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5050 led strip lights - loss of intensity

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Wp100

Well-Known Member
Hi,

Have been using some small lengths , 30cm, of the waterproof silicone covered 5050 blue leds strip lights in a well protected aquarium hood.

They are secured by their self adhesive to an alum backplate to help dissipate the heat and used along side some compact tubes.

Their light output is initially good but after a month or two the output reduces to about 30% but the voltage and current remain constant at 11.19v and 130ma.
Even removed from the alum backplate they remain dim and at the same current, so dispelling the idea of any shorting on the backplate.

Have tried 2 different makes of these 5050 blue leds both with similar loss of intensity over a couple of months

Bit puzzled as to why ? could the heat from the nearby compact tubes be affecting them so dramatically; though no signs of any burning ?

They are run by a 1000hz pwm /power darlington to give a slow start up and shut down and on approx 12 hours a day.

Any thoughts welcome....
 

audioguru

Well-Known Member
Most Helpful Member
I looked in Google and found many brands. Some were cheap no-name-brand Chinese ones sold on e-bay and others were high quality and sold for pools and aquariums.
Some are very bright and use a higher current than the dim ones. Many operate on 24V.

Please post the datasheet for your strip lights. We need to know how many LEDs use 130mA and if there are current-limiting resistors in the strip.

What is a compact tube? Incandescent or fluorescent? How many Watts fore each?
 

Wp100

Well-Known Member
Hi,

They are Ebay cheapies, though would not have thought they would die out that fast.

The strip is 24cnm long and has 14 5050 arrays, each array has its own resistor - no datasheets available other than basic light spectrum of 'blue' !

The well ventilated hood has 2 x 18w compact fluoescent tubes.

Assume its something to do with the heat, will have to try a strip in free air and see if it dies as quick, though strange that the current remains almost the same ?
 

audioguru

Well-Known Member
Most Helpful Member
Hee, hee. Cheap means POOR QUALITY and short life.
They make cheap dim LEDs then blast too much current to make them appear bright for a short time.

I have a name-brand clock radio that has been showing the time continuously for about 39 years and I can't see its display anymore in the daytime.
The current doesn't change. The brightness changes. High current makes the brightness dim sooner.
 
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