That's my first post here, looks like an awesome place with so much to learn!
I found something about how to measure the voltage between the 5V pin and a potentiometer, but I dont see how I apply the same logic to measuring the voltage of a super-capacitor that should be charged up to say ~2.5V.
I'm making a solar power management unit that charges super-capacitors to 2.5V and then disengages so they don't get over charged.
I think I'm going to use a transistor or a relay for that, still not sure, I could use some input about that one as well.
I'm still a noob about these amazing little things called Arduino and electronics.
I'm a mech. engineering student so I'm somewhat electrically impaired!
My last (most complicated) Arduino thingy was just a led traffic light that's controlled by a button.
Arduino can directly measure a voltage between 0 and 5volt with one of the analogue pins.
It's wise to use a 4k7 or 10k protection resistor between +cap and analogue input.
The A/D converter spits out numbers between 0-1023.
If you read the value of the analogue pin and display it on the serial monitor, then 2.5volt will give you a number of about 512.
You can use those values to switch a small 5volt reed relay with an output pin.
Tell us more, so we can advise you about the code.
Leo..
To determine if Mike is right (he usually is), just hook up a 5V source to an analog input with a 1K resistor for safety, disconnect the Arduno's power (but not common ground) and see if any current flows through the resistor. If it is practically zero, try a lower resistor, measure again and finally direct connection.
Assuming that's ok, no resistor needed on the analog input and you can measure the voltage.
I think it is a good idea to add a 10K resistor in series with an analog input, especially for beginners, who might accidentally apply more than 5V or negative voltages to an input.
The way this forum works is that you ask the question and get an answer, like you did.
If you don't understand the answer or don't feel it answers your question then you ask again being more specific as to what you didn't understand.
Have you read the "how to use this forum" sticky post at the top. It gives advice on asking good questions. They are ones that give the answer you are after.