As per the answer on Android StackExchange, one can change battery capacity within range [0,100]. But emulators runs in the host machine, so one can assume that the emulator is always charged unless the host machine runs out of battery/power source. Is the number 50 in 50% charging arbitrary?
On the other hand, I tried setting the battery capacity below 5%, but it didn't generate battery low notifications. When it was set to 0%, it didn't shut down like the real Android device. Is the battery icon redundant in emulators, just like the Easter Egg?