Further Arc LS testing (batteries are weakest link)

[geepondy]

I have been futher testing the Arc LS tonight. I was inspired after reading of Surefire bulb failures and wanted to see how the LS would hold up with a bit of abusive testing. So I did a little bit of aka Craig testing and threw the flashlight around the room a bit. The light was installed with the double AA battery compartment with Eveready lithium AA L91 batteries. The light survived mild tosses of up to ten feet or so, landing on the low pile carpeting. But when I threw it against the door and not with an overly excessive force, the light suddenly went out. Upon analysis, both of the AA battery negative sides were indented. When installed with a new set of batteries, the light worked fine. Comparing new L91 lithium batteries with my standard now extinct Costco Kirkland AA's, the Eveready batteries have a flat negative terminal end whereas the Kirkland's are raised somewhat.

What I have drawn from conclusion further reinforces my opinion that I do not like the activating mechanism of a flashlight by simply turning on the head. If this would have been a spring loaded battery compartment with some sort of a real switch, I think the light would have survived even with slightly compressed batteries. I would equate my throwing the light against the door with maybe a five or six foot drop onto concrete and while the light mechanism held up just fine, there is very little compensation for battery differentials.

 

[Gransee]

So after tossing the light around the light went out. I understand that. But were you then not able to tighten it down further and cause it work again or did it not want to come on at all? This is with the same set of batteries.

Peter

 

[geepondy]

No, it would not come on even after tightening it down further and with the same set of batteries. Did some more observations this morning. One of cells from the same set of batteries works in the single A compartment, the other one doesn't. The one that doesn't is just a millimeter or so shorter and it looks like the postive nipple may not sit quite as high. Very little differences but enough to stop it from working. I also found that I may have contributed to the indentation of the negative end of the batteries by overtightening the head as I see now, my newly installed batteries (same type) also have an indentation although the light works fine. As mentioned, the L91's have a very flat negative terminal.

I'm really surprised there's not a small spring or some other damping mechanism to buffer the battery against the metal contact points. I do not use brute force to tighten down the head and evidently it doesn't take much pressure to damage the batteries. Maybe better shock isolation aka Surefire, might be worth investigating in future Arc revisions. I have low confidence now that the light would survive a drop test of any sufficient height onto a hard surface.

 

[Gransee]

Respectfully,

The purpose of the Arc-LS foam battery retainer is to protect the PCB and the battery. The battery contacts the retainer, which absorbs some of the energy before the battery makes contact with the PCB. This is the same foam that Orbital Sciences uses to protect their electronics from the vibration of launch.

The new retainer design further improves on this by using a 2-stage foam with a denser second stage.

The AA cells, especially some brands, will compress with normal usage and over time. The 123 cell is more hardy in this mode though because it weighs less and has a larger contact surface area.

A spring against the negative contact only helps if the light falls tail first. The Arc-LS in all configurations has the CG forward so the light will strike headfirst. This is true for most lights btw, I checked my 2AA mag and my E1 and they have their CG forward, test it for yourself. A shock absorber only helps if is placed in line with the direction of movement- which the Arc-LS retainer happens to be. Try the drop test without the retainer and you see the difference it makes.

One thing I would like to add in the future is possibly thicker foam up front with a low friction layer to reduce turning drag and wear.

It is tricky to spring the positive contact of a cell without shorting the light to ground. That is probably why most manufactures place the spring at the rear, which provides positive force for electrical contact but doesn't really help shock absorption from being dropped.

Another use for the spring is to protect the cells from overtightening. This must be used in conjuction with a switch design, otherwise the light is always on.

But adding a switch and spring will only hurt the battery more in a fall (extra weight) compared to a good retainer design.

I believe in the retainer design because it provides maximum protect from falls, some protection against overtightening, makes the light smaller, lighter, less expensive, more reliable (less electrical contacts to oxidize, less moving parts), it also provides polarity protection (reversed batteries are the leading cause of flashlight explosions), light module protection, partial on flicker protection, and reduces rattle (even more so than a spring does).

If they didn't already figure it out for themselves, now our competitors know why we use the foam retainer. I could have just said, "trust me, the retainer is better". But somehow I think you would prefer that I tell you exactly why.

Peter Gransee

 

[**DONOTDELETE**]

(oops, edited! got it reversed the first time, sorry)--I had the same prob. with a single aa battery holder when using the foam retainer. A particular brand of nimh battery goes on at the exact moment of the threads reaching the end of their travel; bottoming out..There is no play at all during which the light stays lit. The slightest pressure in the off direction puts out the light..the problem disappears when using the head without the retainer . The problem also disappears when using a lithium aa - I haven't measured but are they slightly longer??
I am also puzzled as to why not using the retainer seems to solve aforementioned problem..something to do with centering the battery perhaps? Or maybe the two illuminator heads (ser #s 038 and 164) are slightly different dimensions?

 

[geepondy]

Peter, thanks for the explanation. I will continue to support Arc and it's future developements. Are there any plans for a switch mechanism in future Arc products? For the Arc AAA, I had stated you should mimic the Infinity in physical design. The Arc AAA now has a better design then the Infinity, IMO (no battery rattle for one thing). For the Arc LS or a similar product I would recommend mimicing the Surefire E2. You won't beat it but I would love to see an Arc with a tail cap switch similar to the E2. Push on for momentary light, twist for constant on.

I won't be throwing my LS anymore. I'll accept it the way it is!

 

[Gransee]

Thanks Geepondy! If you find the light is getting dropped a lot and the batteries keep getting squashed, try the 123 pack. It is the toughest of all three packs. The 2AA is the heaviest and the 1AA is in the middle. Basically the heavier the battery, the more likely it will damage itself.

Just another factor you may consider when selecting which power pack works best for you.

Tail switch. I have looked at this problem off and on for over 6 months now. The most durable/cost ratio is to put it in the tail but that extends the length which is against my religion it seems. Logic controlled switches and SPST latching push buttons have some disadvantages. Mometary is the most reliable but then you need some other mechanism to provide the constant on. The plus side to that requirement is the constant on can also provide the lockout feature.

So it's still in the works.

Peter

 

[lightlover]

Thank you - that's very interesting Mr. Gransee, educational indeed. So many factors to ponder upon.

Not quite like Ken B might say
"It's only a Flashlight ... "

lightlover

 

[geepondy]

I hopefully won't be dropping the LS that much. I just did this test for curiosities sake. Mostly the light will be used around the house but I do hike in the summertime and will include the LS in the backpack. I have not yet, and hopefully will not encounter any overnight emergency stays that requires the use of a flashlight. But if so, I will have the LS, LE and Infinity so I should be covered.

I really like the double AA battery pack the best. With lithiums it provides the brightest light and is easily carried and feels very comfortable in the hand. I can see the advantages of the 123 pack but unless needed to carry in a pant's pocket, is uncomfortable to hold for me. Much why I prefer the E2 to the E1 for the same reason, brightness aside. I can see why the single AA pack might appeal to people who needed enough light for night time travel and needed the absolute best efficiency but I don't fit in that category. I will use the 123 battery pack at times but probably will never use the single AA pack.

So maybe I should retitle the thread "What is your favorite Arc LS battery pack and why?"

 

[vcal]

I don't know if you have the 1-AA barrel or not, but if you do, you can use (with a simple spacer), 2-1/3 AA Nimh cells in it to make that light into a real pocket rocket for it's size.

It'll still be a little underpowered, but it should beat the pants off of a single AA!
When I get one, that's what I'm gonna do--for brightness/size ratio-not battery longevity..

 

[**DONOTDELETE**]

To answer the question: what's your favorite ARC-LS battery compartment...

Well, based on handling, ergonomics, and aesthetics (same width throughout), it would be the 1 AA compartment. It's big enough to get around the handling problems of the 123 compartment, but much smaller than the 2 AA. Unfortunately, it's considerably dimmer.

The 2 AA is good for around the house use, but doesn't carry as well. I put two "dead" regular AAs (former device didn't work anymore, and the self test strip on the batteries said they were dead) into it, and it was almost as bright as two lithium AAs. That's impressive.

The 123 is great for carriability, but is hard to turn on/off one handed. I did find that holding it overhand (ala tactical), as if you were going to use a tailswitch to activate it, and using your thumb to push the lanyard fin, works pretty well. I'm going to try carrying around this one, and see if the battery cost becomes prohibitive.

I may have to try vcal's suggestion about the 2 1/3 AA Nimh cells.
-----------------------
Mini review of my impression of the ARC-LS, which arrived on Friday, 1/25/02 from TTS. It's #058.

I like it; the beam quality is excellent for almost any normal use. Yes, there is an irregular yellowish corona at short distances, but it doesn't significantly affect usability. The color is a nice white, much whiter than even the ARC-LE, and pretty uniform starting around 3 feet or further away.

All three compartments worked for me, though the 123 seemed to work better with Duracells than with energizer e2 123s (might just have been break-in effects).

The overall quality is very good; the hard anodization is nicely done, and almost completely greyish, with much less olive in it than with the ARC-LE (I suspect the much less aggressive knurling has something to do with that). I even like the knurling, though a little more probably wouldn't hurt. The threads (after lubing and breaking in a little) are pretty smooth.

The only thing that mildly annoyed me was the amount of lint visible behind the lens. But after thinking about it, I've convinced myself it helps diffuse the beam...

 

[**DONOTDELETE**]

One comment I forgot to include:

Regarding beam quality, I prefer the ARC-LS's white center with (at close range) irregular yellow halo to the more typical LED blue hotspot. I'd rather have good color in the center, for obvious reasons.

 

[**DONOTDELETE**]

Peter,
you considered only putting a spring at the positive end -- what about a spring at the negative end? Would it be too difficult to get it sprung just right so that the battery wouldn't be pushed into contact with the positive terminal when in the off position? Maybe a spring in the negative end, in conjunction with a slightly longer aa holder would fix it?

 

[JollyRoger]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Ted the Led:
well it seems the aa problem has possible been solved with the new retainer..
Would using a different form of the cobalt/gold material be possible? I was thinking of the screen type material, with the foam retainer material underneath it, to absorb the pressure of the battery when turned on...?...?<HR></BLOCKQUOTE>


YES! It seems like the perfect solution to those who are afraid of damaging the precious gold/cobalt contact in the head of the ARC LS. I've thought about this.

You know, even perhaps putting just a really small piece of the mesh-type conductive cushiony material in either the head or perhaps the base (well, I guess the little nipple sticking out of the base kind of hinders this).

Does anyone know where to buy this mesh-type material? I have some from one of my older Princeton Tec 40's, but now they don't use the mesh anymore...

 

[**DONOTDELETE**]

well it seems the aa problem has possibly been solved with the new retainer..
Would using a different form of the cobalt/gold material be possible? I was thinking of the screen type material, with the foam retainer material underneath it, to absorb the pressure of the battery when turned on...?...?