There will be apps running in the background. Go to settings and in the option Battery and Device care you can shut the running apps and also sort out the memory and storage. Hope it comes right. Also don't leave the phone on charging whole night. In this country we have lot of power surges. Also avoid charging it on the car. Do it unless you have run out of charge completely. I have noticed quite a few phones over a period of time started to lose power faster from car charging.
