ARDUINO UNO DIGITAL DISPLAY SYSTEM FOR AUTOMOBILE BATTERY VOLTAGE AND CURRENT MONITORING

Abstract

Automobile batteries require practical monitoring of voltage and current to support early identification of abnormal operating conditions. This study aimed to design and implement an Arduino Uno-based digital display system for monitoring a nominal 12 V automobile battery. The prototype integrates a resistor-divider voltage sensor, an ACS712-20A current sensor, an LM2596 DC-DC converter, a 16×2 I2C liquid-crystal display, and a buzzer. A Research and Development approach organized as an engineering design cycle was used, covering system design, prototype assembly, functional testing, and evaluation. Voltage readings were compared with a digital multimeter at five test points and produced a mean absolute percentage error of 0.38%. Current readings were examined under five charging and discharging conditions and produced a mean absolute percentage error of 3.61%; the largest relative deviation occurred at the lowest-magnitude discharge point. The buzzer remained off at 11.50 V and activated below 11.50 V, confirming the programmed comparator logic. The findings support the prototype as a simple continuous voltage-current and status monitoring device under the tested conditions. The study does not establish direct ampere-hour capacity or validated state-of-charge estimation; further validation with calibrated reference instruments, repeated measurements, multiple batteries, environmental variation, and dynamic automotive loads is required.