This has to happen with the mobiles that we currently have. We not only have a phone in our hands, but it is a device that has a music player, calendar, game player, a book lens and of course, a device with an Internet connection.
With all these resources, the battery is very limited, so the phone will require the use of more battery to make a call or to find the signal.
Word of warning when dealing with high powered batteries always be careful. get the advice of a good residential electrician, because its just not worth the risk play with this sort of power when you do not know what you are doing.
In this way, it is best to keep the phone charged above 10%. Then the phone can be in battery saving mode and how not to affect its performance.