## Introduction: Arduino Voltmeter (Cars Battery Measurement System)

Have you ever wanted a selfmade, opensource Voltmeter for your car ?

Please do not measure higher voltage than 12V!

With some low-cost electronic parts, you will build this in a few minutes!

Parts of this project: -> Arduino Uno or Duemilanove (available here: http://amzn.to/1CvVgqa )

-> LC Display (16x2) (available here: http://amzn.to/1IGM6rv )

-> Breadboard (available here: http://amzn.to/1a2vAqs )

-> Some jumpers ( available here: http://amzn.to/1FWjL2r )

-> A potentiometer 10k Ω ( available here: http://amzn.to/1CZLw8b )

-> 1x 10 kΩ resistor, 1x 14 kΩ resistor, 1x Z-Diode (5,1V)

-> Arduino IDE ( available here: http://arduino.cc/en/Main/Software )

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If you like this project, please vote for it! Just click on the orange vote button in the upper right hand corner and click vote! I would really appreciate it!

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## Step 1: Creating the Electrical Circuit:

First of all, we have to search for the LC Display - Datasheet on the Internet. In this case, I used this Display here:

http://bit.ly/1BSWHd9

---> Open now the Arduino IDE, click on "data", click on "samples" , click on "Liquid Crystal" and load the "Hello World" -Sketch.

Now you are able to create your electrical circuit...

After all you can prove your electrical circuit, load the "Hello World" - Sketch, the LCD should work now.

## Step 2: Modify the Existing Circuit:

Ok.. Lets go to an interesting part:

For example, if you would like to measure the voltage of your cars battery, take your arduino voltmeter:

Princip of the Circuit:

-> The measurecircuit exists of a simple voltage divider using two resistors ( 10kΩ, 14kΩ) and a Z-Diode (5,1V)

-> The Z-Diode protects the Arduino in case of overvoltage!

-> If we would like to measure the voltage up to 12V, we have to use simple maths calculation.

-> The maximum Voltage of the analog Port (A0) is 5V.

-> I made a small maths calculation. Have a look at this :D

You only have to modify the existing Circuit :D

If you created the circuit, load the following Arduino Code onto your Microcontroller.

-> Have fun with your new car battery measurement system :D