Maker Pro
Maker Pro

Capacities of C size NIMH batteries compared to AA.

M

Mauried

Jan 1, 1970
0
You now seem able to buy AA NIMH batteries with 2500 mAH capacities
but similar branded C size Nimh batteries have only 4500 mAH.
Given that the C battery is 4 times the volume of the AA something
seems wrong here.
Anyone seen NIMH C batterys with much more than 4500 mAH capacity.
 
D

David L. Jones

Jan 1, 1970
0
You now seem able to buy AA NIMH batteries with 2500 mAH capacities
but similar branded C size Nimh batteries have only 4500 mAH.

Interestingly, the best Energizer NiMH C cells are only 2500mAh rated,
same as their AA cells (@ 500mA CC discharge to 1V).
Compare the data sheets of both and the discharge curves are identical
up to and including 2C.
http://data.energizer.com/PDFs/nh15-2500.pdf
http://data.energizer.com/PDFs/nh35-2500.pdf
The only spec difference is internal resistance and impedance, which
are both lower in the C cell of course.
Given that the C battery is 4 times the volume of the AA something
seems wrong here.
Anyone seen NIMH C batterys with much more than 4500 mAH capacity.

Claim of 6000 here:
http://www.batteryjunction.com/tpeh-t6000.html
but no data sheet to back it up.

Dave.
 
P

Phil Allison

Jan 1, 1970
0
"Mauried"
You now seem able to buy AA NIMH batteries with 2500 mAH capacities
but similar branded C size Nimh batteries have only 4500 mAH.
Given that the C battery is 4 times the volume of the AA something
seems wrong here.


** Firstly - the volume ratio from AA to C is close to 3:1.

It would be rare to find a C cell with 3 times the capacity of the BEST
available AA of the same chemistry class.

So there is nothing " wrong ".

The explanation lies in market forces:

AA cells would have to be easily the highest selling size by FAR - as a
result it is also the part of the market where there is the fiercest
competition for top performance ( Eg - Duracell have been fighting
Energizer over it for decades with saturation TV marketing ).

No similar thing exists with C or D sizes - so cell makers have much less
motive to go to the same efforts with them.

Another example is with "sub C" size Ni-Cd cells that way outperform similar
C size cells - cos "sub C " is what the RC hobbies use.



...... Phil
 
O

Ooober

Jan 1, 1970
0
Phil Allison said:
"Phil Allison"

** Correction:






...... Phil


Is the SA of the electrode(s) more important than the volume - which is the
limiting or critical factor the electrolyte volume or the electrode(s) SA?
 
M

Mauried

Jan 1, 1970
0
Is the SA of the electrode(s) more important than the volume - which is the
limiting or critical factor the electrolyte volume or the electrode(s) SA?
The dimensions of the NIMH batteries that Jaycar sell which are the
ones Ive been comparing capacities of are

AA 13.5 mm by 50 mm
C 26 mm by 50 mm
Thats pretty close to 4:1 , not 3:1
 
M

Mik DaDik

Jan 1, 1970
0
Gday All,
AA 13.5 mm by 50 mm
C 26 mm by 50 mm
Thats pretty close to 4:1 , not 3:1

Ok Volume of a cylinder = Pi*r*r*l

So if L and Pi are the same the difference is r*r (of C size) / r*r (AA)
size

Therefore 13x13 / 6.75x6.75 = ratio of 3.71:1 or just under 4:1 ratio..

Sorry for the school stuff but it was 35 years ago since I did that so I
was interested if I still had it in me.


Cu

Mik
 
P

Phil Allison

Jan 1, 1970
0
"Mauried"
"Phil Allison"
The dimensions of the NIMH batteries that Jaycar sell which are the
ones Ive been comparing capacities of are

AA 13.5 mm by 50 mm
C 26 mm by 50 mm
Thats pretty close to 4:1 , not 3:1


** Several AAs I have here are 14mm x 48mm

Several C cells I have are 25mm x 47mm

Makes the ratio 1 : 3.1

Get a vernier gauge.

Then read the rest of my post - wanker.



...... Phil
 
Top