There was a problem with the IFI code 2 years ago which caused the battery voltage to show 8.2 or 8.3 volts. It required new libraries and a new linker file. You can read about it here:
http://ifirobotics.com/docs/memory_problem_8722.pdf
I have no idea if easyC implemented those changes or not.
You will also see wierd things if the battery is low and the backup battery is not attached.