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Q & A: Batteries in series

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Most recent answer: 10/22/2007
Q:
How do I determine the amperage of three AA batteries in series?
- tom mark
Birmingham, mi, usa
A:
It's easy to determine the net voltage of a series connected set of batteries;  it's simply the sum of the individual battery elements.  Three AA batteries in series yield about 4.5 Volts.   The net amperage is not so easy to determine.   The reason is that there is an internal restance associated with a battery that depends on several factors:  temperature, external load, age effects, etc.    Neglecting internal resistance, the net amperage is I = Vnet/Rext  where Vnet = 4.5 Volts and Rext is the external resistance, neglecting the internal resistance.  Adding in the internal resistance you get  I = Vnet /(Rext + Rint) .   Typical values of  Rint are several tenths of Ohms.

LeeH

(published on 10/22/2007)

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