Re: Alkaline Battery Shelf Life and contrived, totally fictional, extreme examples [was: Re: Canon A710 IS discontinued??]

On Mon, 30 Jul 2007 09:41:53 -0700, Tom Delaney wrote:

I went back on Google Groups and read that post, it's at
http://groups.google.com/group/rec.photo.digital/msg/8543dec625086905 for
those that want to see it.


Your example made no sense at all. It was no explanation at all. Not a
surprise with a "contrived, totally fictional, extreme example." Simply put,
it was wrong. Examples, while never proof, are often useful when they are
non-contrived, non-fictional, and non-extreme.

Then you have a comprehension problem. While the example doesn't
cover every possibility, it provides a more than plausible
explanation for why a battery's shelf life may appear to be reduced
if it had been previously used. For those that don't care to start
up their browser but might want to judge your wisdom or lack
thereof, here's what the text at the link contained :

On Tue, 17 Jul 2007 02:50:09 -0500, Ron Hunter wrote:
Something to consider when using alkaline batteries is that even though
the shelf-life is quite long if the batteries have not been used at all,
they deteriorate much more rapidly after the first use, even if it is
minimal. They should still be good for a couple of years, though, which
should be fine for all but the VERY occasional user.
I have not seen figures for how much, if any, similar effect there is
for lithium disposables.

Where did this theory come from? I haven't seen *any* indication
that the shelf life declines by more than what one would expect from
a given amount of pre-use. I'm not surprised that you haven't seen
figures for this effect in lithium batteries. I'd also be surprised
if any battery manufacturer has published any figures for this
effect in alkaline batteries. :)

Part of the what you're talking about may depend on how you define
the length of "shelf life". I'll explain with a contrived, totally
fictional, extreme example. Suppose the shelf life of a 2,400mAh AA
alkaline battery is defined to be the point that where if it has
never been used, it has lost 50% of its capacity so that only
1,200mAh remains. Sitting on a shelf it would take 8 years to reach
this point. Now take a fresh 2,400mAh battery and use it over a
couple of days until it has only 1,200mAh of its capacity remaining.
If one can assume the same rate of decline due to self discharge,
one might expect that it would take 8 years of sitting on a shelf
for the remaining 1,200mAh to decline to 600mAh, representing the
same 50% loss after 8 years. But if you assume that the true
definition of shelf life for this battery is the point that its
capacity has declined to 50% of its original capacity, the pre-used
battery would have reached the end of its shelf life after it was
used for those "couple of days", even though it still contains an
appreciable amount of energy, much of which will still be available
for use 8 years later.

Energizer's numbers are actually much more conservative than the
"fictional" ones I provided, using for its definition of shelf life,
not the loss of 50% capacity after 8 years, but the loss of only 20%
of capacity after 7 years. That's part of the reason for including
the "contrived, totally fictional, extreme example" disclaimer. I
wanted to provide (as I said) a plausible example. The explanation
is still valid, whether 50%/8years or 20%/7years is used, but it
saved me the time of looking up unnecessary data, and also allowed
the use numbers that might make it a bit easier to for others to
follow the math. If you still don't understand this, and continue
to think that the example makes no sense at all, then you're quite
the dense individual.


Once the chemical reaction inside the battery begins, the shelf life of the
remaining capacity is significantly reduced. Occasionally you'll see
alkaline shelf life properly qualified with "Shelf Life of Unused
Batteries."

As I previously said, the shelf life does not become greatly
shortened after alkaline batteries are first used, although it may
slightly accelerate the process. This is going by the fact that
several devices that had been put aside for many years continued to
operate for many hours when later discovered, and the batteries by
that point had passed their expiration dates by several years. If
you spent 1/10th the effort to examine SMS's numerous distortions
and bogus pronouncements, you'd find him to be completely dishonest.
But I now have to conclude that you're also, in your own way less
than truthful as you, too, have ignored the questions that I posed
asking to look into SMS's bogus battery statements, and are
seemingly only trying to peer under rocks looking not for the truth,
but for any scraps that might support you predetermined conclusions.


Shelf life of alkaline batteries, as in shelf life of food, is based on the
product being unused. Once the chemical reaction inside the alkaline battery
has been started, the shelf life printed on the package no longer applies.
This is common knowledge (or so the manufacturers believe), so there is no
need to print "Good Until 2013 Unless Used Before Then." On some Duracell
battery packages they print "Guranteed Fresh Until 20xx". On some Energizer
packages they print "Use By 20xx." On some packages, they just print a date
with no qualifier. Probably the "Guaranteed Fresh Until 20xx" is the most
descriptive, as obviously a used battery would not be "Guaranteed Fresh."
When you open a can of food with a "Good Until" or "Use By" date stamped on
it, it's clear that you have to use the food once it's opened, you can't
keep it around, even refrigerated, for a couple of years until the stamped
date.

It's not common knowledge at all. You just pulled that tidbit out
of thin air. I now see that you have something in common with SMS,
who also makes many similar self-supportive but unverifiable
statements. Your analogy will remain ludicrous until batteries
start using organic materials subject to spoilage. If it is
applicable to any battery type it would only be Zinc Air batteries,
after the seal is removed.


Once the chemical reaction inside the battery begins, the shelf life of the
remaining capacity is significantly reduced. Occasionally you'll see
alkaline shelf life properly qualified with "Shelf Life of Unused
Batteries."

Don't be another SMS. How much is the shelf life reduced? I'm
willing to accept that it might be by a slight amount, but unless
you can provide a mechanism, "significantly reduced" seems doubtful.
Who said it, and where is the data available? It doesn't match what
I've found from personal experience.


In an MIT lecture on batteries, at
http://web.mit.edu/2.72/www/lectures/Batteries.pdf, page3, the author
was specific about shelf life of alkaline-manganese batteries stating: "The
shelf life of the cell (in unused condition) is at least 3 years."

The author was not specific at all. For readers that didn't look
at the PDF file, it's not at all intended to provide a thorough
examination of batteries. It's provides only a very brief overview
of batteries to apparently support one small part of an
undergraduate course titled "Elements of Mechanical Design" where
students attend lectures that introduce "basic machine elements".
This particular PDF file was sloppily put together and contains
errors that are surprising in anything used at MIT. Some may almost
be excused if they were based on outdated information. Some
examples are :

On lithium batteries:
These batteries have a shelf life in excess of 10 years
Not really incorrect, but I've previously given about 15 years
based on printed expiration dates. Energizer's data sheets back
this up, also stating 15 years.

the capacity of the AA size is approximately 1.6 Ah.
Wrong. Energizer's L91 lithium AA batteries are rated at 3000mAh
in Energizer's Engineering Data***. Even alkaline AA batteries
are rated at up to 2,900 mAh for small currents and slightly less
than 2,000mAh for 500ma loads.

(Self Discharge: 5% loss in first 24hrs, 5-10%/month afterwards)
I can't tell if this is a mistake or not, but it stood out as a
bizarre statement, coming as it did in this section on "Primary
(Disposable) Batteries" in the "Lithium batteries" subsection. For
what it's worth, it immediately followed the description of CFX type
lithium coin cells, and I'm not familiar with those.


In the Battery Lifecycle Cost table
Battery Cost $1.00
For primary AA cells, alkalines assumed but not stated. Not too
far off, although I pay about $0.20 per AA

Cost per battery $70
Way off. This is stated as the cost of a rechargeable NiMH AA
cell. Further down there's an indication that this may be the cost
of a multi-cell battery pack. If so, it's a sloppy apples/oranges
comparison. Data in this table (figure 2) was also given for NiCd
batteries. In another table (figure 3), a battery pack was included
that didn't state what type of cells were used. Based on the cost
($50) it could have been NiCd or Lead Acid. But based on capacity
(1000mAh) and considering the date that the table was originally
produced, this wouldn't have been for NiCd batteries, but would have
been accurate for the NiMH cells of the time. Again, sloppy.

Internal resistance 200 to 300 (mW)
What? This is for NiMH cells. Milli-Ohms yes, mill-Watts, no.
And the table inexplicably says that it includes the resistance of
peripheral circuits, so it doesn't really represent the internal
resistance at all! Energizer rates their NiMH AA cells as having an
internal resistance of 30 milliohms, not even close to 200 - 300
something or other.

On Alkaline-manganese batteries:
The shelf life of the cell (in unused condition) is at least 3 years
Sure thing. But based on expiration dates, alkaline batteries
have shelf lives of 7 to 8 years. What kind of alkaline batteries
are these? Perhaps they weren't what *we* refer to as alkalines.
Based on Energizers Datasheets, there are three types of alkalines,
all of them based on a Zinc-Manganese Dioxide Chemical System. But
two of them, the E91 and X91 (E²) AA cells have capacities of nearly
3,000mAh, and the other, Energizer's 1215, is identified as their
"SUPER HEAVY DUTY" AA cell and is only rated at 1,100mAh.

Maybe the graduate student(?) that put together this PDF slide
show was referring to these low end batteries? Unlike the other
two, Energizer doesn't use the word "Alkaline" to describe their
1215 Zinc-Manganese Dioxide AA cells anywhere in the Data***.

Are you really who you claim to be? In your zeal to defend SMS
and attack me, you appear more like a hired gun or friend of SMS.
In fact, since your name hasn't appeared in this newsgroup for more
than the last couple of days, you seem eerily reminiscent of the
many attack-sock puppets that have been plaguing this newsgroup in
recent weeks. In fact, I think that the first message you posted
here called my Sock Puppet Troll List "stupid", and asked me to
ignore and leave the sock puppets alone. And both you and SMS have
a fondness for searching Google Groups to get your ammunition. So
if you really have no relationship with SMS, that will only be borne
out over time based on the body of your messages. Your credibility
might also get a boost if you're able to find the flaws in many of
SMS's bogus statements. If you make no attempt to do this, your
identity will remain highly suspect.

.

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