Shelf life question

Dizos

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Howdy

I've been lurking around this forum for a couple of weeks. I have a C3 and a X5T on the way. Figure its time to ask a question.

Does the 10 year shelf life of 123A's remain the same if the batteries are sitting in an unused flashlight?

Thanks,

Dizos
 

nihraguk

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saaby: i've had someone relate to me that storing 123 cells in a flashlight can make them discharge themselves, whether in streamlight scorpions or surefire 6Ps. personally i've never experienced that, but that's because i don't usually keep 123 cells in my lights long enough. regular batteries can discharge faster when left in an appliance, and i think lithium cells would not be any different. someone correct me if i'm wrong, but lithiums only discharge themselves at a slower rate and don't leak as compared to regular alkalines, right?
 

Charles Bradshaw

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Welcome to CPF, Dizos!

I never heard that lithiums would discharge faster when left in an item that is turned off, and not drawing any current (until now). Don't know if it is true or not.

Shelf life usually means sitting on a shelf, not used and length of time they are good for in this condition.

NiCads and NiMHs do discharge by themselves, just sitting on a shelf.
 

Chris M.

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The only real way batteries left inside a light would self-discharge faster than if they were left outside is if the light was drawing a tiny amount of power when off. This could occur in lights with electronic switching - microprocessors and logic circuits powered directly, to be ready when the power button is pushed - lights with "always On"/locator features that glow or blink dimly so you can find it in the dark - or lights with less than ideal switches or poorly designed internal constructions that allow a degree of resistance - barely noticeable even with a decent digital ammeter, but enough to drain a cell in up to half the time it should take. Lithium or alkaline, it doesn`t matter - but the inherant shorter shelf life of alkaline cells makes their discharge more noticeable. Coupled with a lesser initial capacity of course.
Temperature has a part to play in self discharge too. Lithium cells are more forgiving of the ambient temperature than alkalines, and will not degrade so much in extremes of heat or cold. Not to say they don`t degrade at all, but the degree of capacity reduction is a lot less.

In an ideal world, a light that is turned Off would draw Zero current, but this is not an ideal world! The two you mention are good lights though and I don`t see that premature draining of cells would become a significant issue in those. You should get your 10 years easilly.

Besides, I`m confident you`ll like them so much when you get them, that you`ll not be able to put them down for long, and will burn the little red cells up in next to no time! That`s the general experience I have
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And yes - Lithium batteries don`t leak. The resultant chemicals in used alkaline cells are very corrosive and will eat right through the metal casing if there`s any flaw in its internal coating, but Lithium cells are different and in the years I`ve used them, I`ve never known one to leak ever.

They just give off quite strong, almost sweet- smelling gas....that.....is.......quite........intoxicating..........night-night gas..........

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monanza

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It all depends on what it means when an appliance or tool is 'OFF'. If there is an actual mechanical disconnect in the system (as in most flashlights) then there is virtually no leakage current and the batteries will last as long in the light as out of it (internal discharge). If there is an electronic or 'soft' disconnect (or if the mechanical disconnect is not very reliable) then the miniscule leakage current in the electronics will shorten the battery life.

Cheers.
 

nihraguk

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chris: the person who related that to me was a reservist explosives ordinance guy. most of his squad-mates experienced the same problem, whether with scorpions, surefires, or any other lithium power light. basically they put in new batteries, and after a few months the batteries may have discharged to maybe 70% of their runtime. i don't notice it if it really does happen, because as you've guessed i use up the batteries pretty quickly
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and yes...although some say the lithium batteries stink, i find the smell pleasant
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perhaps the problem has got something to do with the batteries giving the metal body of the flashlight a static charge, which gets dicharged when the light touches or rubs against something. repeated touching or rubbing the light may eventually cause the cells to discharge noticeably. this is just a theory though, since i'm not sure how good a conductor the anodizing on a flashlight is of electricity
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maybe flashlights with a CE rating, safe for use in explosive environments would not experience this problem, since they are completely insulated.
 

Dizos

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Thanks for the info. I would like to put one of the new inexpensive G2's in my trunk and "forget about it" but was a bit worried about a slow drain.

-- Dizos
 

monanza

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Very interesting nihraguk. I did not think of the environmental conditions which may compromise the integrity of the electrical path. I wonder if hermetically sealed lights would experience the same discharge problem. This is assuming that the lights are not being accidentally activated in storage.

I don't know if static discharge can account for the leakage because the battery will quickly develop a reverse potential from the loss of charge balance, which would prevent further discharge. Or am I way off here?

A battery will discharge 30% of its capacity in six months if the leakage current is 100 micro amps or so (equivalent to discharge across a 30K resistor). IIRC electrical switches (dielectric ratings) are typically rated at tens or hundreds of Meg-Ohms. The leakage current on these is several orders of magnitude less than that required to discharge the batteries at the rates we are talking about.

Anyone experience this in other environments? Anyone care to offer another explanation or hypthesis?

Cheers.
 

brightnorm

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Originally posted by monanza:
....Anyone care to offer another explanation or hypthesis?

Cheers.
<font size="2" face="Verdana, Arial">I wonder if battery quality plays any part in this, or are Surefires and Sanyos or other "lesser" brands equal in self-discharge vulnerability?

Brightnorm
 

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