SOS DIY COB NOOB needs help.

Hey guys so here is my issue, my light will not light up.. lol

The details of my light are as follows


Driver = Meanweal 185H-48A X1
COBs = Citi 48-1212 X 4
Ideal holders X 4
ideal reflector adapters 50-21--AN X 4
Angelina reflectors X 4
Heatsinks cheapos X 4 (But mounted on a Hugh piece of aluminium)

On the AC side of the Drive i connected the wires Green to Ground, Blue to white, and Brown to Black.. I checked the outside / DC side and i was getting 49 volts. From the outside or DC side i wired the red from the drive to the + of the 1st COB, then from the - side i went to the 2 cobs + side and continued till the last COBs - side which ran back to the red wire of the Driver.. Plugged it in and nothing..

I ripped it apart twice thinking i did something wrong but i cant figure this out.. How can test the COBs? Could the holders possibly be the issue by not making a good connection? Could the Cobs be bad? Any input would be great,






Cheers,

Looks like the output voltage of the driver is 48v. The cob needs somewhere near 32v. (DO NOT Try the series with just one cob. Just looked at specs and single cob can't handle that current). Looks like the driver cannot handle more than 1 cob (in a series). Just looked quick but probably your issue.

youre wiring cobs in series which would require ~ 4x36V = 144V to run

it will never ever run on a 48V driver

you need to wire the cobs in parallel, in which case the driver will deliver adequate voltage to the cobs

The photos were taken after hrs of pulling my hair out and trying to trouble shoot. The photo with the Drive is actually a 2nd one that i wanted to test to make sure the original driver was not the issue..

As far as only running 1 Cob, here are the stats for the driver.

F#CK!!! Thanks Ckits.. I need u on speed dial!

Ya don't wire just one unless that amperage is covered by the cob (Seems these cobs have a max of 2760 mA). Those directions must be for parallel wiring. Personally I would get a new driver and wire them in a series. You could do parallel but I would suggest resistors inline on each cob if you do. I think if you run them in parallel with four cobs you will only be driving at a little over 900 mA. Do you concur cobkits?

i wouldnt sweat it. make sure connections are solid. if you have 4 on there and drop 1 cob youll go from 1050 to 1400 mA, if you drop 2 you'll go to 2800 mA. but yeah dont hook one up unless the current knob is turned way down on the driver

ive tested those out past 3600 mA for short periods

- Series is safer than parallel. Stick with the statistically safer method. I don't know which driver you need, but as CobKits said, you have to start with that Primary Output Voltage of nearly 150V.

- It's inadvisable to use the same color of wire throughout the project. Take a look at how Timber Grow Kits color-codes their wires and Chip-Loks. Buy several different colors of wire and do the same thing with your stuff. I'm here to tell you that it's way too easy to grab the wrong wire and blow the whole thing up. Maybe even hurt yourself.

- I'm surprised nobody else said anything about the heatsinks. I'm sorry, but those tiny sinks won't cut it. Blowing air across them would help, but not enough. You mentioned that they're strapped to a big bar of aluminum. That aluminum bar isn't going to help at all. For one, it's a bar. You need fins and contact with air, not an ingot. If the small heatsinks had flat bases, creating a large contact patch with the bar, you might transfer some small amount of heat to the bar. But they don't. They only contact the bar in two patches, under each foot.

Don't kid yourself. The sinks are way too small and the bar will serve no purpose. You have to address this problem before you get the right size driver and light 'em up.

Damn it.. i was told the sinks could handle up to 50w Cobs.. At this point i just want them to turn on.. If and when they do light up, i will closely monitor the heat, and go from there.. As far as the bar, could i just drill a bunch of hole through it and add a couple fans? At 38watts each i really thought i would be fine.

i really appreciate the input Mellodrama, ill post more tomorrow when progress has been made.

those sinks are def on the lighter side. 38W is pushing it. 20-25 maybe

I started out with a half dozen CXA3070's a few years ago. I had computer parts laying around, so I bolted them to CPU heatsinks. I ran my CXA3070's at 700mA. The 3070's produce about 27W at 700 mA. All of the CPU heatsinks I used were at least 3X as robust as yours. And the fins were the traditional configuration, designed to pull heat evenly from the base. I don't know what rationale drove the design of your heatsinks, but their shape seems all wrong to me.

My CPU heatsinks got uncomfortably hot near the COB without active cooling so I added fans. I ran mine more conservatively than you propose to run yours, I used heatsinks that were at least 300% larger, and I ran fans. And I swore I'd never use smaller heatsinks because of the chance that a fan would fail and the poor COB might kill itself.

I'm sorry to be the bearer of bad news, but the aluminum bar just isn't going to make a difference. There's not enough thermal conductivity between the COB and the bar. Sell the bar to help buy some bigger heatsinks.

I understand your excitement to make light. But the best thing you can do right now is set the lights aside somewhere safe, get more colors of wire, buy the right driver, maybe buy some of those big SST140 Cooliance heatsinks, get some good thermal paste, and start over. Is it gonna cost more than you thought? Yeah, probably at least twice as much.

Creating a parallel wiring circuit is not too difficult.

Those heatsinks look like they are designed for Solid State Relays !
I'd definitely get better heatsinks with all that $$ equipment.
Props for giving DIY a go though, all the help/advice you need is above!

Parallel isn't difficult. That's not the issue. Parallel wiring exposes you to a potentially catastrophic situation called thermal runaway. Apparently you can put more stuff into your circuit to guard against runaway, but why bother when series wiring guarantees that thermal runaway won't be an issue? Yes, series wiring means higher voltage at the driver, which could be considered dangerous. Higher voltage means that you need to take appropriate precautions, such as air gap, good insulation, bombproof connections, thorough labeling of wires, etc. The things you should be doing anyway when messing with electricity.

If a grower is fully aware of the trade-offs and decides to go with parallel, I'm not gonna criticize. I think series makes more sense for the rest of us.

Mellodrama said:

Higher voltage means that you need to take appropriate precautions, such as air gap, good insulation, bombproof connections, thorough labeling of wires, etc. The things you should be doing anyway when messing with electricity.

Click to expand...

Parallel wiring means that you need to take appropriate precautions, such as proper driver selection, number of cobs, bombproof connections, thorough labeling of wires, voltage adjustment and current limitng as necessary etc. The things you should be doing anyway when messing with electricity.

Hey guys, thank you all for the input much appreciated. So here is where i now stand. The light is up and running and i am happy!! Once i got her fired up, she was running too hot or at least i think so.. The sink got up to 145 i could still touch it but couldn't hold my finger there very long so i simply turned the juice down to around 110watts or so and temps are stable at 124 degrees.. is this temp ok for the COBs to be at?





This little DIY light was fun to build and a great learning experience. The bar holding the COBs was free, the sinks were 4.95 per on amazon, so when im ready to push the COB and driver to their max and change out the design and sinks, i really will haven't lost much but time.. Thanks again,

Cheers,

measure the voltage across teh cob at first startup and after temperature stabilizes and you can estimate Tc

Something is definitely fucky.

CobKits said:

measure the voltage across teh cob at first startup and after temperature stabilizes and you can estimate Tc

Click to expand...

Each individual cob or the entire light?

if you want a good average measure across all 4 cobs, 140V or so

dont be surprised if it continues to drop and drop and drop slowly thats a sign of poor heat dissipation