Gas build up in Arc AAA?

Greetings,

Recently I whipped out my Arc AAA from it's storage location on my keyring to put it to use. It looked like the LED may have been dimly lit (it was indoors with the lights on). I tried to turn the twistie, but it was stuck. I could not easily twist the head in or out. I really had to crank on the twisty to get it to unscrew. At a certain point there was a "POP" like a little pop-gun going off. The O ring had been pushed out and there was an odd odor in the air. I pushed the O ring back on, re-installed the head and all was well.

Last night I had a similar experience. I pulled out the Arc in the dark and the LED was definitely dimly lit. I could barely twist the head, but it was easier than the first experience. I twisted till the pressure released, then re-installed the head. The battery was pretty shot by then. I replaced the battery and all was still well.

It would appear that in my pocket the head is slightly tightening and inadvertantly turning on the LED (This was a big problem with my Gerber sonic). I also noticed that if the head is just twisted till the light turns off, that slight pressure on the head will cause the LED to light. I think I was victim to both of these problems. The lights were likely doing long continuous duty in my pocket.

The surprise was the pressure build up in the body. Normally when I forget and leave a light on the result is dead batteries. The water/air tight body of the ARC is unique and stores up any pressure inside. Anyway, just curious if anyone else has some thoughts or experience with pressure build up in flashlights.

In the mean time the ARC is getting a full twist after the LED goes out.

Thanks, TR

Hello Pizzaman,

Alkaline cells can vent when discharged to a very low level.

I recommend you replace the cell (if you haven't already) and to check for any signs of corrosion inside the Arc-AAA. Especially at the negative contact (inside the batter tube, at the very bottom).

If you find corrosion, check the Arc forum for posts about cleaning the contacts or send me an email. Thanks.

Peter

I did a long burn test 12+ hours on a ArcAAA once. Same thing happened to me. If i recall the battery drained down to an open circuit voltage of below 0.4v
At this point I think the batteries outgas and the pressure can make the head very difficult to turn.

Tips:
- I would make sure you give it a complete turn for off.
-If it turns real easy you might consider replacing the O-ring. That might prevent accidental activation.
-Change the battery ever 5hrs of use or every 6months whichever comes first. Older batteries are more likely to leak or outgas.
-Dont use Heavy Duty (carbon Zinc) batteries. They are notorious for leaking.
-If you are going to do extreme run time tests I would recommend removing the O-ring before the test.

Gransee and cave dave,

Thanks for the helpful details.

The first time around the battery seemed OK. The second time, the battery was toast and I replaced it. No signs of corrosion. I have been using Duracell alkaline batteries, but will soon change over to Energizer lithiums.

I'm sure a light with a lesser seal would have vented the gas. The ARC is sealed good. The ease of twist is a little light, but still acceptable. I should probably pick up a spare O ring or two for spares.

I'm still waiting for news of an ARC AA. My li'l AAA desperately needs a big brother.

Regards, TR

I've been running a lithuim cell in mine for the past 6 months without a hitch or pop for that matter.

chiphead (ARC Premium)

This outgassing from alks contributes to the invisable, nonconductive, film that can collect on contacts causing intermittants or no light at all. I'm tempted to switch to lithiums because even if they leak I don't think they corrode the metal. Any time you've run down an alk, toss it, even if it has some life left.

Forgot to add...any time the Arc's head won't unscrew easily, push it real hard toward the body as you twist the head, to counteract the pressure,

Exact same thing happened to me a long time ago with my CMG Infinity Ultra, something felt wrong so I unscrewed it and finally the head jumped out and it let out a loud pop like a bottle of champagne. Didn't realize why it had happened or that it could be damaging, perhaps that has to do with why it got too finicky to use a short time later. Thanks for the possible insight.