Pocket Mobile Charger. Start Up Project 20

6ANo wonder, technology is that much advanced. You can charge your Mobile phone from a single Pen cell or even from a watch battery. The Mobile battery needs 5V for charging and the Pen cell has only 1.5 volt. How it is possible? There comes the help of DC-DC Booster Module with USB. It converts a voltage as low as 0.9V (900 mV) to 5.1 Volt. Its input voltage can be between 0.9V to 5V so it provides 5.1-5.2 V out put through the USB socket. So you can connect any USB device that requires 5V. Irrespective of the low input voltage, the output remains constant as 5.1V. The Module that works on 1.5V AA cell provides 200 mA current while two AA cells give 600 mA current. Let us build one Pocket Mobile charger. It is too small and costs only Rs.100

Specification of the Module

0.9V-5V to 5V 600mA DC-DC Converter Step Up Boost Module with USB

Input voltage :0.9-5V
Output voltage :5.1-5 .2 V
Output Current: 200 mA / 600mA (Single AA cell / Double AA Cells)
Switching frequency: 500 KHz
Voltage indication: LED lights with a load
Short circuit protection: No
Input Reverse Polarity Protection: No
Input voltage can be from
1.Solar panels
2. Generators
3. Batteries
4. Peltier elements

You need the following

1. DC-DC Booster Module with USB
2. Pen cell holder
3. AA Cell
4. Some wire
The Module can be directly connected to a Battery holder. Module has + and – points for soldering the wires. Connect the battery holder to the Module with correct polarity.


Let us check its performance and output voltage. Yes, it is giving 5.1v from 1.5V Pen cell
Insert the AA Cell in the holder. Connect the Mobile charger cable to the USB Socket of the Module. That all. Mobile will charge as usual.
Normal Zinc – Carbon AA Cell has the capacity of 400- 1700 mAh under 50 mA constant drain. So a single cell can be used for the emergency charging. It will not fully charge a flat battery, since most of the Mobile battery is rated more than 2800 mAh. In this case, you have to use two or three batteries. If you select Rechargeable AA battery, it can be charged again and again for the use.

Points to remember


  1. The Module has no Short circuit protection and Input polarity protection. So connect to the battery with correct polarity. You can add one IN 4148 diode from the battery + to the + terminal of module to prevent damage if there is an accidental polarity reversal. The Cathode of diode should go to the Module +.
  2. Input voltage should be between 0.9V to 5V to get 5.1- 5.2 V output. If the input voltage is higher than 5V, the Module will not work.
  3. LED in the Module lights when it gets 0.9 – 5V DC indicating the output voltage.


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