Help with understanding math for Internal resistance of battery...

S

stevwolf

Guest
I’m working though understanding this description in this book. see attachemnt.
I have tried this method for testing household batteries. I know there are other ways of testing batteries, but really I\'m just trying to work my way through this book as a personal exercise.
Please refer to my document I have have posted. The hand written notes are mine based on what things the terms mean. Hopefully I have them right.
Can you tell me If I am performing the example properly.
Here is the math using the equations in the document, step by step broken down based on the formula given in this book.
1. VL/RL = IL
2. VNL – VL = NewVL
3. NewVL/IL = RI

My test Example Using 1.5 Volt Battery (Good Battery)
Say I have an A Size 1.5 Volt A battery, the following are my results.
VNL 1.569
VL 1.548
RL R100 Ohm Resistor

1. VL/RL= IL 1.548 / R100 = 0.1548 (IL)
2. VNL-VL= (NewVL) 1.569-1.548= 0.021 (NewVL)
3. VLNew/IL=RI 0.021/.1.548=0.1356589147286822 (RI)

The final result and internal resistance is 0.13 Ohms.
However when I go to the following web site
https://www.translatorscafe.com/unit-converter/en-US/calculator/batt-internal-resistance/
And punch in the numbers I come to 1.357. Yes it’s the same number rounded up, but why is my number 0.13 and the web site moving the decimal place.1.3 Where am I wrong ?? They do seem to use a different math I think (This type of math is not my strong suit so Im not that clear on it.)
Who is right the web site my book or is my understanding / math wrong?


Here are the pages from the book that Im using. I hope they come through, I dont post many pictures and things. I have posted it in two ways, in case one does not work ??
thank you very much.

dyOeMjn.png


[Imgur](https://i.imgur.com/dyOeMjn.png)
 

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