Is it possible to create a voltmeter to test car batteries with an arduino and 3 leds?
I am trying to figure out how to wire an arduino as a voltage meter to test the voltage on car batteries and lead acid batteries in other things. I want to output the readings in 3 different colors leds (green, yellow, red) that correspond to the voltage range. Im a n00b in this field and Id hate to fry any components trying to figure this out without guidance, my main concern is making the voltage and current safe for the arduino, so I need to know any additional components necessary to make this work. I know I need to implement a voltage divider, etc to bring the voltage to a range the arduino can handle but do not know if the 1/4w resistors I have on hand will suffice. Id appreciate any feedback on how to hook this up and even more so anyone able to provide sample code and/or urls with hints to get this working.