Motorola Microcontroller Dedicated Battery Pack Smart Charging Instrument

The system of charging up a storage battery based on the MOTOROLA Micro Control Unit is introduced in this paper. The characters of the system are compared with the old charging system of the Ni-Cd storage battery that used traditional charging method. That has show the new design charging system has higher efficiency.The traditional normal method for charging up storage battery is the constant voltage or constant current charge. In the charging process 10 to 20 hours are used. For shortening the charge time, we must take charge current in that process to be controlled. According to the three law put forward by scientist named MARSE from the United States, which say the pulse charge, the pulse discharge can do away with the battery polarization phenomenon, decrease the pressure inside, temperature of the storage battery and the resistance inside, increase the speed of charging process. As to realizing the method, we need to adopt the circulating way of charge-discharge- charge. The quick charge system for realizing this kind of mode generally should include control circuit, charge circuit and discharge circuit. The control circuit is based on a 8 bi t MOTOROLA single chip microcomputer MC68HC705SR3 with 4MHz clock frequency, The Pulse-Width Modulation switching power supply is used in the charge circuit. When charge starting, the 8 bit timer in CPU will measure the lasting time, then produce a waveform, bring up a time interrupt which can be used in fixing a time (count down way) and discharge control, at the same time driving transistor do away with polarization of the battery by discharge. On the base of variance output voltage parameter to be checked-up in the process of charge several MSEL, On the model of A/D conversion MCU inside transform analog quantity to digital quantity, By the software system, the charge voltage is controlled properly through controlling PMW so as to guarantee a constant value of the pulse voltage (charge and discharge) and the width ratio of charge and discharge and get the higher charge efficiency.