Answer :- Open an Emulator : 5554
Go to "C:\Program Files\Android\android-sdk\platform-tools>" and type a command : "telnet localhost 5554".
After then in same window telnet client starts. Type "help" command there.
"help" command gives you the list of all commands used by emulator. Type "help power" command there.
"help power" command gives you the list of all sub-commands used by "power" command. Type "power capacity 80" command there.
This will change your battery percentage of emulator. You can also give command like :
power capacity 40
power capacity 70
power capacity 10
power capacity 50
Battery percentage is reflected only on Emulator.