I would like to connect a 15w 4.5v 1700mA solar array to an analog pin so I may log solar data. I assume 1700mA will fry the board and will need to use a resistor. Will this work without having common ground? And without frying the board?
Thanks!
You're measuring voltage - the current is what the panel is capable of supplying.
What you need to make sure of is that the output voltage never exceeds the AVR's supply voltage.
The analog input pin is a hign impedenace input and will not be damaged by the solar array, it will draw almost no current from the array. However you do need to be sure that the solar array can't ever go higher then +5vdc or you could damage the analog input pin.
The current that any power supply (including solar arrays) depends on the load it is wired too. Just because your array has a certain maximum current capacity doesn't determine how much current will be drawn by a specific load. Study up on Ohm's law and you will better understand the relationship of volts, amps and resistance.
Lefty
Ok, if I use a 10ohm resistor that would drop the amperage to 170mA and voltage to .45v. Other than the fact that I am only taking advantage of 1/10 of the arduino's 0-5v sensing window this should work right?
Ok, if I use a 10ohm resistor that would drop the amperage to 170mA and voltage to .45v
Why on earth do you want to limit the supply capability of what is probably quite an expensive panel?
Its not that I want to limit the supply of the panel, I just don't want to fry the arduino with 1700mA. I am using the arduino and processing to log solar data for my thesis project.
You won't fry the Arduino.
Read what lefty wrote.
Ok, thanks guys!