In this paper, a new compact but efficient Maximum Power Point Tracking (MPPT) circuit is added to the conventional battery charger. The battery charging is composed of two steps of the Constant Current (CC) charging and Constant Voltage (CV) charging. Unlike the conventional CC charging, the new MPPT circuit can adjust the charging current according to the sunlight intensity to deliver the largest available solar energy to the battery. For the CV, the proposed battery charger can keep its charging voltage on the full charge level thus it does not lose the battery capacity due to the undercharging. The new battery charger can deliver more power to the battery than the charger without MPPT by 98.8%. Also, the charging time can be shortened by 52.3% with 10.5% of layout overhead.