Combined battery SOC/SOH estimation using a nonlinear adaptive observer

This work presents a modeling and estimation techniques for State of Charge and State of Health estimation for Li-ion batteries. The analysis is done using an adaptive estimation approach for joint state and parameter estimation and by simplifying an existing nonlinear model previously obtained from experiments tests. A switching mechanism between two observers, one for the charging phase and one for the discharging phase, is done to avoid transients due to the discontinuity of model´s parameters. Simulations on experimental data show that the approach is feasible and enhance the interest of the proposed estimation technique.