Going back to Metal Halides from LEDs

[sfsuphysics]

It depends a lot on the LED and the fixture.
A good quality LED, driven well below max current, with a proper heat sink, will last an absurdly long time.

Makes me wonder if the lifespans that every manufacturer throws out at you is based on these idealized specs (and maybe in a lab environment too just for the final kick in the nuts). Where as there aren't many fixtures out there that runs at "idealized" current, and most all of them run at or near max current. While sure they do have good cooling available I think it's best to assume your fixtures are going to be similar to CFL bulbs for your home that supposedly last 5+ years before needing to be changed (based off 3hrs a lighting a day) and yes the ones in a environment (bathroom) that aren't on nearly as long do die a lot quicker

 

[rygh]

Makes me wonder if the lifespans that every manufacturer throws out at you is based on these idealized specs (and maybe in a lab environment too just for the final kick in the nuts). Where as there aren't many fixtures out there that runs at "idealized" current, and most all of them run at or near max current. While sure they do have good cooling available I think it's best to assume your fixtures are going to be similar to CFL bulbs for your home that supposedly last 5+ years before needing to be changed (based off 3hrs a lighting a day) and yes the ones in a environment (bathroom) that aren't on nearly as long do die a lot quicker

From datasheet:
"Philips Lumileds projects that LUXEON Rebel products will deliver, on average, 70% lumen maintenance (L70) at 50,000 hours of operation at a forward current of up to 700 mA. This projection is based on constant current operation with junction temperature maintained at or below 135°C."
That is at max current, and pretty warm, so a pretty reasonable spec.
But then Phillips is not some cheap import. I doubt you will even find the data for some LEDs.

 

[sfsuphysics]

700mA is max spec? do the Rebels have less overhead than the Crees? Because I know Crees can be pushed well beyond 700mA (unless it's red)

That said... at 10 hours a day, that's over 13 years which isn't half bad.

If I had to put a finger on the weak point though it would be the electronics, either the traces, the PSU, or something other than the diode.

 

[rygh]

700mA is max spec? do the Rebels have less overhead than the Crees? Because I know Crees can be pushed well beyond 700mA (unless it's red)

That said... at 10 hours a day, that's over 13 years which isn't half bad.

If I had to put a finger on the weak point though it would be the electronics, either the traces, the PSU, or something other than the diode.

Absolute max is 1,000 mA, so you can push them higher, and some fixtures might.
But pretty much all the docs say 700 mA.

Traces are usually fine except for DIY soldering or wire choice mistakes.

Power supply can be very much a weak point. Especially on PAR38 type fixtures where they really jamb things tight.