How To Make a Power Bank for mobile at Home?

When it comes to your particular need you can built any mAh of your choice.

First get a car charger

The charger that is used to charge phone from car, with car charger you can connect it with dry cell motor battery or any other battery.

How?

Open the car charger and after that look for the positive and negative contact. and then connect according to any battery that is up to at least 9 voltage and 12 voltage maximum. car battery is 12 voltage. This will charge your phone.

What battery can I used?

The list of battery are endless. as you can possibly used any battery. if the battery is not up to 9 voltage maybe 3.7 voltage then you will need 3 of it that's about 3.7 * 3 = 11.1 voltage. if the battery is 1.5 voltage then you will need 6 of it. 1.5 * 6 = 9 voltage. Another good battery is laptop battery. If you have any dead or not working laptop battery. or any you don't use anymore then you are good to go.

1. Crushed the laptop battery and open.
   
2. But first you have to check if the battery inside can still hold current very well If boost and then charged.
   
3. You will see about 6 small dry cell battery inside. every one of it is about 3 voltage.
4. But first you have to learn about voltage and mAh.

How to increase battery voltage?

example. if you have 3 battery of 3 voltage each and you need 9 voltage. you will have to connect the 3 battery positive to negative each. leaving the first battery positive and the last battery negative, and if you only need 3 voltage but want to increase the mAh the 3 battery will be connected with the three negative together and the three positive together, this will increase the mAhs * 3. Also you can used phone battery as well.