I have been testing some blue 5mm LED's from a new manufacturer.
I placed 3 or 4 LED's in series and ran them off a small 33A 12v battery.
Sometimes all three lit up sometimes one of them did not want to light up but flickered a bit.
When the one that flickered was tested in isolation across a 3v lithium coin battery it seemed dead.
What is going on here? Being in series, Vf should not be a huge problem. I tried direct voltage as well as through a 1K resistor, same problem.
I have tried this with 3 different batches of LED's and each batch has this problem.
Same problem with greens but the whites are OK.
Could it be a bad batch of LED's or static
By the way, the final product requires that the LED's are mounted in series and run off this liitle 12v battery sometimes with a resistor in series.
Thanks for the help.