12 x 5mm LED light fails ?

Thread Starter

RodneyB

Joined Apr 28, 2012
697
Well I am at my wits end.
I have been trying to Sort out a system so that I have some quality of life whilst we have these 15 hour daily power cuts.
I made up some LED lights with LED's I imported. (Attached Datasheet)
I used the following on line LED calculator to design the layout and work out the resistors (Only cause I don't know how to make the correct driver)
I made the resistors bigger as I want the LED's to last.
Measuring the current at 12 Volts using my mason power meter it reads 0.06 Amps, 0.7 Watts. I assumed this would be ok.
Well 90% of them have failed within a month. Before I make a fool of myself and blame the LED's I want to understand if this is the problem OR the calculator OR me.
 

#12

Joined Nov 30, 2010
18,224
It looks right.
15 ma per series string, the right amount of voltage across the resistor...
I'm coming around to blaming the LEDs.
 

bertus

Joined Apr 5, 2008
22,270
Hello,

The datasheets tells me that the absolute constant current is 20 mA.
With the 150 Ohms resistor and the lowest voltage given in the datasheet ( 3.0 Volts), you will be at this 20 mA.
Raise the value of the resistor to 180 or even 220 Ohms to be safe.

Bertus
 

Thread Starter

RodneyB

Joined Apr 28, 2012
697
Hello,

The datasheets tells me that the absolute constant current is 20 mA.
With the 150 Ohms resistor and the lowest voltage given in the datasheet ( 3.0 Volts), you will be at this 20 mA.
Raise the value of the resistor to 180 or even 220 Ohms to be safe.

Bertus
Hi

Thanks very much, I will change it and give it a test. Thank you for your help

Rod
 

#12

Joined Nov 30, 2010
18,224
The datasheets tells me that the absolute constant current is 20 mA.
With the 150 Ohms resistor and the lowest voltage given in the datasheet ( 3.0 Volts), you will be at this 20 mA.
But RodneyB measured 60 ma for 4 strings in parallel. :confused:
 
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