Cost Effective Solar Charge Controller for Lithium Io1 Battery Using 555 Timer IC

Abstract

In this work, an 8 Watt Photovoltaic (PV) panel was successfully used to charge Lithium Ion battery (LIR-18650, 3.7V) using a custom designed and constructed Pulse Width Modulated (PWM) solar charge controller. The PWM charge controller is based on NE555 IC configured in astable mode of a variable pulse width. The charge controller includes automatic cut-off to prevent battery overcharge, achieved using the reset pin of the timer IC. The design of the charge controller makes it versatile, and able to charge Lead acid batteries and Li-Ion type batteries alike. In this report, the various ways in which the charge controller can be re-tasked 
for charging different types of rechargeable batteries are also presented.