I wanted to know that how do you know when the battery is going to run out when flying an airplane.i know that there are battery voltage meters but how do they work? If you keep flying till the battery runs out then will the battery malfunction?
You will normally feel when the power starts to decrease - then it is time to land.
When you have learned how long time you can fly on a battery then you can program the timer in the transmitter go give you an alarm some time before it is time to land so that you will be safe to have enough power to land.
The power to the motor will stop long before the power to the radio so you will be able to land your plane safely if you are flying with some height.
The battery will not be damaged if you start with a charged battery and land when the motor controller starts to decrease the power to the motor. Never try to drain the battery any more after landing or start with a non charged battery as the controller may se the battery as one cell less and fail to protect the battery.