Portable Embedded System for Accurate Assessment of Lithium-Ion Battery Capacity

Lithium-ion batteries have become a fundamental power source for a wide range of applications, and proper monitoring and control of these batteries is useful to ensure safe and efficient operation, avoid risks, and prolong their lifetime. Charging capacity testing is a crucial indicator of battery health and performance status, allowing to estimate battery autonomy and detect degradation mechanisms. This paper presents the design, implementation, and experimental results of a portable and low-cost electronic system called Core Phantom, developed to evaluate the charging capacity of lithiumion batteries. The system can assess batteries up to 60V and allows setting the discharge current up to 5A and the cut-off voltage for the capacity test. The Core Phantom system uses an ATMega328P microcontroller as the central control unit, a controlled charging circuit, a thermal dissipation module, and additional components such as a real-time clock, SD card storage, and an LCD for the user interface. The design includes protection measures to ensure safe operation within the specified thermal ranges. The experimental results show discharge tests performed on three commercial lithiumion batteries. The tests revealed significant discrepancies between the capacities reported by manufacturers and actual measurements, underlining the importance of performing rigorous evaluations before the design and implementation stages of lithiumion battery cells or banks.