Design and Fabrication of An Automatic Temperature Control Lithium-Ion Battery Charger

Abstract

This study presents the design and construction of an automatic lithium-ion battery charger that monitors the temperature of the lithium-ion battery during charging and sends a signal to the relay to cut off the power supply from the battery terminal if the battery temperature rises above 45°C which is the maximum allowable temperature for charging most lithium-ion batteries. This charger also has an auto-cut-off circuit that cut off the power supply from the battery terminals upon fully charged with LED indicators to indicate when the battery is charging and fully charged. The system comprises a 220/15V AC stepdown transformer, LM317T, ATMEGA 328P microcontroller, LM35, and a 16×2-bit liquid crystal display monitor. In order to ensure optimal performance of the circuit, the battery charger was used in charging the 12volt 14Ah lithium-ion battery, the battery was exposed to various degrees of temperature to simulate a rising battery temperature. Above 45°C the trip signal was triggered and the LCD monitor displayed a message which prompts the user to cool the battery temperature.