Lithium battery capacities (18650).

[Ian Field]

Having discovered that recycling bins in various shops are a good source of
lithium battery packs that can be put to various uses, I notice quite a
spread in claimed Ah capacities on the information labels.

The first aquisition was labelled "5.2Ah" - there weren't any parallel
combinations as it contained an uneven number of cells.

The next rescue was marked "4.2Ah", and contained 3 sets of parallel pairs -
so I assume the individual cell capacity is 2.1Ah.

The next was lowest yet at 2.0Ah.

This seems to be quite a spread for apparently identical cells, so I'm
wondering if I'm missing something?!

Thanks for any help.

 

[Phil Allison]

Ian Field wrote:

Having discovered that recycling bins in various shops are a good source of
lithium battery packs that can be put to various uses, I notice quite a
spread in claimed Ah capacities on the information labels.

The first aquisition was labelled "5.2Ah" - there weren't any parallel
combinations as it contained an uneven number of cells.

The next rescue was marked "4.2Ah", and contained 3 sets of parallel pairs -
so I assume the individual cell capacity is 2.1Ah.

The next was lowest yet at 2.0Ah.

This seems to be quite a spread for apparently identical cells, so I'm
wondering if I'm missing something?!

** Nope - there IS an enormous spread in the Ah capacities of Li-Ion cells. of the same physical size.

What also varies is the cell's internal impedance and maximum practical discharge rate.

18650 cells vary from 1.3Ah to over 5Ah and max discharge rates vary from several hours to a few minutes, for special RC hobby types.

Chemistries differ, electrolytes differ and construction methods differ AND the cell voltages differ - some are 3.3V and others 3.7V

There is a good Wiki on the topic.

The only thing you can be sure about is they all use Lithium.


..... Phil

 

[Tom]

On 12/21/2014 10:11 PM, Phil Allison wrote:

The only thing you can be sure about is they all use Lithium.


.... Phil
And sometimes the Chinese lie.

 

[default]

On Mon, 22 Dec 2014 16:22:21 -0500, Tom <tombiasi@optonline.net>
wrote:

On 12/21/2014 10:11 PM, Phil Allison wrote:


The only thing you can be sure about is they all use Lithium.


.... Phil
And sometimes the Chinese lie.


Really.

 

[Maynard A. Philbrook Jr.]

In article <54988b93$0$20029$c3e8da3$1cbc7475@news.astraweb.com>,
tombiasi@optonline.net says...

On 12/21/2014 10:11 PM, Phil Allison wrote:


The only thing you can be sure about is they all use Lithium.


.... Phil
And sometimes the Chinese lie.

Reminds me when I bought a brick of AA cells at a computer show
for 5 bucks.

If I had looked closer I would of know something was wrong due to the
lite weight of the cells and short lived life..

a quick look indicate "Duracell" the Copper top but, a closer look, me
and my far vision and no readers on that day, showed "Duraking" and they
lied about them being Alkaline of course, they were carbon zinc crap
cells in cardboard tube.

Jamie

 

[Ian Field]

"Phil Allison" <pallison49@gmail.com> wrote in message
news:998a1aba-a1f4-408a-bfcc-94a43e80a610@googlegroups.com...

Ian Field wrote:

Having discovered that recycling bins in various shops are a good source
of
lithium battery packs that can be put to various uses, I notice quite a
spread in claimed Ah capacities on the information labels.

The first aquisition was labelled "5.2Ah" - there weren't any parallel
combinations as it contained an uneven number of cells.

The next rescue was marked "4.2Ah", and contained 3 sets of parallel
pairs -
so I assume the individual cell capacity is 2.1Ah.

The next was lowest yet at 2.0Ah.

This seems to be quite a spread for apparently identical cells, so I'm
wondering if I'm missing something?!


** Nope - there IS an enormous spread in the Ah capacities of Li-Ion
cells. of the same physical size.

What also varies is the cell's internal impedance and maximum practical
discharge rate.

18650 cells vary from 1.3Ah to over 5Ah and max discharge rates vary from
several hours to a few minutes, for special RC hobby types.

Chemistries differ, electrolytes differ and construction methods differ
AND the cell voltages differ - some are 3.3V and others 3.7V

There is a good Wiki on the topic.

The only thing you can be sure about is they all use Lithium.

Thanks, knowing there's a lot to take in is at least a start.