# Dim A2 Incan Mode?



## tsl (Nov 17, 2006)

I was playing around with my A2 tonight---I just can't keep my hands off of that light it seems---and I noticed that when I pressed the tailcap for the incan mode that the incan sometimes came on bright at full power while other times it came on dim. I also tried twisting the tailcap for constant on usage and got similar results.

Is that an indication that the batteries are getting too weak for powering the incan mode? I hadn't changed batteries since I got the light about a month ago.

I did pop in a pair of new Streamlight batteries, and I only saw the same thing if I slowly twisted the tailcap until it was just at that in-between stage between LEDs and incan. The incan came on dim and I heard a pretty loud buzzing noise when I held the light up to my ear---as if the regulator was working hard to provide power. Once I twisted the tailcap a little further, the incan was at full power.

I then popped the original SF batteries back into the A2, and the incan now only occasionally comes on at full power. Mostly the incan is dim.

Anyway, there are folks here MUCH more knowledgeable about the A2 than I am, so I'm just checking that this is normal behavior and a sign of weak batteries. BTW, I did clean the threads again and tried another tailcap, and I had similar results.


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## benchmade_boy (Nov 18, 2006)

yes you need to replace your batts i almost pooped my pant the first time mine did that and it was the first day i got it so i was freaking out. then after i relized it was the batts i was like did i really play with it that much i was like you i held it all day and kep turning it on.


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## oregonshooter (Nov 18, 2006)

Could also be a broken contact arm in the tailcap. I just discovered mine has this issue a few days ago.  Gonna call SF for a replacement one of these days.


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## nzgunnie (Nov 18, 2006)

mine had the dimming problem, went away with new batts.


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## Grox (Nov 18, 2006)

It's not really a "problem" per se, just a sign that the batteries need replacing. Consider it a low battery indicator.

The intermediate/low mode is normal behaviour for the A2. 

Enjoy!


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## js (Nov 18, 2006)

tsl,

Most often it just means that you cells are getting low. The regulator in the A2 will turn on if the voltage it sees is above a certain value. If the resistor in the tailcap is in series, then the regulator definitely WON'T turn on, as there is too much of a voltage drop across the resistor in the tail cap. That's the way the two stage switching is acheived through a single power path.

Anyway, once the LVR actually turns on, there is another, lower voltage value at which it will decide that there isn't enough juice left in the batteries to power the lamp and that it should turn off. So, what can happen with batteries that are right on the edge is that the LVR will turn on, but then a very short time later it will say "Ooops. Voltage too low. I'm turning off". Then it turns off, but a very short time after THAT, the voltage of the batteries bounces back up, and it says "Hey, I can turn on!" and does, and so on, and on, many times a second. The result is an "incan dim mode".

OR, if there is some extra resistance or poor contact in the circuit due to crud or (more often) a broken spring contact, then the same thing will happen.

So first check to make sure there are no broken spring contacts in your tailcap. Next make sure that the very butt of the light, and the tops of those spring contacts are both clean. NOTE that there is NO CONDUCTION through the threads, so if they aren't shiny clean, it doesn't matter at all.

Next, drop in the brand new cells and check to make sure that whenever you press FIRMLY on the LOTC that you DO NOT have the incan dim mode. If you press lightly, you can sometimes make it happen, due to the extra resistance of a not-so-great contact pressure, but if you press firmly you should not be even able to have it happen with fresh batteries. In fact, I just tried half a dozen times to make it happen (fresh cells in A2) but I couldn't get the dim incan mode at all, even with just enough pressure to start the incan and no more

Unless of course your "fresh" cells really aren't fresh. We've seen a rash of that going on with off-brand 123's. I just had about 30 Titanium 123's--brand new from the box--ALL fail to power my A2 in high mode. Stick with SF or Duracell for highest quality and reliability and consistency.

Anyway, if you go to the sticky thread post, you can find a link to my A2 review for further reading should it interest you.


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## Illum (Nov 18, 2006)

sometimes Surefire cells has issues also, not just the off brand ones

its still incredible IMO that the regulator can still keep the xenon on...


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## jrmcferren (Nov 18, 2006)

> Anyway, once the LVR actually turns on, there is another, lower voltage value at which it will decide that there isn't enough juice left in the batteries to power the lamp and that it should turn off. So, what can happen with batteries that are right on the edge is that the LVR will turn on, but then a very short time later it will say "Ooops. Voltage too low. I'm turning off". Then it turns off, but a very short time after THAT, the voltage of the batteries bounces back up, and it says "Hey, I can turn on!" and does, and so on, and on, many times a second. The result is an "incan dim mode".


Hmm Sounds like a case of "accidental" pulse width modulation, maybe surefire can add that as a feature for regular operation since the incan is regulated in the first place.

BTW, I'm not a surefire guy as I'm a college student my Mini Mag is more than enough for me.


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## js (Nov 18, 2006)

jrmcferren said:


> Hmm Sounds like a case of "accidental" pulse width modulation, maybe surefire can add that as a feature for regular operation since the incan is regulated in the first place.
> 
> BTW, I'm not a surefire guy as I'm a college student my Mini Mag is more than enough for me.



The LVR already IS a PWM regulator. So, I'm not sure what you mean by "maybe SF can add that as a feature . . ."

If you mean that they can add the dim incan mode as a feature--NO WAY. It's not very useful, and would mean a three stage tail cap. Way to complicated and sensitive to make easily reliable.

Plus, when it is in this alternating state between deciding to be on, and deciding to be off, it's not really doing a good job of PWM! It's definitely not regulated to any specific power or anything when it is doing this. It is definitely NOT a feature in my opinion. Unless only as a nice indicator of when you need to change the batteries.


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## tsl (Nov 18, 2006)

Hi Jim,

I've read your A2 opus at least once all the way through and your first post in that thread more than once. I consider you one of the most knowledgeable folks here about the A2, so thanks for the reply. Actually, thanks for the replies everyone. I didn't remember reading about the dimming behavior (just went back to JS' thread, and it's there so I overlooked it!!), so I just wanted to double-check my hunch that it was just the batteries and that everything was normal.

Can I say again just how much I love that light??!! It's a great length for my hand, and I love the incan for color rendition outdoors. Milky modded the light with THC3 LEDs, so I've got a very nice, floody low beam as well for both outdoors and indoors.


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## joema (Nov 19, 2006)

I strongly recommend two items:

(1) A ZTS pulse-load battery tester: http://www.lighthound.com/sales/zts_battery_testers.htm

(2) High quality contact cleaner, such as the Power Pen: http://www.peakledsolutions.com/acc_msc.html or the various Caig products: http://store.caig.com/s.nl/sc.2/category.188/.f Unfortunately Radioshack no longer carries the Caig contact cleaner pens, but they're available various other places.


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## Grox (Nov 21, 2006)

I would echo Jim's advice. Stick to name brand American-made brand cells for the A2 at least. In the A2, I have had success with Surefire, Duracell, Energizer and Rayovac, but titanium and batterystation have let me down. The same titanium and batterystation cells work fine in the U2 and E2 etc for some reason.


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## mat_the_cat (Nov 28, 2011)

First of all, sorry for reviving a 5 year old thread - I'm not really sure whether it's correct protocol to start a new one on (hopefully) the same subject, or just add a quick A2/CR123 newbie question here...

Anyway, I received an A2 today which came with some Surefire cells (dated 2018 so within their time expiry date). When I turned it on I wasn't expecting a ball of fire, but the incandescent mode was about the same guesstimated brightness as a Mag 2AA incan. I bypassed the tailcap to see if that was a source of extra resistance, and it was no better. Tailcap current was about 0.7A.

After Googling about the relationship between CR123 voltage and remaining capacity, I found out that you can't really tell how much is left from the voltage, but I measured it anyway and found 2.7V per cell with no load applied. So now I'm puzzled - it would suggest the cells are dead but I would have expected if they were that low, they would ONLY light the LEDs.

Easiest thing to do is obviously to buy some more cells, but I've not found anywhere within 40 miles selling them around here, so it will be Wednesday earliest by the time any arrive mail order. So I was just wondering if someone could confirm that a) the A2 should be brighter and whiter than a 2AA Maglite, and b) that a voltage of 5.4V may still be enough to light the incan bulb, albeit dimly?

I've never spent this much on a torch before, and it would set my mind at rest while I wait for more cells to arrive...thanks!


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## Bullzeyebill (Nov 28, 2011)

At 2.7 volts, no load, a CR123 is essentially dead. You might consider RCR123's, rechargeable CR123 cells, if you will be using your A2 regularly. Several threads have spoken to the use of them in the A2, and the consensus is that it is ok, though the extra voltage is a little hard on the three LED's, but there has not been much feed back about that being a real issue. I used CR123's with my A2, and there was no difference in output, measuring bounce with a lightmeter. For my purposes I had removed the LED ring.

Bill


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## mat_the_cat (Nov 28, 2011)

Thanks Bill, I had hoped that was the case. Never used them before so it's all new to me!

I have one of calipsoli's LED rings on order, which regulate the higher voltage from the RCR123s so as I plan to use it frequently (assuming I like it once up to full brightness!) they will probably be the best bet.


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## angelofwar (Feb 29, 2012)

Mine was dimming also, so I checked this out...but, thoguh I would mention, I believe this is inherent to the design. It's meant to be dim the last few minutes of incan runtime. Why do I say this??? After reading through the lengthy jargon found in the older SF catalogs, I came across some interesting reading about a whole line-up of regulated incans (that never saw the light of day unfortunatley). namely, the MD2, IIRC. They had a whole line up that would run at 60 minutes full blast, and then 15-25 minutes at a lower 25 lumen setting. Thye never advertised thsi for the A2, but, after reading about these, I think it's hnestly inherent to the design.


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