Here is a Power Bank for charging your Mobile phone while traveling or in the event of power failure. This power bank can deliver 4.5 Volts with reasonable current to charge the Mobile phone quickly. It can charge the Mobile phone 3-4 times . The Power bank uses a 4.5 V Rechargeable battery that can be charged using the Mobile phone charger or from the USB port.
4.5 V Rechargeable battery is now available with a rating of 1 Ah, 1.5 Ah, 2 Ah etc for less than Rs.100. This battery can be used or use a high efficiency Lithium battery.The Mobile phone battery is 3.6 V so 4.5 V from the Power bank is sufficient for charging. Transistor T1 act as a current regulator during charging the Mobile battery.
4.5 V Lithium Polymer Battery
Use suitable Sockets for connecting with the charger and Mobile phone.