  This paper proposes a new equivalent circuit model for rechargeable batteries
by modifying a double-capacitor model proposed in [1]. It is known that the
original model can address the rate capacity effect and energy recovery effect
inherent to batteries better than other models. However, it is a purely linear
model and includes no representation of a battery's nonlinear phenomena. Hence,
this work transforms the original model by introducing a
nonlinear-mapping-based voltage source and a serial RC circuit. The
modification is justified by an analogy with the single-particle model. Two
parameter estimation approaches, termed 1.0 and 2.0, are designed for the new
model to deal with the scenarios of constant-current and variable-current
charging/discharging, respectively. In particular, the 2.0 approach proposes
the notion of Wiener system identification based on maximum a posteriori
estimation, which allows all the parameters to be estimated in one shot while
overcoming the nonconvexity or local minima issue to obtain physically
reasonable estimates. An extensive experimental evaluation shows that the
proposed model offers excellent accuracy and predictive capability. A
comparison against the Rint and Thevenin models further points to its
superiority. With high fidelity and low mathematical complexity, this model is
beneficial for various real-time battery management applications.
