I'm using this app called iCircuit for Android (I'm asking here because the iCurcuit forum has been forsaken) and when I have a circuit with a 3V battery and an LED, it lists the current as 2.15GA. I'm new to electronics so I'm wondering why its giving me this because I have connected an LED to a 3V battery before and its been fine.
The simulator is pretending that the battery is an ideal power source, i.e. no internal resistance. As such, it is using the largest possible value it can support, 2147483647A.
True power sources do have an internal resistance, and this is what is preventing the LED you put across it from burning out. LEDs should have a resistor placed in series with them so that you don't have to depend on this internal resistance.