LED beyond rated Current

[h2k]

What happens if you push a LED beyond its max rated current? For example, I found that I could run a LED at 1.0A (but rated at 700mA). It required a pretty large heatsink, but worked fine during testing (about an hour).

Would the life just be shortened? Would the wavelength drift over time? What are the bad things that could happen that did not show up in the bench test?

 

[GreenGiant]

You would most likely just lower the life expectancy, and waste a lot more energy in heat.

Typically they are rated not for their max but for the maximum brightness/efficiency/longevity, for example if you have a 5V 20mA LED you can run it all day long at 9V 50mA and it will be slightly brighter than at 5V, but its going to get hot, and its going to fail in probably half the time it would normally.

 

[h2k]

Thanks for the info. I have a Lux meter so I will see how much improvement I get with running it at 700mA versus 1000mA. If there is a decent payoff, then maybe it is worth it. If the increase is small, it would just be wasteful and require a larger heatsink. Worth having a look at least.

 

[BobK]

LEDs are less efficient at higher currents (because the forward voltage goes up). So you will get less than 42% more light by going from 700mA to 1A.

Bob

 

[(*steve*)]

because the forward voltage goes up

Technically (and perhaps uselessly), it's auger recombination that is responsible.