When we talk about LEDs we talk a lot about about “lifespan” and “cost-over-time returns” but what does that actually mean? If you’re paying £20 on an LED lightbulb, you’ll want to know how long it’s going to last.
The Truth Behind LED Lifespan Estimates
LEDs are quite a new technology (despite being around for over fifty years), and there’s not much of a consensus on what happens past the advertised 25-50,000 hour lifespans – if that’s even ever happened “naturally.” The lifespan of a lightbulb is an average: it means that during the product testing phase, about half the bulbs failed at 25,000-50,000 hours.
Product testing can’t always replicate real-life conditions, however. Streetlights and other outdoor lighting applications might have lifespan requirements higher than that, but otherwise we haven’t really reached them. So all we know is what the manufacturer knows.
But here’s the thing: we’re actually not all that sure what these estimates mean. At the end of that advertised lifespan, the LED isn’t dead; the bulb is giving off about 70% of the light it gave off in the first place.
At 70% brightness, the average person is going to notice that their LED lightbulb less bright. Theoretically, that LED lightbulb you splurged on will continue to shine until it becomes incredibly dim – even to the point of uselessness.
That is, of course, if it doesn’t break first…
LED Failure, Stress Testing, and Where Warranties Come From
There are a lot of electronics inside an LED light bulb. Generally, it’s not usually the diode itself that fails – it’s components like the heat sink, the transformers, the circuit board, and so on.
The product testing phase attempts to replicate the real-world applications for which the bulb will be used, but much more quickly.
For example, the transistors in LEDs can be destroyed by high temperatures, reducing their lifespan even as they are adopted by third-world lighting projects. So products are tested for extreme temperatures as well as thermal shock (by transferring from very hot to very cold environments), which will mostly affect the electronic components.
Mechanical stress testing checks for failure when the luminaire is subjected to intense vibration or shock, which is useful for automotive applications. Since these vibrations amount to repeated shocks and jolts to the light, like being dropped over and over again, it’s important to know.
And if the product fails too quickly, it’s sent back to the drawing board. Manufacturers will define “too quickly” differently – this is how warranties are set. Thanks to extreme stress testing, a manufacturer can
say that their product can be reasonably expected to last five or seven or however many years.
So, there we have it: LEDs will last a long time unless something goes wrong, and we don’t really know how long they’ll last. We’re sorry that’s not a more conclusive answer, but it’s what we have.
Readers: have you ever had an LED lightbulb that died on you before the warranty expired? And if so: how did that happen?