This study focuses on a series Li-ion battery electrical energy diagnosis and management system. A failure to protect batteries adequately can lead to shortened lifespan, reduced efficiency, and compromised accuracy in the state of charge (SOC). Using Li-ion batteries electric series energy diagnosis management controller can protect batteries from damage, and maintain working efficiency. The entire system consists of a battery diagnosis module and a module for the management of batteries. The system is capable of balancing the voltage for each battery, estimating residual energy, and determining the state of health of batteries. The controller comprises a single 8051 chip and IC-LTC6802 with the aim of protecting batteries.