How Do You Calculate Battery Internal Resistance from Load Conditions?

AI Thread Summary
To calculate the internal resistance of a battery, the difference in terminal voltage under load conditions must be analyzed. The battery shows a terminal voltage of 25V without load and 24V with a 10A load, indicating a voltage drop of 1V due to internal resistance. Using Ohm's Law, the internal resistance can be determined by dividing the voltage drop (1V) by the load current (10A), resulting in an internal resistance of 0.1 ohms. The discussion emphasizes understanding the equivalent circuit of the battery and the impact of load on terminal voltage. This approach is essential for accurately assessing battery performance under different conditions.
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Homework Statement



I have been stuck on the following problem for 2 days now, can anyone help?

The p.d. at the terminals of a battery is 25V when no load is connected and 24V when a load taking 10A is connected. Determine the internal resistance of the battery...

Thanks



Homework Equations



The Attempt at a Solution

 
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In this diagram, (load present, but not shown) what is the voltage across the resistor?

What current is flowing in it?

So, what is the value of the resistor?

internal resist.PNG


This is the equivalent circuit of a battery. When there is no load, the voltage across the internal resistance is zero, so the voltage at the terminals is 25 volts. When there is 10 amps flowing, a voltage is dropped across the internal resistance, so the output is 24 volts.
These voltages are relative to the negative terminal.
 

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