Parallel Wiring, Current Mirrors, Resistors, and Fuses

Hello All,

This is my first post here and I have an interesting question for you all:

I have seen a lot of static on the web about parallel wiring and current mirrors and resistors, but not much useful information. I know there are many different opinions about parallel wiring in our applications, but I know it can be done safely, and I want to use this method for a number of reasons. I plan on running 9 CLU028-1204's in parallel on an HLG-240H-42 at about 600ma. Since these CLU's are rated at 1150ma max., can't I just run a single 1A fuse inline at each COB to protect it in case of a thermal runaway situation? I am not too worried about it at this low current, divided between so many lights, but I want the protection to be in place anyway. I know this won't do anything to prevent a thermal runaway from occurring, but 1A fuses are a hell of a lot cheaper and easier to replace if something does go wrong. Thoughts?

its because its not necessary with proper design.

change your design from 1204 to 1208 and change your driver to an HLG-240H-36B and it will be impossible for any cob to go over 750 mA as the driver has a hard limit of 36V

1208s are a lot more efficient as well (20%)

or if youre married to the 1204s get an hlg-240h-42A driver which can be adjusted to limit voltage to 39V

I was hoping you would reply.

Cost is a factor here, the 1204's are cheeaapp. Do you have any good sources for the 1208? I want to run the B for the external dimming, though it would be nice to be able to limit the voltage.

CobKits said:

its because its not necessary with proper design.

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Is there any reason specifically not to do it as I described?

xX_BHMC_Xx said:

Is there any reason specifically not to do it as I described?

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Im not going to argue with anyone to each their own , read this and educate yourself :

http://www.ledsupply.com/blog/#article/931

Drift is inherent in diode construction. When current isnt regulated in a parallel config, there is a chance. Simply a chance, not a guarantee.

Abiqua said:

Im not going to argue with anyone to each their own , read this and educate yourself :

http://www.ledsupply.com/blog/#article/931

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Who's arguing? I'm not really sure what I should be getting from that link, care to elaborate?

Also, it seems the 1204 is rated at 920ma max. I was wrong.

For anyone that does not already know...
https://en.wikipedia.org/wiki/Current_mirror
Current Mirror: is a circuit designed to copy a current through one active device by controlling the current in another active device of a circuit, keeping the output current constant regardless of loading.

Thermal Runaway: Is a situation where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result.

xX_BHMC_Xx said:

Who's arguing? I'm not really sure what I should be getting from that link, care to elaborate?

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i looked at the link,there are a few more links within the link with more info.alot of these cob manufacturers actually tell us they prefer series wiring for their products.the best protection for parallel wiring would be to use enough heatsinking to absorb the extra heat after you lose a cob and the rest are now getting additional power.so you would not want to use a 60w passive heatsink on a 50w cob setup in parallel,you would need more like 120w or better.or use active cooling and use fusing or current mirrors.or just wire in series lol.

If your set on a 250 watt driver and paying 10 bucks a cob you can go with a HLG 240H- C700 and 10 or 11 vero18 SE D versions run in series they are 10 bucks and change a peice. The new SE's have push in connectors so no need for holders. It is right on the edge but you could possibly run 12 of those on that driver. Instead of buying fuses and resistors just buy a extra cob or two with that cash and run those jokers in series.