D.I.Y. 200W CITIZEN COB LED BUILD
- Thread starter Hydro
- Start date
Greenthumbskunk
PICK YOUR OWN
Ya I understand the appeal of wanting to wire in parallel when you can have a light start running away and burn up easier than series.
Greenthumbskunk
PICK YOUR OWN
Should be don't understand the appeal.
TerpyTyrone
LED Recruiter
ChiefRunningPhist
Drunk on Knowledge
Thanks for the welcome @TerpyTyrone !
Thermal runaway only happens in CV driver solutions. It does not matter if it's wired in series or parallel.
2 things to take note of.
1 - when LEDs heat up, their forward voltage drops.
2 - when using a CV or constant voltage driver the driver tries to maintain a constant voltage.
When your chips heat up and require less voltage to flow the same current, the driver continues to maintain the CV you set and so the driver will flow more current to the chips than what they normally would get if they weren't hot.
This phenomenon can compound to failure. The chip gets hot and flows more current, so it gets hotter, so it flows more current, so on and so forth, till POP! No more chip.
The boards are wired in series and parallel combinations, so there's no way of getting around parallel or series wiring. What's important in terms of thermal runaway is the driver type.
When chips heat up with CC drivers, or CV drivers with current limiting engaged, then nothing happens except the driver doesn't need to supply as high a voltage to flow the same current. So when using CC or current limited CV, as the chips heat up the overall wall wattage goes down. If you have lights that heat up you can notice this phenomenon by checking wall watts when you fire up the light when it's at a cool temp vs when it's been running and hot.
After all that I'm going to say that CV drivers when used in conjunction with their Io POT are just as safe as CC drivers. In fact if operating via current limiting, they will operate the same way, both will operate as CC drivers but the true CC drivers will have more Voltage to use, and the true CV drivers will have more Amps to use. If current limiting is not applied in CV drivers, then they operate in a different way, they operate as true CV or constant voltage drivers.
CC can't operate as CV, but CV can operate as low voltage range CC.
Thermal runaway only happens in CV driver solutions. It does not matter if it's wired in series or parallel.
2 things to take note of.
1 - when LEDs heat up, their forward voltage drops.
2 - when using a CV or constant voltage driver the driver tries to maintain a constant voltage.
When your chips heat up and require less voltage to flow the same current, the driver continues to maintain the CV you set and so the driver will flow more current to the chips than what they normally would get if they weren't hot.
This phenomenon can compound to failure. The chip gets hot and flows more current, so it gets hotter, so it flows more current, so on and so forth, till POP! No more chip.
The boards are wired in series and parallel combinations, so there's no way of getting around parallel or series wiring. What's important in terms of thermal runaway is the driver type.
When chips heat up with CC drivers, or CV drivers with current limiting engaged, then nothing happens except the driver doesn't need to supply as high a voltage to flow the same current. So when using CC or current limited CV, as the chips heat up the overall wall wattage goes down. If you have lights that heat up you can notice this phenomenon by checking wall watts when you fire up the light when it's at a cool temp vs when it's been running and hot.
After all that I'm going to say that CV drivers when used in conjunction with their Io POT are just as safe as CC drivers. In fact if operating via current limiting, they will operate the same way, both will operate as CC drivers but the true CC drivers will have more Voltage to use, and the true CV drivers will have more Amps to use. If current limiting is not applied in CV drivers, then they operate in a different way, they operate as true CV or constant voltage drivers.
CC can't operate as CV, but CV can operate as low voltage range CC.
Last edited:
ChiefRunningPhist
Drunk on Knowledge
Thanks friend
TerpyTyrone
LED Recruiter
Ya see that @Heisenbeans I should have my name changed to recruiter or rep!!Thanks for the welcome @TerpyTyrone !
Thermal runaway only happens in CV driver solutions. It does not matter if it's wired in series or parallel.
2 things to take note of.
1 - when LEDs heat up, their forward voltage drops.
2 - when using a CV or constant voltage driver the driver tries to maintain a constant voltage.
When your chips heat up and require less voltage to flow the same current, the driver continues to maintain the CV you set and so the driver will flow more current to the chips than what they normally would get if they weren't hot.
This phenomenon can compound to failure. The chip gets hot and flows more current, so it gets hotter, so it flows more current, so on and so forth, till POP! No more chip.
The boards are wired in series and parallel combinations, so there's no way of getting around parallel or series wiring. What's important in terms of thermal runaway is the driver type.
When chips heat up with CC drivers, or CV drivers with current limiting engaged, then nothing happens except the driver doesn't need to supply as high a voltage to flow the same current. So when using CC or current limited CV, as the chips heat up the overall wall wattage goes down. If you have lights that heat up you can notice this phenomenon by checking wall watts when you fire up the light when it's at a cool temp vs when it's been running and hot.
After all that I'm going to say that CV drivers when used in conjunction with their Io POT are just as safe as CC drivers. In fact if operating via current limiting, they will operate the same way, both will operate as CC drivers but the true CC drivers will have more Voltage to use, and the true CV drivers will have more Amps to use. If current limiting is not applied in CV drivers, then they operate in a different way, they operate as true CV or constant voltage drivers.
CC can't operate as CV, but CV can operate as low voltage range CC.
I'm here to better this forum with seasoned growers!
TerpyTyrone
LED Recruiter
@The Governor?
Lead Recruiter?
Lead Recruiter?
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TerpyTyrone
LED Recruiter
Well cant all be master builders! Or baters
pleasecheese
Really Active Member
Which heat sinks do you orefer. I noticed you switched to the round pin style for the diy vs the one in this pic. Thank you very much for making this thread. So much valuable information.
TerpyTyrone
LED Recruiter
Hydro
PICK YOUR OWN
I used the 120mm heatsinks that were predrilled and tapped for BJB holders (CLU048/CREE CXB series etc). TBH, I cant remember where I got them? I do know you can get 140mm set up the same way for about $19 ea. at rapidled, cobkits, and you will likely be able to find better deals than that overseas at alibaba etc.
pleasecheese
Really Active Member
i was debating between the round pin style but they are a little pricey. They have a 4.6" serrated heatsink that can be custom cut at heatsink usa. in the reviews someone noted that a 4" square would dissipate 45w of heat. they are 10bucks each. Im wondering how they compare to the round pin style as far as heat goes.
Hydro
PICK YOUR OWN
The 120mm pinfin are rated for like 65W I believe. When it comes to HS, your better to be anything over than slightly under. The stuff I used for my first build was from heatsinkusa. It was the 5.886
5.886" - HeatsinkUSA
www.heatsinkusa.com
pleasecheese
Really Active Member
Thanks. I appreciate your time. That's the one @NoWaistedSpace recommended as well. I was looking at the different schematics for each heatsink and getting different ideas.The 120mm pinfin are rated for like 65W I believe. When it comes to HS, your better to be anything over than slightly under. The stuff I used for my first build was from heatsinkusa. It was the 5.886
5.886" - HeatsinkUSA