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Fried 3 leds - 5 x 3 watt LEDs and mean well lpc 35watt 700ma constant current driver Answered

Hi,

I have 5 leds all of 3 watt each, i used the Mean Well LPC-35-700 constant current driver

I hooked up all the leds to the driver in series, but as soon as i turned it on it fried 3 leds 1x 660nm, 1 x 450, and one 630nm led, but the last 2 leds are stil working.

Could anybody let me know what did wrong, if you need more specs i can  give you

9 Replies

user
steveastroukBest Answer (author)2013-03-24

What current were the LEDs supposed to run on ?

Steve

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MistaMasta (author)steveastrouk2013-03-24

All specs/ leds where at 700ma,
Red 630nm Vf 2.3v
Red 660nm Vf 2v (some say 350ma, most say 700ma)
Blue 450 nm Vf 3.3v

Driver specs
http://www.rapidled.com/mean-well-lpc-35-700-constant-current-driver/

For driving 1 string of 3-14 CREE XP-/XT- LEDs in series. Can also be used for XP-G and our red LEDs.

700mA Constant current
9-48V
120-240V AC input
Epoxy encapsulated case
Short circuit / Over voltage / Over current protection
100% full burn-in test
50,000 hour MTBF

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MistaMasta (author)MistaMasta2013-03-24

And is it always true that with a constant current driver i dont need to add resistors inbetween, i tried to add 68 ohm resistor when i was testing only 3 leds, it worked but only the resistors fried, so that i wont try again

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steveastrouk (author)MistaMasta2013-03-24

Yes, assuming the LEDs will handle 700mA, it sounds like some wouldn't

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user
MistaMasta (author)steveastrouk2013-03-24

Could it be that maybe the seller on ebay sold me lower wattage leds that mayb run on 350ma, cause he did not really have all the specs on his site but he told me all are 3 watt.

For example if i would make 2 string of 3 x 700ma leds would that mean that 1 string will use 350ma and both strings use 700ma?

Thnx for yr fast replies

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steveastrouk (author)MistaMasta2013-03-24

Absolutely. I'd not be at ALL surprised if that was true, I'm sorry to say.

Steve

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MistaMasta (author)steveastrouk2013-03-24

Thnx again, would you know a way to test leds if one does not have any specs and without blowing them up

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steveastrouk (author)MistaMasta2013-03-24

Tricky. The only criterion I can think of is temperature. I'd aim to ensure the heatsink temperature stays comfortable, and ramp the current up from 200 to 700mA.

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frollard (author)2013-03-24

*Steveastro answer is the long and short of it: low quality components means too many variables.

1) Is the cc 700mA accurate?
2) Are the leds ACTUALLY rated for 700,
and 3) were the heatsinks on the leds adequate?

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