Battery Capacities

Paul M wrote:

There is probably at least one a standard test protocol already. There
may be an industry standard, and it seems likely that large buyers --
especially military -- have performance standards and acceptance testing
procedures. Many different types come in the same packages, and slight
changes in chemistry can suit a cell either to bursts of high current or
to long slow discharges, but not both. A general testing spec can become
complex.

Writing to the makers of some heavily advertised cells asking for
technical information to back up their claims, and for how you could
verify them yourself, might bring you the information you want.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Paul M <PaulMatWiredogdotcom> writes:


http://www.duracell.com/oem/


Is that any use?  That's my usual reference for run of the mill
batteries.

Chris
--
Chris Eilbeck

On Sat, 30 Dec 2006 18:51:34 +0000, Chris Eilbeck


I have a flashlight fetish. I do, or did, a lot of work on stuff not
very well lit and carried a pocket flashlight with me. I also make
maps of caves, so used headlight a lot. When bright white LEDs were
first manufactured, I converted the best headlight gear I could find
to LED. This was an instant hit with other cavers and I found myself
beset with requests for similar conversions so I started a little
business that my daughter could work at making conversion kits for
different lights. This all just reinforced my fetish. Nowadays I wear
a 1 watt LED light that uses three AAA batteries. These get sucked dry
after a day or two, depending on how well I remember to cut the light
off after done. This means I am spending 30 to 40 bucks a month on
batteries just for the headlight. I was looking to see how much of a
capacity increase AAs have over AAA. I was thinking of building a new
headlight using AA batteries or perhaps a single C. If I go with a non
electronic design I must use three cells to get the voltage high
enough and then limit the current by using a dropping resistor in
series with the LED. This is how the light I use now works.

I change batteries at around 1.2 volts, so using the graphs from the
duracell site this is reached at just under one hour with a .25 watt
load for the AAA and just over four hours for the AA. This indicates
that I will be getting 4 to 5 times the life from AA. This is a lot.

 I purchased a hand light that has what must be a tiny switching
supply because 1.5 volts will not run a LED. The circuit is current
regulating (if these people used a similar design to the one I made)
so it should be able to use much more of the available power in the
battery you waste because it dropped to an unusable level. Of course
you have the efficiency losses.

And now we have the newer chemistry batteries. I've even seen some
prototype fuel cell batteries being toyed with the size of AA. Life is
more complicated.

The Lithium batteries cost 2 to 3 bucks a battery for AA but they sure
do last in a camera. They say seven times longer. Even at three bucks,
this means it is a better value than regular Alkaline batteries at 50
cents each.

Paul M <PaulMatWiredogdotcom> wrote:


You could consider the rechargable ones.

AAA at 1000mAh
 AA at 2700mAh
  C at 2600mAh
  D at 2600mAh

The reason that the AA version seem to have such a good figure is because
more effort went into improving that range as it is a very popular size of
cell.

My head LED torch uses three AA rechargeable cells and seems to last 4 hours
on the high setting and up to 16 hours on the lowest setting. Very useful
when on very dark hill-sides. My camera and portable CD player uses the
same cells.

--
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Paul E. Bennett wrote:

   ...


   ...

I've been told that rechargeables should be used only in devices like
cameras and cell phones that shut down when the voltage drops too low.
Completely discharging them is said to greatly shorten their lives. Of
course, a regulator can do that. There probably are available chips.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Jerry Avins wrote:


You are correct about that fact Jerry. My headtorch, CD player, Camera and
other devices do auto-shutdown when the battery voltage gets too low. these
little gadgets get more clever every day ;>

--
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Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/>
Mob: +44 (0)7811-639972
Tel: +44 (0)1235-811095
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
********************************************************************

Paul E. Bennett wrote:

I'd be concerned that a light I depend on would shut down with little or
no warning. That's not always a good exchange for greater life. I think
of such systems as "brittle", by analogy with structures. For example, I
would be more comfortable with a chain that deformed at 5 tons and broke
at 8 than I would be with one that deformed at 9.5 and broke at 10.

By the way: in the early days of NiCds, C and D cells had the same
rating because the Ds were actually Cs in D-cell wrappers. Could the
same be true of NiMHs now?

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Jerry Avins wrote:


The head torch has several brightness levels and it does have a battery
state indicator which can be inspected at intervals to see how you are
doing. If you were using the brighter settings when it went out then
selecting the lower brightness settings would get you light for enough time
to find the spare battery set (I always carry spare).

[X%]
 

That may be so but I wonder if anyone in the battery industry might hop up
to confirm that.

--
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Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/>
Mob: +44 (0)7811-639972
Tel: +44 (0)1235-811095
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
********************************************************************

Paul E. Bennett wrote:

At one time, I read in Consumers Union's magazine "Consumer Reports" --
see http://www.online.consumerreports.org/homepage/  -- that Radio Shack
was the only vendor of cells they had tested whose D cells were not
wrapped Cs, and that their considerably higher (about double) capacity
reflected that. I bought some. A friend who used another brand asked why
my cells were so heavy. More than that, I can't say.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

On Mon, 01 Jan 2007 15:32:50 +0000, "Paul E. Bennett"


In caving where a main light failure a mile inside the earth is a big
thing, we always carry several backups. The light I would like to
build would have a bypass to the electronics so you could continue.
LEDs have the convenient property of putting out light at lower
currents. They even get more efficient at lower currents.

Most cavers do not use rechargeable because they have less capacity
and tend to let you down in the cave. It's nice to be able to use
both, which I do sometimes.

Paul M <PaulMatWiredogdotcom> writes:


It may be different in the US but when I was caving in the UK we
tended to use miner's lamps with lead/acid batteries or the newer (at
the time) technology of Speleotechnics FX2s.  A few people used
carbide lights but always had electric backup too.

Chris
--
Chris Eilbeck

On Mon, 01 Jan 2007 18:05:37 +0000, Chris Eilbeck


A few cavers still use the miner lamp and huge lead acid battery. I
used to cave with a fellow that would use nothing else. The FX2 was
the upgrade to the miner lamp and was pretty popular here. A lot of us
used the Pezel Duo, which is the main light I made conversions for.
LEDs changed everything. Their efficiency and reliability won over
most people. Many do not like the color of the white light but the
better LEDs are nice yellow white instead of the harsh blue white.

I still use carbide sometimes for the sake of tradition. It has come
in handy on a few trips as it the carbide light acts as bad air
indicator. I carry some low wattage LED light which gives me weeks of
light in my pocket. It is amazing how little light you need see well
enough to move around, once you have been in total darkness for a
while. That does not do you much good when you can't light up the
walls or ceilings to get your bearings in one of those huge rooms you
find. Lighting up a 200 ft ceiling was the main reason cavers stayed
with the old mining lights but a 3 or 5 watt Luxen LED with a good
focusing lens will out perform the mining lights by double now and can
be powered by a head mounted battery pack.

What do you think about the rediscovery of Titan cave? I can't
remember exactly where it is, maybe the Dales?

Paul M wrote:

Don't white LEDs put out more light when pulsed with high currents at
low duty cycles? Red ones do.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

proclaimed to the world:


It is true for some rechargeable. The ma/hr rating gives it away. In
the cases I ran across, it was AAA put in AA cases. The AA had the
same rating as the AAA. You could buy a true AA if you liked, for a
greater price. The company was Powersonic and I talked with the no the
phone about it. I had both the fake AA and a real one. You could tell
the by the weight.

Paul M <PaulMatWiredogdotcom> writes:

**snip**


I'm tinkering with a design for a bike light using two 3W luxeon LEDs,
a 2S lithium polymer pack and a microprocessor-based switching
regulator.  

I've pretty much given up using alkaline cells in anything I build
because of the high vibration environment a lot of my stuff is subject
to and the necessity to use spring contacts, I much prefer a proper
soldered-contact.

Chris
--
Chris Eilbeck