Update: AAA intermittant operation

Merri and I just got back in Phoenix from the SS tonight. I am catching up with the CPF threads and notice that there still intermittant problems with the AAA. I am going to inquire on this tomorrow starting with a review of warranty returns then onto indepth testing of products on the shelf and finally on to a fix. I was talking to Henry about this last night and we both agree that we will probably have to use a different chip in the AAA. The manufacturer of the DC/DC chip changed where it was manufactured and something has changed with how the chip works. It appears to be in spec but no longer works reliably in our circuit. When we originally detected this we tested the light and found it sometimes would not turn on. We added another capacitor to the circuit and this fixed all the test units. But we are still getting complaints and I don't think these are old stock. Our current test consists of 50 turn on/off cycles with the light being placed in the freezer and then in hot water to stress the circuit. The test I am going to run tomorrow will consist of 20 production units hot/cold and 50 cycles. If they all pass 50 cycles, we will increase it to 100 cycles (we use gloves to keep our fingerprints attached). I expect to find a problem and it will probably be with the chip. I have asked Henry to prepare to put our other engineering projects on hold and redesign the circuit in the AAA/AA with another chip. The head will likely need to be changed as well to make room for the larger chip. If there is a problem with the current design, I will freeze or cancel all orders for it and sell the stock as "seconds". We will either refund or replace previous models that exhibit this defect.

I will keep you posted.

Peter

Oh yuck Peter. Thanks for keeping us informed, and best of luck with it. Have you asked the chip vendor for help?

My EDC AAA regularly shows the problem when I use a particular brand of cheap carbon/zinc AAA cell. It never happens with Duracell alkalines. I wonder if there's a voltage sag when the cheap cell comes under load and that sets off the problem. That may explain why you're getting failures in the field and not in your test setup, if the customers aren't using the same batteries as you are. Maybe you need to test with different kinds of batteries. Although, on the other thread, someone said he reproduced it with a bench supply.

peter, do you anticipate any other changes?

will changing the chip introduce any other benifits or drawbacks?
efficiency? production cost? voltage range?

i'm a very curious individual /ubbthreads/images/graemlins/crazy.gif

Peter I just ordered a AAA premium this morning and it shipped out today.Is there a chance that I may have some of these problems or will this be one of the newer tested versions?
I am very excited about my newly arriving AAA and have had no problems with any of my other Arc lights.

Bigger head? Big enough for an a 8mm or possibly a luxeon!?
Mmmmm! /ubbthreads/images/graemlins/popcorn.gif

Peter, thanks for letting us in on your testing and troubleshooting. Along the lines of what bhds asked, will you be making any other changes to the AA/AAA? There's been a lot of talk about 8mm LEDs, 5mm ISP LEDs that are brighter than the Nicias, etc. and I too was wondering if you had any other changes in mind. I'd love to see these small lights get brighter, so any info you could give us on these plans would be greatly appreciated. Thanks again for keeping us in the loop!

P.S. My AAA had the not-turning-on-the-first-time-but-turns-on-the-next-try problem on Duracells, but I popped an Energizer in there and haven't seen the problem but once or twice...go figure. YMMV.

(sigh) At this point, I am looking only for ways to make the product more reliable. Brighter, different LEDs, etc matter absolutely nothing to me at this point.

I confirmed this morning that each unit we have been sending out has been turned on and off 50 times by hand and did so without failure. Even so, some of those same units arrived in the customers hands and did not work.

Our first priority for today is to find a test that can make the units fail consistently enough for us to use trial and error methods to find the cause.

Until then, we are no longer shipping any AAA or AA models.

Peter

Mine had the problem with the stock Duracell for the first time last week, happened again last night. It seems to only happen at night when all the lights are out. /ubbthreads/images/graemlins/ooo.gif

I cleaned the connection (thinking that might help) switched out the battery to a fresh energizer, and still got nothing. I put the old Duracell back in, and it went on as if nothing was wrong. I tried three more times, and it went on as expected. At least in my case, it doesn't look like the battery is the culprit. Hope you can nail this one quickly Peter. Good luck.
-J

[ QUOTE ]
Gransee said:
... I was talking to Henry about this last night and we both agree that we will probably have to use a different chip in the AAA. ...

[/ QUOTE ]

Though it could bring some extra work and efforts to you, I am very excited to hear your intention of changing the chip.

Time has gone with max 45mA limitation by the chip, but many regulator IC now offers more than 100mA to led with 1.5V battery without requiring many more components. Most of them need no schottky diode, but 2 registers for Vout adjustment.

Door is opening for 8mm or underdriven Luxeon.

I have a few suggestions.

1) If you maintain the same board design (physical) for AAA and AA, it has to be meant for AAA size as now. You may find some sot23/6 chips which fits well, or even umax/8 or msop/10 will fit in though you need finer threads.

2) some chips I looked at, listed only what I feel suitable for AAA board. (startup below 1V, min operating as low as possible)

I admit that I looked for the chips which could deliver over 100mA for 8mm, this led needs more than 3.6V to get enough current. But if we are talking about driving 5mm at 40+mA, fixed output of 3.3V produced good result and you can save the registers for FB.

- Linear LTC3400/3400B
sot23/6, Vout=2.5-5.0V
3.3V 100mA with single AA

- Linear LTC3429
sot23/6, Vout=2.5-4.3/5.0V
100mA from single AA

- Maxim Max1795/1796/1797
umax/8, Vout=2.0-5.5V
max Iout=75/100/200mA (Vout=5V & Vbatt=1.5V)

- TI TPS61000/61006
msop/10, Vout=1.5-3.3V
Iout=100mA from 0.8V supply

- TI TPS61010/61016
msop/10, Vout=1.5-3.3V
Iout=200mA from 0.9V supply

- TI TPS61020/61025
qfn/10, Vout=1.8-5.5V
Iout=200mA from single AA

-- DJP

Peter, are the units you're getting back that failed for customers failing at all for you?

I had given my friend an AAA as a gift. His had this problem as well and he was using a duracell. The battery felt "funny" for lack of a better term... when I compared it to a new one the size looked identical. However whenever I pushed down on the positive side, it felt as if the battery may have caved in a little. The problem was solved as soon as I put in a new battery.

peter, some poeple have reported that the problem is more evident using the cheapo or zinc batteries...maybe testing with those in would help?

maybe even make some sort of device where you screw the aaa head into it, and a computer or regulator flashes power to the led /ubbthreads/images/graemlins/icon3.gif

Peter I just got my AAA Premium in and it shows no problems so far.It is everything I expected to be and more.I now see why this item is so well liked here.
Your shipping is incredible as I have the light in my hands just over 28 hrs from the order date...very fast shipping.
Also no problems with my AA either.I guess I got one of the good ones and hope to purchase more from you shortly.
The AAA is now my favorite light for EDC and is working perfectly...thanks for keeping us informed.

Hi Peter
Just to let you know that the Arc AAA i had replaced all the way to the U.K, Works Great Its got the new <font color="green">ARC</font> inscription around the top, it has never let me down /ubbthreads/images/graemlins/grin.gif
i Hope the is of some help
And Thanks For the great service /ubbthreads/images/graemlins/bowdown.gif

Mic

Peter,

I received an email this afternoon letting me know that my AAA was shipped today. Is it safe to assume, that the glitch has been corrected.

Thanks in advance,

J Scott

Just got a delivery confirmation today that my ARC AAA Premium and AAA standard are on their way. Looks like I got my order in just in time. I'll post if either have any problems. The ARC AAA I received several months ago has performed flawlessly.

-Keith

My Arc AA will hang on occasion with a new Energizer Lithium AA battery. Tried it with a Duracell and Rayovac... same thing. It happens about 10% of the time so it is not a major thing. Maybe I'll send it in when the 8mm LED version of the Arc AA is available. /ubbthreads/images/graemlins/wink.gif Most likely, I will send it in after I buy an Arc AAA. You would not expect me to go without my keychain light...would you?

My brand new Arc AAA was a little balky at first and then it failed to turn on. I took off and remounted the head and it has since worked without fail on the Duracell. I just turned it on and off 101 times and it worked fine.

Josey

Like many real-world problems, I suspect this one is an onion - having several layers. I know for a fact (and it sounds like Peter has concluded the same thing) that there is a problem with the converter. It has nothing to do with the type of cell used. (Another layer to this problem may be the battery - I haven't confirmed that) I had a defective AAA that would only operate about 90% of the time when power was applied. I used a lab supply connected directly to the head and, upon power application, sometimes the current draw was next to nil and it didn't light.

THAT ain't a battery problem.

To test heads, all one would have to do is fixture up a test bed where the heads can be screwed-in and have DC power repeatedly applied and removed, while confirming that the correct current is drawn each time DC is applied.

Are some battery brands a problem? Maybe. But it doesn't change the fact that there's a start-up problem in the head.

Also, I applaud Peter's decision to concentrate on this problem in lieu of making it brighter, using an 8mm LED, etc. This product is perfect as is - except that it doesn't always turn on. And that is the most important feature that this product needs.

[ QUOTE ]
Gransee said:
Our first priority for today is to find a test that can make the units fail consistently enough for us to use trial and error methods to find the cause.


[/ QUOTE ]

As brikbat said, I, too, believe that it is a converter problem, failure to start oscillating. Considering this, it has no hard meaning to keep twisting the head to test. You may attach a FET or relay controlled power supply to the converter board and log the result from thousands of test with varying switch on timing or pattern, then have statistics with each components change.

From my observation, I could make some guesses.

I see that this problem occurs with the recently manufactured units only. Could it be linked to the ceramic capacitor in place of tantalum capacitor in use previously rather than the regulator IC?

Also from my experience and other posts, the problem seems occurring mosltly when turned on at first time (after long off time), subsequent unscrewing and screwing turns on regularly. Could it be helped by a minute residual charge in the capacitor to help second time?

The regulator chip seems taking operating power supply from the regulated (boosted) output. If the Vdd or PS doesn't rise up fast enough, the regulator chip may see the shdn low and go into the shutdown mode (no light). Could it be possible, then perhaps try with smaller capacitor?

I wish you all the good wisdom to solve the problem, Peter.

-- DJP