LS3 Update

[Sean]

Originally posted by hotfoot:
Y'know, at this point, which would you choose?

- LS3 using a costly 5W underdriven @ 1.5W lasting 1000+X hours

- LS3 using a cheaper 1W overdriven to, say, 2W lasting 100,000-X hours

For me, I'd take the 2nd option and hope the cost difference is passed on the consumer as a price reduction and/or enhanced flashlight features overall.

(Edit: PS... a 5W luxeon costs about 3x that of a 1W)

<font size="2" face="Verdana, Arial">If you drive a 1W luxeon to 2W, there's no way in hell it's going to last 100,000 hours! To get the maximum life, you would have to drive the 1W at 350mA. I didn't even think luxeons were rated at 100,000 hours anyway. I thought its was 50,000. Might be wrong about that one.

 

[hotfoot]

Sean,

Originally posted by Sean:
If you drive a 1W luxeon to 2W, there's no way in hell it's going to last 100,000 hours!

<font size="2" face="Verdana, Arial">C'mon, buddy - ya didn't think I'd make THAT mistake, right?

Look at my post again - you'll see that I put the life down as (100,000-X) hours, where X is the as-yet-unknown number of hours where the life of the overdriven luxeon is shortened by.

BTW, 2W really isn't such a far-fetched notion for something like the Arc LS. Think about it -
driving a luxeon 3.3V@500ma (like in some hybrids) already yields you a 1.65W Arc LS. Even driven at spec, a 1W luxeon is really somewhere from 1.1W to 1.25W. A 2W Arc LS would be driving its LED to about 650ma. Some folks are successfully driving their (well-heatsinked) luxeons to 1A and beyond even.

Originally posted by Sean:
I didn't even think luxeons were rated at 100,000 hours anyway. I thought its was 50,000. Might be wrong about that one.

<font size="2" face="Verdana, Arial">Their datasheets state 100K hrs for the 1W, so, lets say we take it with a pinch of salt and cut that in half to 50K, and for fun's sake, lets divide that by 10 because we're overdriving the poor thing - that gives us 5K hours! That's still 5 times longer-lasting than a 1000hr-rated luxeon 5W portable.

I'd say its worth the gamble, particularly since the part is cheaper already to begin with.

Does any of this make sense?

Edit: The intention of driving to spec the 1W LED in the first Arc LSs, I believe, was to stick as closely as possible to Lumileds recommended specs - thus giving you the best likelihood the LED will survive 100K hrs. The reason why folks here want a 5W LS is because its supposed to be BRIGHTER. But, at 1000+X hours, its nowhere near the 100K mark of the original LS, so why bother trying to preserve even that feature by underdriving it to only 1.5W if the brightness is not at least equal to that of a properly-managed overdriven 1-watter?

Take a look at Lambda's 1W SE Illuminator - does it rock or what? It'd be kinda funny if a costly new 5W Arc LS lost out to one of Lambda's mods for brightness - and *still* didn't even manage to match operating lifetime!

 

[Willmore]

Is this light going to be useable with a 2AA pack? NiMH cells (a pair of them) should have no problem supplying 2-3W--for a short time. Certainly better than a 123 cell can.

 

[B@rt]

Originally posted by hotfoot:
I truly respect Arc and Peter for sticking to the engineering high road instead of succumbing to some of the temptations to overdrive. I just hope that there's enough sustenance on that very road to keep them going to where they can finally triumph over these problems they are having.

<font size="2" face="Verdana, Arial">I could not agree more... I do feel however that sharing can be costly...

Peter, I really like your straightforwardness (phew, long word ... did I spell it right? does it even exist?

), but, would it not be better to keep R&D out of the picture?

For sure you keep us drewling

, but sharing development progress (and failures), IMHO, is not a nescessity(?), please bear in mind there are less friendly people (

)reading these boards too...

 

[Klaus]

Agree on all the yahoos to Peters work.

But let me throw in my 2 €cents

Looking at the single 123´s problem sustaining the current draw effectively (which might be partly due to the very high voltage difference from 3V or less under load to the average 6-7V the 5W LS needs) why not slightly modify the master plan - I understand that this might sacrify at least two of Peters goals which are "small & bright" or "light density" and "kiss" in regards to ARCs overall operation.

But here we go:

Keep the ARC LS2 in the pipeline using high-flux 1W LS HD parts (Q or better) for the "firsts" at ~400ma as right now - with Lumileds hopefully getting better yields next year this might not be too unrealistic - those "Q" LS are 30 to 39 lumens and should be well within or close to the flux level a 5W device at 1.5W might be putting out - and having a better throwing beam as well.

The ARC LS3 using the 5W Luxeon will only be offered using the 2X123 battery pack and having the voltage of 2 123´s available and the circuit tuned for that Vin should make the circuit operate much happier and more efficient - it should be at around the 3W originally planned - or maybe even a bit more given the tuning for the 2 cells which could result in better efficiency.

Drawback would be two products at the same time which Peter was trying to prevent but which at least to me seems to be the smaller problem than what seems to be only possible following the "one product fits all" approach which in my eyes would possibly result in catastrophic failure for ARC - because as I see this scenario evolve ARC would end up with a 200 USD light not much brighter if at all than some 20-50USD plain vanilla 1W LS job.

And the great "light density" would still be there using the 5Watter head in the still possible but not recommended 1 x 123 config.

So for me the best solution is pretty simple - and as an added benefit this would not only be the best for ARC (at least as I see it) but also what most CPF-ers where asking Peter for anyway - keeping the LS2 alive when the LS3 comes along.

Klaus

 

[W4DIZ]

At this point in the game,I would have to agree with Klaus.Useing 2x123 for the LS3,and keeping the high flux 1w ls hd LS2.

 

[dark star]

I still hope for a Cyan LS3 (as far as I know the cyan/colored 5W Luxeons are great-super bright,long life and of course no tint variation-the 5W Cyan I have is wonderful). Also I would like to see the LS3 use AA NiMH cells - I would use the light for 1/2 to one hour at a time-hiking-biking. The 5W Cyan is great for biking, but the 5 D cells are too dang heavy(the run time is like forever).