Most of the mobile phone complaints are related to the power supply. This is mainly because of improper charging and use of non-recommended chargers and low-quality batteries. Depending upon the make and model, the charging time of mobile phones varies from 1 hour to 3 hours. The charging current is also different for different models. So it is better to use the charger specified by the company only. Equipment for measuring the capacity or the backup time of a battery are not readily available in the market. But by measuring the charging and discharging currents, the approximate backup time of a battery can be found out. For example, charge a battery of 4.8V, 400mA rating for 1 minute and check whether it can discharge for 1 minute through a 400mA torch bulb. If the battery is discharged fully, it would not get charged again through a normal charger. The battery would require an initial charge or boosting. Here’s a multipurpose circuit (see Fig. 1) for battery boosting as well as ...