LS3 Update

Well Christmas and the new year are fast approaching. And with it the holiday break in manufacturing that our contractors take. Most of our current projects are planned for January now since there is not many work days left in this month.

The LS3 is still waiting on LEDs from Lumileds. We have managed to scrounge together a small number of production revision units, enough to do some more testing. One thing we are finding is the 2watt level simply is too much for a single 123 cell. The system is just too inefficient at that current consumption. Our engineer tweaked the circuit and figured that we would get a better mix of perfomance if we adjusted the power level to 1.5watts to the LED. This also causes the circuit to regulate better meaning that the 6v pack now increases the run time instead of increasing the power level.

There is still more testing to do but I feel good about this power level for the LS3. Run time has gone from less than a 1hr at 2 watts to over 1.5 hours at 1.5watts. Similiar run time to the LS1 and LS2 infact.

Another good reason to dial the power down a bit is the short life span of the 5watters. When we first announced the LS3, we thought the part would have a standard 100,000 hr lifespan. But now Lumileds has changed the spec to 500 hours. This can be extended by lowering the heat experienced by the part. This is achieved by a combination of derating the power level and using a great heatsink.

The original design goal of the LS3 remains the same. We hope to replace the LS1 and LS2. The delivered specs should be the same run time as the LS1/LS2, same package size and weight, same battery (with an option for longer run time) all while delivering more light through greater efficiency.

I anticipate that one of the biggest challenges of the LS3 while be getting sufficient quality emitters from Lumileds. As a result, we will continue to offer either the LS1 or LS2 (which ever is brighter) until then.

Peter Gransee

Peter, when can we look forward to unblemished LS2s?

Peter,
In the test unit that is running 1.5w,How much brighter is it than the brightest Ls 1w?
Thank you for the update

Derating seems like it would be less of an issue if lumileds could reliably deliver high quality bins. I would think that even at 1.5 watts, there is not a person here that would claim the x bin to be too dim. I doubt there are many if any x's out there and that lumileds prefered client base would get them. It took a while for s rank nichias and a stable supply of high bin letter 5 watters will probably take longer.

Thanks for the update, it helps buyers plan their next purchase. 1.5 watts is disappointing, but performance compromises and basic physics rules. Hopefully someday, the full 2 watts will be realised through better electronics or batteries.

For now, I'm more concerned for the LS2. After reading some posts from others who have just recieved the LS2-2nd2, I'm really concerned about the brightness. I've owned and tested enought LED lights (of all types) to know that no two are usually the same, however I do have concerns about the reported brightness of some of these LS2's coming out the door. It's one thing for people to find them "a bit brighter" or "maybe the same", but after all the hype of these things going to be 50% brighter and now to hear that some are dimmer that the LS1, it really puzzles me.

With the release of the LS2, we're now talking some serious cash, not that $50, $60 and $110 was not serious, but now the LS2 reaches a new level. These major swings in inconsistancies have to be resolve.

All I ask is that you DO NOT release the LS2-1sts, until all issues have been resolved. There's nothing that will bother me more than to buy 3 or 4 of these and find out of a known problem or that a new internal design change was made. Thanks Peter.

Nobody asked me for my 2 cents but I'm going to throw it out anyway. I have no intent of offense but let the chips fall where they may.

It seems the key element in discussion is brightness and not luminous output. The 1 watt HD LED when coupled with the standard optic will have a tighter beam pattern with a square die image as compared to the low dome. Two LED's of equal luminous out put, one LD and one HD, will have beams where the HD is measurably brighter in lux in the hot spot. I believe this is where the 50% brighter comes from. Unfortunately, this is predicated on the flux ranking of the LED and a Q low dome will likely have a brighter reading than a N high dome.

In my humble opinion, the merit of the LS2 is not in the LED used but the constant current driver as well as the new bezel design and assembly which presumably can be made waterproof. To put the future of the LS2 in the hands of high flux HD's and their availability is certainly taking the control out of Arc's realm. It will be a difficult task to provide a brighter LS2 to someone who already possesses a high flux LS of previous version. I fear that Peter has raised the bar to high here, given the nature of the beast (Luxeon).

In regards to the 5 W luxeon, in an underdriven condition, I suspect that the flux will be demonstrably higher than the typical flux of a 1 W driven at, or slightly over spec. However, if the NX05 optic is used, the beam of the 5w will be much more of a flood and any brightness measurements in the hot spot will likely be higher for a 1 Watt. If brightness, as measured by a light meter, in the center of the beam, is the only criteria, the LS3 will lose out to its predecessors, IMHO. One additional factor to consider with the 5 W is that as you underdrive it, there is a color shift in the light; the color temp goes down. For many of us, this is not desirable; especially if the color rank is low to begin with.

Contrary to how it may appear, I like Peter and Arc and hope for great success for this company. I would hope to be proven wrong in my assessments here. However, I am concerned with the expectations expressed and the path of Arc progression as I understand it from these recent posts. I guess I hope Peter will lower his standards to embrace the materials currently available and reduce his expectations and claims to an attainable level. If not, I suspect that whatever the version being offered, it will likely be denoted as a "second".

- Don

Isn't 1.5w mean it's being driven at 500mA?
If so, how would the 5W be brighter than the 1 watter luxeons driven at 500mA that you made in the past?

Peter,
Thanks for the update.
I for one am skipping the LS2, and will wait for the LS3. With all the recent postings, I don't think I am missing much, with a couple of SLS1 I think I can wait. I would rather see them(Lumiled) get the lifespan back up to 100,000 hours. At 1000hr(last MTBF I heard), divide by 24 and we see 41.7 days, or 667 batteries @ 1.5hr/battery. The day count looks bad, but the battery count looks good. It makes the LED good for Flashlights but I think the lifespan limits its widespread acceptence/use in other applications. Well, that's my 3 cents.
And p.s. Merry Christmas!
Ting

Originally posted by CiTY:
Peter,
Thanks for the update.
I for one am skipping the LS2, and will wait for the LS3. With all the recent postings, I don't think I am missing much, with a couple of SLS1 I think I can wait. I would rather see them(Lumiled) get the lifespan back up to 100,000 hours. At 1000hr(last MTBF I heard), divide by 24 and we see 41.7 days, or 667 batteries @ 1.5hr/battery. The day count looks bad, but the battery count looks good. It makes the LED good for Flashlights but I think the lifespan limits its widespread acceptence/use in other applications. Well, that's my 3 cents.
And p.s. Merry Christmas!

Ting

Click to expand...

<font size="2" face="Verdana, Arial">It should be noted that the MTBF given should be for a unit driven to spec, under driven would probably see a much longer lifespan. Though I too am hoping they get it back up there.

Sean,

If the Vf of the LED is 6.8, then the current for 1.5 watts would be 220 mA if my math serves me right.

Incidentally, Lumiled is now calling the 5W's a 1000 hour LED, for what it's worth.

- Don

Yes, lowering the tempurature like we do does have a dramatic effect on the lifespan of the device.

Peter Gransee

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)

Okay here's my poor attempt in trying to understand an underdriven 5W Luxeon.

A while back, when the 5mm Nichia LEDs were still popular, people discussed this very same principal. "Will light output be greater if you overdrive one LED, or if you drive 3-4 for of the same LED at spec power levels?"

I think the answer was, you'd get better performance and light output by driving 3-4 LEDs at spec power levels. I THINK. If i'm wrong correct me and disregard this post.

But if this is a correct statement, then the 5W Lexeon LED is the same as 3-4 1W Luxeon LEDs....right? Well...that's what i think, considering it's basically 4 1W dies in one package.

Anyway...if this is true for regular LEDS, i don't see why it would be different for the 5W LED.

LEDagent, I remember that discussion

But, as you mentioned, the nichias were driven at spec and were all parts of the same grade and quality - be they the spec-driven ones, or overdriven. And those were discrete LEDs, each with their own leadframes and bodies..etc.

The luxeon 5W and 1W in the LS3 case pose a different challenge in the sense that the 5W is *underdriven*, and quite significantly so, I might add. Of course, there is also the huge lifespan gap to consider and the manufacturer's reasons to go with a particular methodology or product philosophy.

I brought up the hypothesis of an overdriven 1W luxeon for the LS3 because I'm hoping folks can compare the rationale for going either way. Of course, opinions and mileage will vary from person to person.

Peter,you stated above that the LS3 running at 2watts is just to much for a single 123.What about offering the Ls3 in 2x123 and run it at 2-3 watts until it can be made to run more efficient.
Or , offer both the 1x123 @ 1.5 watts and a 2x123 @ 2-3 watts.I am thinking that we might start seeing a bunch of greenies at 1.5 watts.I know that you already have plans to make a 2x123,but I think that was for longer run time??.Maybe by tweaking the circuit you can get good run time and a wow factor of light with the 2x123.

Yes, we looked at several variations. The circuit is an excellent example of Wayne's genius. Even so, it can't do everything-yet. When we turned up the 6v power, the circuit also tried the same thing with the 3v pack. Normal. Problem is trying to draw 3watts from a single 123 ends up being a inefficient mess. I asked our engineer to optomize the circuit for the single 123 pack since that is the preferred pack for our goals. 1.5watt is the maximum ideal power. What happens then with the 6v pack is you get a much longer run time, over 5 hours is the projection.

I would much rather drive a 5W at 1.5w then a 1W at the same power. The idea here is light density.

Peter Gransee

I like the 5 hour projected run time.

will this lowering of wattage have a bad impact on the color-balance?

Originally posted by L.E.D.:
will this lowering of wattage have a bad impact on the color-balance?

Click to expand...

<font size="2" face="Verdana, Arial">Good question. There was some discussion on this in another thread. I think it was mentioned that a direct current reduction resulted in color shifts, but a PWM solution should be OK.

Hmmm - does that indicate the possibility now that the LS3 might have to couple a PWM component to maintain white color fidelity?

Or might we end up with slightly green underdriven 5-watters?

I noticed that my Q1 1-watters are at their most supreme greenness when significantly underdriven, but whiten up pleasingly when pushed hard. This is partially why I suggested the overdriven 1W idea - it helps the allowance of use of good-flux-but-lower-color-temp luxeons, instead of hanging at the mercy of Lumileds Wheel Of Fortune.

It may be oversimplifying things a little, but I do believe that its easier and cheaper to achieve an acceptable intensity of white by overdriving a 1W (even a bad one) than underdriving a good 5W.

That said, 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.