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nuckolls.bob(at)aeroelect
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 Posted: Tue Mar 14, 2017 6:30 pm Post subject: About those 'Copper Tops' |
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While sitting at the keyboard on more interesting
things, I often have some sample battery running
on cap tests. I've been gathering data to repeat
the experiment I did about ten years ago that
asked "How bad can a flashlight battery be?"
Just finished sucking the precious bodily fluids
out of some Duracell AAs marked with a 2018 Use-By
date. If memory serves, the advertising hype for
this product boasts a 10-year shelf life.
At least this batch of cells are only coughing up
about 1/2 the capacity of a new cell . . . they
demonstrate a higher internal impedance at the
beginning of the discharge cycle.
Does anyone have some Alkaline AAs out there
that are pushing their use-by dates? It would
be interesting to squeeze 'em and see how long
they'll sing.
Bob . . .
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alec(at)alecmyers.com
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| Posted: Tue Mar 14, 2017 8:14 pm Post subject: About those 'Copper Tops' |
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Apropos of this, I have a maybe-novel idea about how to test a bunch of competing battery brands, easily. I don't know if I made this up, or read about it somewhere but...
Connect them in series, and discharge the battery of cells through a dummy load. That way, at any given time, they've all passed the same number of electrons/coulombs of charge. Periodically disconnect the load and measure each cell's no-load terminal voltage. The cells that die first should be obvious.
What do esteemed list readers think?
On Mar 14, 2017, at 22:26, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com> wrote:
While sitting at the keyboard on more interesting
things, I often have some sample battery running
on cap tests. I've been gathering data to repeat
the experiment I did about ten years ago that
asked "How bad can a flashlight battery be?"
Just finished sucking the precious bodily fluids
out of some Duracell AAs marked with a 2018 Use-By
date. If memory serves, the advertising hype for
this product boasts a 10-year shelf life.
At least this batch of cells are only coughing up
about 1/2 the capacity of a new cell . . . they
demonstrate a higher internal impedance at the
beginning of the discharge cycle.
Does anyone have some Alkaline AAs out there
that are pushing their use-by dates? It would
be interesting to squeeze 'em and see how long
they'll sing.
Bob . . .
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nuckolls.bob(at)aeroelect
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| Posted: Wed Mar 15, 2017 10:48 am Post subject: About those 'Copper Tops' |
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At 11:10 PM 3/14/2017, you wrote:
| Quote: | --> AeroElectric-List message posted by: Alec Myers <alec(at)alecmyers.com>
Apropos of this, I have a maybe-novel idea about how to test a bunch of competing battery brands, easily. I don't know if I made this up, or read about it somewhere but...
Connect them in series, and discharge the battery of cells through a dummy load. That way, at any given time, they've all passed the same number of electrons/coulombs of charge. Periodically disconnect the load and measure each cell's no-load terminal voltage. The cells that die first should be obvious. |
This is a useful comparative test for evaluating
the relative condition of an array of cells . . .
with limitations. It doesn't yield 'baseline' data,
i.e. a quantitative measurement of contained
energy. When I did the first pass at this study
I had a nifty $100, 12-Bit DAS purchased
previously for a Beech flight test program.
Pairing this device with an array of AA cell
holders loaded with 5 ohm resistors allowed me
to run batches of cells down at the same time.
The data yielded was analyzed in software I can't
run under Win7 . . . software that coughed up a
scrip file that plotted results to a graph in
AutoCAD.
[img]cid:.0[/img]
The Phase II test is being accomplished one cell
at a time using a West Mountain Radio battery
tester and its companion software. The earlier
tests were conducted under a constant resistance
load; Phase II is constant current. In both instances,
the analysis yielded a Watt-Hours value for energy
yielded by each cell.
The disadvantage is lack of batch-processing
capability. The advantage is that software supplied
by WMR runs in my more modern computers and also
yields quantitative data.
Still got a soft spot in my heart for that $low$
DAS. It ran under Win95 off the parallel port
of the laptop. It would gather 1000 samples per
second of 12-bit data. In about two weeks of
hammer-n-sawing at the bench, I had fabricated
and installed a pitch-trim study on the Beechjet
that yielded some really nice data . . . along
with foundation for fixing a problem that was
costing the company $millions$.
Those were exciting times . . .
Bob . . .
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