An Intelligent NiCd and NiMH Battery Charger with Microcontroller

This paper presents the design and development of intelligent NiCd (Nickel-Cadmium) and NiMH (Nickel-Metal-Hydride) batteries charger with microcontroller. This intelligent battery charger can charge and discharge both NiCd and NiMH batteries with a board range of capacity. This design support fast charging on both NiCd and NiMH batteries and equipped itself with the reliability to protect the batteries from overcharging. The status and parameter of the batteries are displayed on LCD and the charger can directly connect to the normal 240VAC power point and make the charger very user friendly. This design is implemented using an 8-bit microcontroller which controls and monitors the charging operation of the charger. Constant current charging method is used as the charging algorithm of the charger. The charge termination method that implemented in the charger is Negative Delta Voltage method and follows by the trickle method to top up the batteries. For safety purpose, timer termination method is also included in the design. During experiment, the charging voltage increase as the charging time increase and the charging process was terminated as soon as the peak charge detected follow by the trickle charging. Moreover, discharging voltage decrease as the discharging time decrease and stop at the battery threshold voltage 3.2V.The experimental results show that the designed charger perform well and has a very good agreement with the features proposed.