LED Life when overrun

LEDs aren't normally connected directly to a voltage source so your expression "Cause of over-run, higher voltage than 3.3v" is a little odd.

To connect an LED to a battery with voltage Vbat use a resister in series..

R= (Vbat-Vled)/I

example

Vbat = 12V Vled = 3.3V I=20mA

then

R = (12-3.3)/0.02 = 435 (or the nearest standard value to this).

I know, I know, but I prefer the higher light output, when run at higher voltage, and am prepared to sacrifice most of 100,000 hours life to achieve this.

I do not need the leds to function after I'm dead !!

So, higher consumption, brighter output, lower life, within limits, any sugestions as to quantative analysis, no other response needed !!

higher

any

Basically (much like an incandescent bulb) slightly greater perceived brightness will result in a dramatically shortened life. If you insist upon exceeding the specs, you will be "rewarded" with a mediocre increases in brightness followed by dimming of the bulb (deteriorating loss of efficiency) and eventual bulb failure.

I suggest you do your own experiments. Start by doubling current over the max spec and then work your way down. You won't have to wait anywhere near 100,000 hours for quantitative results. ;-)

Understand that LED's are not voltage operated devices, they are current operated. You should never apply a voltage without some kind of resistance to limit the current.

Give these people a try, they know a lot about LED's and lights in general.

This page has a graph for the "Half life time of Luminous Intensity" vs Junction temperature....

Quote: Regarding the luminous intensity (IV) which is the main characteristic of LEDs, the half-life (time when the luminous intensity has been reduced to 50% of the initial value) obtained from the accelerated operating life test, is estimated as shown in Figure 3-2.