I’ve heard that PWM can extend the life of an emitter. However, I don’t know how much extra life to expect, or whether current-regulated constant output has a similar effect.
So, can anyone here enlighten me?
Like, if a LED is rated at 50,000 hours and it’s running with a driver using PWM at a duty cycle of 10%, does that mean it’ll probably last for 500,000 hours? Or does it work a different way?
If that same LED is running with a current-regulated constant output of 10% its maximum, does it have a similar effect, or is it still just 50,000 hours?
I’d imagine it probably has more to do with heat than with actual runtime, so the torch’s thermal dissipation capabilities might be more relevant, but I’m just guessing.
And, of course, individual LEDs vary quite a bit… one might last only 500 hours while another lasts 500,000. But I’d still like to know what happens in the average case.
There was a thread with this in a bit back, I think the conclusion was constant current was better for emitter life. One thing to think about is how long 50000 or even 500000 hours is in years, then apply it to the use of one torch….
Oh, definitely. It’s hard to reach that 50,000 hour limit. I’ll probably hit it on some of my interior lighting, but it’s highly unlikely I’ll ever run out of emitter lifespan even on my favorite EDC torch.
If I were to use interior lighting 12 hours per day, it would take 11 years to reach 50,000 hours. That may actually happen eventually. However, even my favorite Zebralight gets less than 3 hours of use per day, which means it should last for at least 45 years… So I’ll probably wear out the switch first or upgrade to a new EDC. And that’s 45 years on the brightest mode, while I normally use less than 10 lumens.
So, you’re completely correct. The life span is effectively infinite for typical uses, so it’s probably not worth bothering with the details of exactly how infinite it is. I still find it interesting to think about though.
With technology advancing at such a furious pace, you may not want to keep an LED light source for 11 years. Can you imagine still using the cell phone you had 11 years ago?
Maybe, maybe not. Light bulbs don’t really improve much over time aside from getting more efficient.
However, if they made LED light bulbs with more features, I’d totally get a bunch. Like, flip the light switch on and it comes on in low, flip the switch off and back on quickly to advance to medium, then again for high. I could totally dig that.
That looks neat… though I don’t care much about the color options and I’d hate to have to control it with a phone. I was thinking more along the lines of a Cree MK-R or maybe a few smaller LEDs with a driver controlled by an on/off switch like what a reverse clicky has, but controlled instead via a wall switch. Run at like 1.8 lumens, 18, 180, or 1800, depending on how many times the light switch was flipped on. Or perhaps at 30, 600, or 1800, with an extra 0.1lm mode for nightlight use. Even better if a bunch of them could be mounted on the wall as small uplights for indirect lighting, all chained together.
I don’t really know what would be best, but it seems like it could be done pretty cheaply in much the same way that budget torches are made, with a similar interface.
Discussion relating to lifespan of LED was discussed. The experts suggested that the other factors of the torches are more concerning than lifespan of led.