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Author Topic: Arduino Uno to Monitor Voltage for 9v  (Read 365 times)
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I am currently finishing up my project and a perk I would like to have on it is a battery level indicator.  This would just be displayed on my TFT that I am using.  I found one schematic of a fella that was doing pretty much the same thing, but he was monitoring cell voltage on a LiPo.  Each cell had a voltage of 4.2v.  I am using a 9v battery that would be going to an analog input.  Am I correct in believing that 9v is way too high to for an analog in?  Does the onboard Arduino voltage regulator also work for analog inputs or is that just for the DC connector, or would I need to incorporate my own?  Thanks for the help, it's much appreciated!

- GSTEC
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Am I correct in believing that 9v is way too high to for an analog in?
Yes.  The maximum input is slightly above VCC.  Most Arduino boards VCC is 5V.  In the case of the Analog Inputs, anything above AREF (which is typically the same as VCC) will read as 1023.

  Does the onboard Arduino voltage regulator also work for analog inputs or is that just for the DC connector
Voltage regulators are for powering devices and have nothing to do with inputs.  It wouldn't make sense to put a voltage you want to monitor into a voltage regulator.  Because you would always get the same voltage "out".

You need a voltage divider.
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