $45. 4 cobs of your choice $15 to $45 a piece. Difference being efficiency. Run 4 at 400 watts give or take. Dimmer is nice. Drivers $50 give or take. Probably $250 total. Some people sell nice kits here. I use 16 3590's in ~15 sq feet. Two bars of 8. No lens or reflector.
I figure you buy 12 citi cobs $11/ec a 409watt Pairui driver $40, & 2 33" bar sinks $120. 6 on each one staggered. Also throw some fans on em too, $20. You'll have to spend a but more. Like $275. But you could sell your China leds possibly on e bay? That'd be a kick ass light.
 

Airwalker16

Well-Known Member
He could salvage drivers from the chinese lamps and re-use them. Depends on how deep down the DIY rabbit hole he is comfortable with. If they have common 50w 40-70v cc drivers, he could probably run 2 36v cobs in series off each driver. With 2 drivers, that's 4 cobs.
I was thinking that too, but no doubt they're running 300-800mA tops. He's gonna Wana run em at 1050;@ least. But hey, honestly, if you could run 12 Citis at 700mA, spaced on 3 bars of 4, you might be in a good spot with that much spread. Even with the low wattage.
@Growmau5 I'm pretty sure flowered a good 10'x5' area with like 8 bars of 4 crees at 700ma and did great. But I think he did better at 1050 or maybe it was 1400. I'm not sure. But he still did well.
 

PhotonFUD

Well-Known Member
I figure you buy 12 citi cobs $11/ec a 409watt Pairui driver $40, & 2 33" bar sinks $120. 6 on each one staggered. Also throw some fans on em too, $20. You'll have to spend a but more. Like $275. But you could sell your China leds possibly on e bay? That'd be a kick ass light.

Agreed on the 1212s for sure. Cobkits deal is still by far the most cost effective light source so far. Driver looks like a good choice but it is still $40 that could be saved re-using the chinese drivers if possible. I am of the under driving opinion, so 350 or 700ma is what I would recommend. That will also let you use a cheaper heatsink and mounting solution. Instead of going with those specific bars, he could hit a hardware store of metal supplier to get lengths needed for a fraction of the 120, something in the range of 20 to 40.

With the re-use of drivers and cheaper heatsink, he could probably get more cobs for the $200 budget; 18 running at 350ma would be nice, bright and cool. Might be a better option than going through the hassle of selling on ebay. Plus he can upgrade later as needed.
 

randydj

Well-Known Member
He could salvage drivers from the chinese lamps and re-use them. Depends on how deep down the DIY rabbit hole he is comfortable with. If they have common 50w 40-70v cc drivers, he could probably run 2 36v cobs in series off each driver. With 2 drivers, that's 4 cobs.
Not that deep they are working to some extent now don't want to FUBAR that.
 

CobKits

Well-Known Member
if youre really on a budget,

15 2700K A19 bulbs, 15W ea = $75
5 5000K A19 bulbs, 15W ea = $25
20 outlet-to-socket adapters = $20
5 4 slot power strips = $20

300W bloom rig for $140
turn off half the 2700Ks for veg (or buy a few more 5000K)

not cobs but SMDs driven under a watt each and a 6 year old could put it together
 
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CobKits

Well-Known Member
naw if you remote the driver you can hang those two fixtures from above easily. ive got a clever clip system but its in beta ;)
 
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