Test Unit for Single Miniature Battery

Maheysh Sharrma

Abstract: In this paper we present a low cost electronic load which is suitable for measuring the discharge characteristic of a single miniature batteries in milli-ampere and sub milli-ampere. The discharge types include constant current, constant power, constant resistance and voltage-current relationship to see the voltage variation with discharging current. A charging circuit capable of charging at tickle charge to much higher capacity using constant current, constant voltage, CC-CV, pulse and brup charging is included in the circuit to observe effects charge-discharge cycles. The battery data acquisition system is assembled around 89S52 microcontroller with a 12-bit 4 channel differential input ADC, MCP 3304, and a DAC MCP 4921. The microcontroller based charging and discharging circuit is interfaced to a PC or a laptop using a USB to serial converter. The program for automation of electronic load is developed in Visual Basic. Measurement which includes open circuit voltage, load voltage and load current for different types of discharge and recharge are saved in excel format. Since the cost of the circuit is small and interfacing is through USB port, such circuits can be built in suitable number and can be used to test several batteries simultaneously.

Keywords: Battery, Charge, Discharge, Electronic Load, Battery Discharge, Microcontroller, USB Interfacing, Charge Discharge Cycle