I am discussing my experience with power bank actually power bank is a external device for our mobile phones when your mobile phone battery will discharge than where using power bank for change the battery this device is very useful for our mobile when we will on journey then suddenly discharge our mobile then power bank is very useful
I am telling you something about power bank.
How to make power bank on road and at home?
First you will buy one IC 7805 means 5 volt.
Second you will buy one battery of 9 volt and one resistant of 100 ohm
Its all connect to parallely then it will work properly.