How do I calculate a battery internal resistance?

R

royalmp2001

Jan 1, 1970
0
I am looking at various 9V rectangular batteries, notable Duracell.

If I know the capacity in mAH, can I calculate the internal resistance
somehow?
Thanks, guys.

G

Greg Neill

Jan 1, 1970
0
royalmp2001 said:
I am looking at various 9V rectangular batteries, notable Duracell.

If I know the capacity in mAH, can I calculate the internal resistance
somehow?
Thanks, guys.

You can measure it by observing the voltage drop when
say that the known load resistance is 100 Ohms, and

The internal resistance is then (9V - 8.85V)*(100 Ohms)/9V

Or you could go to the manufacturer's web site and look
for battery technical data sheets. For example, the
Duracell 9V spec sheet can be found at:

http://www.duracell.com/oem/productdata/default.asp

S

Slavek

Jan 1, 1970
0
Rule of thumb is ~0.2R per alkaline cell of new battery; so 9V it is
built from
6 cells that gives ~1.2 to 1.5R;
Measure the best ;
Datasheets from Duracell the next.;

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