The diode reached 123h+ over the weekend, uploading the latest degradation plots..
123h P/I Plot:
123h Efficiency Plot:
The graphs now only show the plots that are evenly spread appart in time...
Diode Stats:
Ith = 36mA (no change here)
Po @ 300mA = 317mW (89.04% of initial)
Slope Efficiency = 1.204mW / mA
Actual Efficiency = 17.95% Peak / 17.72 Avg.
The diode dropped under 90% of initial power quite a bit sooner than predicted, so the degradation clearly is speeding up. Altho it did speed up once before, but then slowed back down again.
Only thing i still don't understand is why it didn't show a difference from 90 to 100h, while a big difference is noticable after an additional 20h.
Something similar happened once before (don't remember at which point).
One interesting thing to notice is, that the first 30h caused pretty much the same power drop, as the 90h after that.
This diode most likelly won't last much longer. If it dies in under 150h it would answer the original question - what current can these diodes survive for 100-150h (of course it will vary from one to another and we can't really afford to kill enough to get to the averages).
One thing is for sure at this point - the 8x's are WAY tougher than i ever thought possible!
I feared 300mA might proove to be too much - i was worried i would have to give everyone bad news, but in this case i couldn't possibly be happier prooving myself wrong! :evil:
So we are definitelly pushing forward with the next one, but i think it would be best to chose a current, where the results of the two experiments are still possible to correlate in some way.
Ideally we would find a power where they last approximatelly 50h, which is still somewhat reliable for those willing to take the extra risk.
But if we go too high and get 20h or less as a result, that would not be good, because at those currents survivability will vary anywhere from 1-20h - the higher you go, the less the results of one diode will be comparable to another (some can pop instantly, others can last a surprising amount of time - let's just hope this is not what happened here - another reason i don't want to go too far with the second one, if done right, it could reaffirm the results of the first one, as well as provide answers about higher currents - how fast the life drops, as current is increased).
Does anyone know which currents they start dying at unpredictably. I heard there were several losses at 360mA+?
As i said, the higher the current, the more the results will vary from one diode to another - if we go too high the diode could die prematurelly OR it could last due to pure chance and provide a fake sense of safety at that current.
In my oppinion, it would be best to test 330mA next.. That would allow comparing what a difference in lifetime the higher current caused, perhaps correlate the results of the two in some way, but everyone who donated has a word in this of course...
Hopefully we come to an agreement about the second current, which will provide information useful to everyone.
P.S. There is one question that really bugs the hell out of me. How long a high efficiency diode would survive the same current as this low efficiency one.
I'm almost considering sacrificing one of the two 8x's i got for myself. I'm thinking of offering one of my personal lasers for sale, and if it gets a buyer, i think i'll kill one 8x diode out of my own pocket, to confirm the first current, (or the second one, IF the second current should seem "reliable" enough).
I badly want to see how much of a "health indicator" efficiency really is with these diodes!