First, if you put more than 5V into the Arduino, you can damage it.
Yup, figured someone would say this. I'm trying to work around damaging the Arduino.
Do you have any idea what kind of voltage you'tre getting out of the pot. If the "hot" terminal on the pot is powered to 24V, that's a problem.
An "idea" of what I'm getting out of the pot is 24v, or two 12v car batteries, which I need to somehow, using the pot., read off current/voltage/ect. using the arduino. I thought maybe there would be a way to read off only one 12v battery but that would be less ideal because I believe I would need another board to read the other battery.
You can use a voltage divider (2 resistors, something like a non-adjustable pot) to knock-down the voltage, but the total resistance needs to be about 10 times the resistance of the pot or the voltage divider will affect the voltage coming out of the pot.
A voltage divider would work as long as it won't affect what the arduino is reading.
OK... You just need a common ground (connect the two grounds togeher) and you can read voltage from a separate source.
Read voltage from a separate source?