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Topic: Life expectancy of LED modules / Sticks (Read 1 time) previous topic - next topic

pgmartin

#5
Feb 26, 2013, 04:10 pm Last Edit: Feb 26, 2013, 04:25 pm by pgmartin Reason: 1
Pardon my awful description that led to misunderstandings.

The led modules look like a brick of plastic, where the leds and resistors are placed, and all is covered with more melted plastic. You can see inside the plastic some conventional THT resistors. All this info was in the effort to describe the product. Here is a better picture of some similar modules that have only 3 leds:

The modules look ok from the outside, though the leds are no longer bright enough and some of them do no longer work.

12V come directly from a commercial switching power source with 2.5 amps capacity (Can this be blamed?). Each led module consumes 40mA, and I have 42 modules.

Thanks for your help guys. looks like I shoudn't have trusted the dealer who said that these where 12V modules, and lower it a little bit. I'll try dimming with PWM on the high side.

fungus


12V come directly from a commercial switching power source with 2.5 amps capacity (Can this be blamed?).


Measure the voltage under load...?


Each led module consumes 40mA, and I have 42 modules.


Five LEDs could be arranged as a string of 2 and a string of 3 in parallel to work from 12V. 20mA for each string adds up to 40mA. That's just a guess though.

Do the dead LEDs form any kind of pattern in the modules? Do they die in similar groups of two or three LEDs?
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

Zapro

Those LED's are not genuine Pirahna. I'm pretty sure those "Pirahna" LED's are very cheap, and that's what you should expect from a no-name product form china. The LED dies inside are under-rated and will not last very long. Nothing to do about that.

// Per.

pgmartin

Thanks fungus. In most of the cases a pair of leds dies, and the other 3 survive.
Zapro: I wasn't even aware piranha was a brand  :smiley-mr-green:
You are right, I was a victim of "EL CHEAPO" Leds Made in China.
Problem is....everything I can buy arround here are from the same origin.

fungus


Thanks fungus. In most of the cases a pair of leds dies, and the other 3 survive.


I think we're getting closer to the truth.

Can you see the resistor color codes through the plastic? Are they the same value or different?


You are right, I was a victim of "EL CHEAPO" Leds Made in China.
Problem is....everything I can buy arround here are from the same origin.


Does your power supply have a voltage adjustment screw? Try turning it down a bit :)
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

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