Why going for a costly Power Bank to charge Mobile Phone? Just use a 9V battery and a few components to make a Portable Mobile charger. Its cost is just Rs.25 and if you use a Rechargeable 9V battery, it can be used up to three years. The Mobile phone battery is a high efficient long lasting Lithium Ion battery that has thousands of charge / discharge cycles. It requires 4 -6 volt DC for charging and the charging current can be between 200- 400 mA. We can drop the 9V from the battery to 6 volt using a Voltage regulator. That’s all. Make it and enjoy the satisfaction of a project building.
You need the following components
1. IC 7806
3. 9V Battery
4. USB Socket
IC 7806 is the Voltage regulator that gives 5.8 fixed output voltage. Even though it is 6V rated, around 0 .2 V drop occurs in its output. So we get 5.8 Volt for charging the Mobile battery. An LED can be included at the output to confirm the working on the charger. LED drops around 1.8V, so we get 4 Volt for charging. It is sufficient to charge the 3.6 or 3.7 V Mobile battery.
First identify the + and – pins of the USB socket. These will be at the ends. Remove the middle Data + and Data- pins. You can check the pins using a USB cable connected to a power source. Then mark + and – pins for easy connections.
Connect the Red wire of Battery Snap to the input pin ( First pin ) of IC 7806 and Black wire to the Ground pin ( Second pin ).Now connect the Output pin ( Third pin ) of 7806 to the + pin of USB socket. Connect the – pin of USB socket to the Ground pin of 7806.
Now solder 1K resistor to the Anode of LED and connect the free end of resistor to the + pin of USB socket and Cathode of LED to the – pin of USB socket.
Now the Portable Mobile charger is ready. Connect Mobile phone using USB cable. Phone will charge.
9V Battery is rated 500 mA and since the Mobile phone takes high current, you can charge maximum 2 times with a 9V battery, if the Mobile battery is fully discharged. Improvise the Charger using 9V rechargeable battery and a socket for its external charging. Then you can charge the battery using a 12V, 500 mA adapter. In this case, it will be a good Power bank for charging all USB devices and the battery lasts for more than 3 years.