Lifespan of led grow lights?

3 years I had one, and 2 drivers broke. The light had 2 drivers, but the brand should be using a better driver now. But I got a discount on a new light.

The advertised 50k + hours is dependent on a few things. You'd have to reference each original manufacturer of the diode to see how they are tested and what the longevity curve is based upon. In the case of the lm301 samsung chip, it depends on running at .25watts per chip and 25C at the diode or cooler. Anything hotter will dim faster. This is a "L90" ratings, which mean after 50,000 hours it'll be at least 90% as bright as it was day 1. You can always take a basic measurement under your light -- some fixed position and distance. If that dims to 90% of original reading before 50,000 hours, you know it was running hottter than what the spec sheet said. -- any light meter will work for this, even klux -- proportional intensity.. day 1 is 100%, or the denominator for future measurements. So, even though most advertise a "passive heat sink" .. you should most definitely have some breeze going over it. The high efficacy lights will feel cool to the touch with just a light breeze. Less efficient lights will run hotter / die sooner.

Most of leds are calculated for 50000 hours. At least Samsung good bins have that range.