Why is it that rechargeable batteries state the capacity,eg., 2500 mAh but
the 'use once' sort don't?


mark

mark wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500 mAh but
the 'use once' sort don't?


becaue..they dont actually HAVE a capacity in tesame sense.

A rechargeable is generally rated at a 10 hour discharge rate: with
decent cells that capacity is broadly constant across anything from 10
minutes to about 100 hours. Dry cells are not like that. They rapidly
polarize under high currents, but then 'recover' if left alone.




mark

The Natural Philosopher wrote:
mark wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500 mAh
but the 'use once' sort don't?


becaue..they dont actually HAVE a capacity in tesame sense.

A rechargeable is generally rated at a 10 hour discharge rate: with
decent cells that capacity is broadly constant across anything from 10
minutes to about 100 hours. Dry cells are not like that. They rapidly
polarize under high currents, but then 'recover' if left alone.




mark

If you look in the technical data on the manufacturers sites you will
find mAh data.
ie

http://www.duracell.com/oem/Pdf/new/MX1500_US_UL.pdf

mark wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500 mAh but
the 'use once' sort don't?

I suppose its a selling point and also indirectly an indication of
quality on a rechargeable - they are probably also bought by more clued
up users.

Dry batteries also have a stated capacity - but often only on the makers
data sheets rather than boasted on the side of the battery.

Note the discharge characteristics will be different - you may not be
able to draw the full capacity from a dry cell in quite such as linear
was as you can from a rechargeable.

Some of the figures are available though:

http://cpc.farnell.com/BT03888/batte...acell-15070555



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
mark wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500 mAh
but the 'use once' sort don't?

Probably because it's not in their interest. Better to show bunnies going
on and on...

But some pro suppliers do give these details.

--
*How do they get the deer to cross at that yellow road sign?

Dave Plowman London SW
To e-mail, change noise into sound.

Why is it that rechargeable batteries state the capacity,eg., 2500 mAh
but the 'use once' sort don't?

Probably because it's not in their interest. Better to show bunnies going
on and on...

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.


NT

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.


NT
Often I would suspect because some devices cease working before the
terminal voltage used in the capacity calculations is reached.

On Dec 10, 7:08*pm, robert wrote:
The Natural Philosopher wrote:
mark wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500 mAh
but the 'use once' sort don't?

becaue..they dont actually HAVE a capacity in tesame sense.

A rechargeable is generally rated at a 10 hour discharge rate: with
decent cells that capacity is broadly constant across anything from 10
minutes to about 100 hours. Dry cells are not like that. They rapidly
polarize under high currents, but then 'recover' if left alone.

mark

If you look in the technical data on the manufacturers sites you will
find mAh data.
ie

http://www.duracell.com/oem/Pdf/new/MX1500_US_UL.pdf

It used to be given in (I think) the Rapid catalogue, maybe Maplin but
I haven't bothered with theirs for quite a few years.

MBQ

On Dec 11, 8:51*am, robert wrote:
Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.

NT

Often I would suspect because some devices cease working before the
terminal voltage used in the capacity calculations is reached.

Time to mention http://bigclive.com/joule.htm again?

MBQ

On Dec 11, 1:45*am, wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500 mAh
but the 'use once' sort don't?
Probably because it's not in their interest. Better to show bunnies going
on and on...

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.

Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it, or just an urban myth?

MBQ

Man at B&Q wrote:

Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it, or just an urban myth?

If it was false, wouldn't it best to power the factory making them, from
lots of them?

In article
,
Man at B&Q wrote:
On Dec 11, 1:45 am, wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500
mAh but the 'use once' sort don't?
Probably because it's not in their interest. Better to show bunnies
going on and on...

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.

Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it, or just an urban myth?

I'd bet it is true - and by a factor of many. Then there's the energy used
to transport it etc.

--
*Stable Relationships Are For Horses. *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article
,
Man at B&Q wrote:
On Dec 11, 1:45 am, wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500
mAh but the 'use once' sort don't?
Probably because it's not in their interest. Better to show bunnies
going on and on...

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.

Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it, or just an urban myth?

I'd bet it is true - and by a factor of many. Then there's the energy used
to transport it etc.

Of course it's true, otherwise the laws of thermodynamics would be in a
pickle and the universe would probably explode fairly quickly as entropy
would be reversed!


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

On Thu, 11 Dec 2008 01:01:10 -0800 (PST), "Man at B&Q"
wrote:

On Dec 11, 1:45*am, wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500 mAh
but the 'use once' sort don't?
Probably because it's not in their interest. Better to show bunnies going
on and on...

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.

Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it, or just an urban myth?

No. My perpetual motion machine runs off them. ;-)

--
(\__/) M.
(='.'=) Owing to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking most articles
posted from there. If you wish your postings to be seen by
everyone you will need use a different method of posting.
See http://improve-usenet.org

Man at B&Q wrote:

It used to be given in (I think) the Rapid catalogue, maybe Maplin but
I haven't bothered with theirs for quite a few years.

I still have a 1995 Maplin catalog on the shelf - kept because it was
the last one to include lots of technical information and device pinouts
etc.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

robert wrote:

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.


NT
Often I would suspect because some devices cease working before the
terminal voltage used in the capacity calculations is reached.

I have recently had a set of Energiser Lithium AA cells in a camera.
They lasted *far* longer than 'ordinary' alkalines which I usually use.
Maybe they are sufficiently good to be worth paying their hefty premium?
But I do wonder how much is simply loss of voltage rather than actual
energy content.

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

Rod wrote:
robert wrote:

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.


NT
Often I would suspect because some devices cease working before the
terminal voltage used in the capacity calculations is reached.

I have recently had a set of Energiser Lithium AA cells in a camera.
They lasted *far* longer than 'ordinary' alkalines which I usually use.
Maybe they are sufficiently good to be worth paying their hefty premium?
But I do wonder how much is simply loss of voltage rather than actual
energy content.

Quite - if the camera or device's battery life detector can't be set up
for the different discharge characteristics of the available batteries
then there is a good chance that the device will close down while there
is usable energy in the battery.

However looking at the Ultimate Lithium discharge curves - they seem
flatter than alkalines and thus shouldnt suffer from early close down.

http://data.energizer.com/PDFs/L91ULT_EU.pdf

robert wrote:
Rod wrote:
robert wrote:

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.


NT
Often I would suspect because some devices cease working before the
terminal voltage used in the capacity calculations is reached.

I have recently had a set of Energiser Lithium AA cells in a camera.
They lasted *far* longer than 'ordinary' alkalines which I usually
use. Maybe they are sufficiently good to be worth paying their hefty
premium? But I do wonder how much is simply loss of voltage rather
than actual energy content.

Quite - if the camera or device's battery life detector can't be set up
for the different discharge characteristics of the available batteries
then there is a good chance that the device will close down while there
is usable energy in the battery.

However looking at the Ultimate Lithium discharge curves - they seem
flatter than alkalines and thus shouldnt suffer from early close down.

http://data.energizer.com/PDFs/L91ULT_EU.pdf



Thanks.

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

"Man at B&Q" wrote in message
...


Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it,

Now that explains what was before the big bang.
Have you suggested it to that Hawkins fellow?

Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it, or just an urban myth?

No. My perpetual motion machine runs off them. ;-)

There was a supposed perpetual machine that did. It used 2 battery
piles disguised as just supporting pillars to electrostatically
attract a clock pendulum, and this slight force was enough to keep the
clock running.


NT

On Dec 11, 9:45*am, "Bob Mannix" wrote:
"Dave Plowman (News)" wrote in ...



In article
,
* Man at B&Q wrote:
On Dec 11, 1:45 am, wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500
mAh but the 'use once' sort don't?
Probably because it's not in their interest. Better to show bunnies
going on and on...

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.

Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it, or just an urban myth?

I'd bet it is true - and by a factor of many. Then there's the energy used
to transport it etc.

Of course it's true, otherwise the laws of thermodynamics would be in a
pickle and the universe would probably explode fairly quickly as entropy
would be reversed!

Does it take more energy to process Uranium ore than can we get from
using the resulting compound in a nuclear reactor?

Does it take more energy to pick a few lumps of coal off the floor at
an open cast mine than you get from burning it?

If so, these would also seem to put the laws of thermodynamics in a
pickle. Due to natural processes (or divine providence in the words of
the Polish guy on R4 describing his country's abundance of coal) these
substances are able to yield energy to us that was locked up millenia
ago.

It boils down to how much of the energy of a primary cell is put there
by the processing of the constituent chemicals versus the potential
energy in the raw materials. Is it all due to the processing?

MBQ

"Rod" wrote in message
...
robert wrote:

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.


NT
Often I would suspect because some devices cease working before the
terminal voltage used in the capacity calculations is reached.

I have recently had a set of Energiser Lithium AA cells in a camera. They
lasted *far* longer than 'ordinary' alkalines which I usually use. Maybe
they are sufficiently good to be worth paying their hefty premium? But I
do wonder how much is simply loss of voltage rather than actual energy
content.

You should be using NiMh rechargeable in most cameras.
The cameras have high discharge currents and alkalines can't keep it up.

On Dec 12, 9:40*am, "dennis@home"
wrote:
"Rod" wrote in message

...



robert wrote:

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.

NT
Often I would suspect because some devices cease working before the
terminal voltage used in the capacity calculations is reached.

I have recently had a set of Energiser Lithium AA cells in a camera. They
lasted *far* longer than 'ordinary' alkalines which I usually use. Maybe
they are sufficiently good to be worth paying their hefty premium? But I
do wonder how much is simply loss of voltage rather than actual energy
content.

You should be using NiMh rechargeable in most cameras.
The cameras have high discharge currents and alkalines can't keep it up.

You need to put new batteries in your reading glasses. He said
"Lithium".

The problem in cameras is the high peak currents that can be required.
These can no longer be satisfied without excessive voltage drop as the
batteries discharge. A neat solution (which has been proposed if not
actually implemented by some manufacturers) is to use an intermediate
supercapacitor that can be charged at a lower average current and thus
get longer battery life. Much the same principle as charging a
capacitor to power the flash.

MBQ

On 12 Dec, 07:18, wrote:

There was a supposed perpetual machine that did. It used 2 battery
piles disguised as just supporting pillars to electrostatically
attract a clock pendulum, and this slight force was enough to keep the
clock running.

"Hidden batteries" is one of the 4 classes of perpetual motion
machine, (really works, doesn't even start to work, deceitful hidden
power source, natural power source like an Atmos clock). However the
electrostatic pendulum is a fairly well-known bit of honest physics
demonstration kit (Glasgow University has one in an entrance hall?)
but I don't think they've been "passed off" like this.