Design and experimental setup of a backup battery as a source to mobile phone battery

The charging of a mobile with direct DC supply at low cost is becoming an innovative technology. A new approach to recharge the mobile battery by direct DC supply without the conversion of AC to DC is reported. The approach applies a three terminal voltage regulator 78M05 IC to give a constant voltage 5V and current ≈500mA from a 9V rechargeable battery connected parallel to the voltage regulator. It is observed that the voltage difference of the rechargeable battery drops when the mobile phone battery is charged and a voltage regulator is added in addition to regulate constant voltage finally. The analysis was also done by the AC power supply via the mobile charger. The charger is helpful for the charging of the mobile phone battery when there is no AC power supply. The entire setup can be reduced as an integrated chip along with the mobile phone charger, so the size of the charger remains same. Based on extensive simulation results using Matlab/Simulink and experimental results, it has been established that the performance of the controller both in transient as well as in steady state is quite satisfactory.