Joe said:

Is there a way to measure the series resistance of a battery, or battery

pack? I am using LTSPICE to try and duplicate the results of a breadboard I

have constructed, but I have no idea what the series resistance of a battery

is. Maybe there's a ball park figure I can use? OR an equation?

TIA,

Joe

Measure the battery's voltage without any load. Call this value V1. Connect

an external load resistor across the battery and measure the battery's new

voltage and the current flowing through the load. Call these values V2 and

I. The battery's internal resistance is given by:

Ri = (V1 - V2) / I

Make sure you use a resistor that generates enough current to cause a

significant drop in the battery's voltage.

This assumes a battery model consisting of an ideal voltage source and a

resistor. For a more accurate measurement you'll need to plot a graph of

battery voltage vs. load current and evaluate the slope of the graph at the

operating point you need.

cheers,

Costas

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