If i have my lights setup on heat sink like in image above with thermal compound, do you think there will be any problems? There will also be two fans (push/pull) inside canopy. If they are running at the rates they are now supposedly.

We do not simply guess. Instead we look at the datasheets for the LEDs, the heatsink and the fans then we CALCULATE (using simple arithmatric) if there is enough cooling.

On a side note, i dont think my drivers have a SVR2 throttle to control current, anyway for me to know for sure? Is there any that i can install externally from the driver unit?

The datasheet for your driver will show a "throttle" if it can use one.

 

We do not simply guess. Instead we look at the datasheets for the LEDs, the heatsink and the fans then we CALCULATE (using simple arithmatric) if there is enough cooling.

The datasheet for your driver will show a "throttle" if it can use one.

I dont know if you have skimmed through the entire thread. Here is the datasheet for the LED http://www.ebay.com/itm/10-X-3W-White-HIGH-POWER-Star-170LM-6500K-140-3watt-LED-/120989910849?pt=US_Car_Lighting&hash=item1c2b8f8741

I am running 10 of the white LED in series on a single Mean Well LPC-35-700 constant current driver. The spec sheet to the drivers is here: http://www.meanwell.com/search/LPC-35/default.htm
What is to blame here, the driver giving about 850mA or the LEDs?

 

The CHEEP (cluck, cluck) Chinese LEDs do not have a detailed datasheet that spec's their required cooling so they will probably overheat then fail soon.

The CHEEP driver does not meet its current-limiting spec.

Why buy lousy CHEEP foreign junk instead of good name-brand stuff?

 

The CHEEP (cluck, cluck) Chinese LEDs do not have a detailed datasheet that spec's their required cooling so they will probably overheat then fail soon.

The CHEEP driver does not meet its current-limiting spec.

Why buy lousy CHEEP foreign junk instead of good name-brand stuff?

I thought Mean Well was a good brand of LED drivers? a couple forums seemed to say good about them.

I had the 20 white LED's running (10 on each driver) for over an hour now. They do not get "hot" to the touch and i can hold on to them without letting go. The heatsinks after an hour are only lukewarm. I think i should be in the norm. We'll see then i guess.

 

Mean Well (cluck,cluck) is Chinese. Your cheap LEDs are also Chinese.
Most Chinese parts do not work properly/do not last long.

Almost everything sold on E-Bay is from cluck cluck land.

 

Hello,

@ Audioguru,
If Mean Well is such a bad product, why would Farnell sell it?
http://uk.farnell.com/mean-well/lpc-20-350/psu-20w-single-output/dp/2114209

Mean Well comes from Taiwan.

Bertus

 

You don't actually need resistors for 12V electronic transformer + LED.
I have made experiments. If the current increases, voltage will drop just a little.
So there is no thermal runaway.

Also you can adjust voltage +/- 10%.

700mA or 850mA are no difference really. If it was 1.4 Amps then it is a difference.

If you want long-life LEDs, run them at 70% current or less.

What I believe however the current is not important. The temperature is important. If you have a good heatsink, you can run them at full current.

I used CFLs at too high temperature- first bulbs failing after 1/2 year...

Resistors only should be used for indication LEDs (2.2K to 4.7K).

 

The spec sheet for the Mean Well power supply says it has "Constant Current design with 5% accuracy". Then why does its output current slowly rise from 700mA to over 800mA?

The spec sheet says "The unit might not be suitable for lighting applications in EU countries".

Taiwan is governed by The Republic of China. It was called Formosa a long time ago then it was Japanese for about 50 years before China took it.

 

Meanwell is the TOP (#1) name in LED drivers.. They are NOT "Cheap" Chinese crap.. (but the LEDS are ) Meanwell is well know for their reliability.. but like any company sometimes stuff happens. Its possible you have a bad driver. (But I doubt it)
You can always send them back for a replacement if you are 100% sure you are getting an accurate current reading.

And seeing the image of the heatsinks you will have NO PROBLEMS running them at full current.. (remember thermal compound should be applied as thin as possible or its just hurting the temps)

 

I use 30W white LEDs mounted on Pentium II heatsinks. And the fans are total crap, need to drive them with higher voltage.

VGA coolers are even more effective.

The assembly is for 30W? Way overdone. You could use 200W with that or even more, if you use fans effectivly.

 

I use 30W white LEDs mounted on Pentium II heatsinks. And the fans are total crap, need to drive them with higher voltage.

VGA coolers are even more effective.

The assembly is for 30W? Way overdone. You could use 200W with that or even more, if you use fans effectivly.

yeah the heatsinks are overkill but so what...
IMO the wire is too small. I use 20AWG
Measure the voltage right at the driver output with it all hooked up. what do you get? maybe try removing 1 LED from the circuit and see if its more stable. You might just be running at the max and it can't regulate properly due to the Vf from the LEDs and added resistance from the small wire.

 

I use 30W white LEDs mounted on Pentium II heatsinks. And the fans are total crap, need to drive them with higher voltage.

VGA coolers are even more effective.

The assembly is for 30W? Way overdone. You could use 200W with that or even more, if you use fans effectivly.

This assembly is 20 wites (60 watts), 5 blues (15 watts) and 8 red (~25 watts).
Looks to be about 100 watts of power. But i only plan to use the whites mostly. Red and Blues will be on separate switch and will not be on as much as whites.

 

yeah the heatsinks are overkill but so what...
IMO the wire is too small. I use 20AWG
Measure the voltage right at the driver output with it all hooked up. what do you get? maybe try removing 1 LED from the circuit and see if its more stable. You might just be running at the max and it can't regulate properly due to the Vf from the LEDs and added resistance from the small wire.

I was measuring from the cathode side of LEDs. Will try the anode when i have a chance. and removing an LED. But the thing you say about the small wire causing resistance. That doesn't make sense according to ohms law. If resistance is higher, the current would be smaller, wouldn't it?

I only used smaller wire to avoide the risk of shorting out the setup because the bolts are close to the star leads and if too much solder gets in the way, the electricity will travel down the heat sinks. And the wires do not heat up either
But yes, i agree, the LED's are the only cheap thing i bought. i will see how long they last me.

 

If this was engine/mechanical thread, i would say that Made in China is the next best thing to Made in USA. Made in Taiwan is the worst for mechanical tools. but this is about electronics so it's a dark forest for me somewhat.

 

Replace the defective YingYang LED driver that does not limit the current to 700mA plus or minus 5%.

 

yeah the heatsinks are overkill but so what...
IMO the wire is too small. I use 20AWG
Measure the voltage right at the driver output with it all hooked up. what do you get? maybe try removing 1 LED from the circuit and see if its more stable. You might just be running at the max and it can't regulate properly due to the Vf from the LEDs and added resistance from the small wire.

MCGYVR, you were right from the start about the multimeter, except it wasnt a calibration issue, but a bad battery. I went out replaced it, and now everything is working below 735mA. Now a few things i should ask before i finish this off.

What is the max temp that these type of 3W LED's can withstand? I will be checking the temp with a IR Thermometer to look out for if the enclosed box with fans can stand the heat.

Also, would it be a good idea to just hook up a ground wire to the heat sinks as a fail safe or not needed?

I'm in process of installing everything inside canopy. Already got 6amp 125V rated power slide switches wired up to a power cord (thanks for that too!). All that's left if to connect the leads from drivers to the LEDs, close everything up, power it on, and keep an eye out for temps.

Thanks again!

 

Anything above 80C is bad even they will withstand more than 100C.

Some LEDs actually will dim or blink if they overheat. Others may burn out, fully or partially, sometimes they can recover by random.

If possible keep max. temperature at 60C.

The heatsink temp. is always 10C to 20C lower than the actual LED temperature. So it is adviseable to keep temperature to a level you can still comfortably touch the heatsink. If it gets warm or hot, this is not a problem, but if you spray water vapour, and it frizzles instantly with a hissing noise, temperature is too high!

Also VGA coolers are not really good for temperatures higher than 80C.
They will withstand 100C, but it is not clear for how long.

As I say, 60C is a reasonable margin.

You also must care for the enclosure or environment, the airflow may become blocked substantially, and the whole space may heat up.

So this may cause another rise of 10C to 20C.

I made an experience with blue LEDs, I supplied only 12V to the fan, while normally, I run them at much higher voltage. One LED burned out actually. I replaced it with a red LED actually on another sink!

The capabilities to withstand heat are different from LED to LED. Some can tolerate really high temperature.

 

Anything above 80C is bad even they will withstand more than 100C.

Some LEDs actually will dim or blink if they overheat. Others may burn out, fully or partially, sometimes they can recover by random.

If possible keep max. temperature at 60C.

The heatsink temp. is always 10C to 20C lower than the actual LED temperature. So it is adviseable to keep temperature to a level you can still comfortably touch the heatsink. If it gets warm or hot, this is not a problem, but if you spray water vapour, and it frizzles instantly with a hissing noise, temperature is too high!

Also VGA coolers are not really good for temperatures higher than 80C.
They will withstand 100C, but it is not clear for how long.

As I say, 60C is a reasonable margin.

You also must care for the enclosure or environment, the airflow may become blocked substantially, and the whole space may heat up.

So this may cause another rise of 10C to 20C.

I made an experience with blue LEDs, I supplied only 12V to the fan, while normally, I run them at much higher voltage. One LED burned out actually. I replaced it with a red LED actually on another sink!

The capabilities to withstand heat are different from LED to LED. Some can tolerate really high temperature.

Thanks for the quick reply. I will see what it will run at when i get everything wired up. If i have to, i may decide to improvise and drill bunch of small holes on the opposite side of fans and top for added ventilation. We'll see.

 

Ground wire on heat sink will not hurt anything right?

 

Ground wire on heat sink will not hurt anything right?

No need for a ground wire on the heatsink. Install one if you want though.

And make sure you set the emissivity on the IR gun based on the material/color you are trying to measure or it can be off quite a bit.
IR guns are only good for quick spot check measurements of known emissivity materials.

Glad you got it sorted out.. All this because you didn't check the battery.. Slap yourself...twice..no three times

Now where is Audioguru to "cluck cluck" and spell "cheap" wrong on these "horrible" drivers again..