How to Combat Thermal Runaway

Grower899

Well-Known Member
So ive built 2 lights, each consists of 7 f series 2ft strips. Each set of 7 is wired in parallel to a meanwell 185 24a. In each light the strip closest to the driver gets very warm, the second gets pretty warm, not quite as warm as the first. The remaining 5 strips remain cool to the touch after 12 hours. Anything i can do about this, other than buying cc drivers and wiring in series? Im 90% sure im experiencing thermal runaway, and the web mentions current limiting resistors but im still researching this bit. Might end up switching drivers and rewiring.
 

Grower899

Well-Known Member
Maybe, maybe not. Tell us in detail about your wiring....
The positive of each strip is connected, as well as the negatives. A short run of wire from each connector to the next. I tried to make them as close as possible in length. Stranded copper wire 18ga. Ordered solid but they sent stranded. Anything im missing?
 

1212ham

Well-Known Member
We need a better description, diagram or picture. I'm 90% sure it's voltage drop rather than thermal runaway. ;)
Does the driver connect to strip #1, with #1 connected to #2 and #2 connected to #3 and so on?
 
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Grower899

Well-Known Member
We need a better description, diagram or picture. I'm 90% sure it's voltage drop rather than thermal runaway. ;)
Does the driver connect to strip #1, with #1 connected to #2 and #2 connected to #3 and so on?
Yes, exactly right strip 1 is connected to the driver and each subsequent strip is connected to the previous strip.
 

Grower899

Well-Known Member
Instead of going from one strip to the next like that, get some terminal strips like this:
View attachment 4075973

Run 14G to the distribution terminal, then 18 to each individual strip.
I like that and wish i woulda grabbed some. Ive seen them but totally forgot about them. Gonna grab a couple pair locally today if i can if not ill grab some online. And go 14ga from terminal to driver then 18fa from terminal to each strip yeah?
 
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Schalalala

Active Member
Probably the easiest fix is to mount the driver somewhere else in order to get all strips to the same temperature. Besides that, placing a fan on the problematic spot could also work. Last but not least, you could use current resistors. There are loads of good infos about this topic, google will help you to find the proper resistor.
 

1212ham

Well-Known Member
I like that and wish i woulda grabbed some. Ive seen them but totally forgot about them. Gonna grab a couple pair locally today if i can if not ill grab some online. And go 14ga from terminal to driver then 18fa from terminal to each strip yeah?
Excellent, that will fix your problem. With 7 strips end to end the voltage has dropped by the end of the line. If you can't find a terminal strip, a couple wire nuts will work just fine. If you want it going asap, just twist the wires together and tape.

Wago's are popular, but the largest is for only five wires. You would use 1 connecting to 2 more to have enough ports for 7 strips, so you'd need 3 for negative and 3 for positive.
 
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Grower899

Well-Known Member
Excellent, that will fix your problem. With 7 strips end to end the voltage has dropped by the end of the line. If you can't find a terminal strip, a couple wire nuts will work just fine. If you want it going asap, just twist the wires together and tape.

Wago's are popular, but the largest is for only five wires. You would use 1 connecting to 2 more to have enough ports for 7 strips, so you'd need 3 for negative and 3 for positive.
Awesome thats good to hear. I may end up just going the wire nut route as i have plenty of those. Thanks for the info!
 

Grower899

Well-Known Member
Excellent, that will fix your problem. With 7 strips end to end the voltage has dropped by the end of the line. If you can't find a terminal strip, a couple wire nuts will work just fine. If you want it going asap, just twist the wires together and tape.

Wago's are popular, but the largest is for only five wires. You would use 1 connecting to 2 more to have enough ports for 7 strips, so you'd need 3 for negative and 3 for positive.
Actually 1 more question. 7 strips have 14 pos and 14 neg terminals. 2 per strip. Is it necessary to use both sets on each strip, or 1 positive and 1 negative wire from each strip will work?
 

CobKits

Well-Known Member

boyd crowder

Active Member
@nfhiggs i been looking to find these strips but the best i can locate are like 30$ for a pair for 8ups
i can get 2 boxes of wagos for that. my wagos work fine , i just want a cleaner setup - @CobKits I dont see how those terminal strips on the ideal pages are interconnected - is that something ill manually have to do to use them?
 

nfhiggs

Well-Known Member
@nfhiggs i been looking to find these strips but the best i can locate are like 30$ for a pair for 8ups
i can get 2 boxes of wagos for that. my wagos work fine , i just want a cleaner setup - @CobKits I dont see how those terminal strips on the ideal pages are interconnected - is that something ill manually have to do to use them?
I found them at Fry's Electronics. I think they were 6-7 buck apiece. You have to add the little shunts between each contact pair to configure them as a bus. You could also use power distribution blocks that are commonly used in car audio systems.

This is like the ones I have

Here is a five pack with jumper strips included for $12
 

CobKits

Well-Known Member
@nfhiggs i been looking to find these strips but the best i can locate are like 30$ for a pair for 8ups
i can get 2 boxes of wagos for that. my wagos work fine , i just want a cleaner setup - @CobKits I dont see how those terminal strips on the ideal pages are interconnected - is that something ill manually have to do to use them?
theyre like wirenuts/wagos, all the ports are interconnected
 

boyd crowder

Active Member
lol @CobKits ty - i kinow what they are just havingtrouble locating the inexpensive ones cause i dont know the trade name of them
we called em rails/power rails but all ive found is terminal blocks
thanks for that links @nfhiggs
 
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