Simultaneous Constant Current Discharge of Multiple Batteries

摘要

Constant current discharge test is a standard test applied on the battery to test its capacity. In constant current discharge mode the battery is discharged at constant load current till the battery terminal voltage falls to certain value which is a point where the battery has given up 80 to 95% of its stored energy. This paper describes a microcontroller based multiple battery constant current discharge unit which is useful to test up to four batteries simultaneously at same or different constant current. The system consists of a 12-bit data acquisition circuit based on 8-channel ADC, MCP 3304 and a DAC MCP 4921 driven by 89S52 microcontroller. The system is connected to computer through a USB-Serial converter. The GUI and the program is designed in visual basic where the user can enter the discharging parameters and observe the voltages of discharging batteries while the test proceeds. The setup is designed to handle batteries having terminal voltages up to 4 volts and discharge current up to 400mA. The range can be easily extended to accommodate higher voltage battery and discharge current. Several cells of commonly available size, make and chemistry were tested at constant current some of which are reported in the paper.