I want to download a program to the Arduino and then disconnect the USB cable.
I guess I need to supply it with power from the other power connector. (Anybody got a pointer to the Power supply specs for the Mega 2560?)
My 'newbie' question is, does the program need to be re downloaded if the arduino is rebooted?
Input voltage specs are here: http://arduino.cc/en/Main/ArduinoBoardMega2560
The program is written to non-volatile flash memory, it persists even if power is removed.
Alternatively, if there is power where you need the arduino, just find a wallwart that has a USB socket on it - e.g. the chargers for iPhone or Kindle etc.
This otta do'er!
It would work, but those little PP3 batteries have very low charge and current capacity and are relatively expensive for what you get. Additionally, the voltage is higher than optimal for an Arduino so much of that precious energy is simply converted to heat in the voltage regulator. A pack of AAA or AA cells gives significantly more current and charge capacity.