Characterizing Battery Behavior for Time-Dependent Currents

Batteries connected to the dc grid are exposed to a variety of currents. We explore in this paper the response of the battery to commonly seen current waveforms to understand the impact of the converter on the battery. At the frequencies considered, the battery's small-signal model is shown through impedance spectroscopy and ripple tests to be well represented by a pure resistor, and at dc currents over 2 C, Joule heating is shown to have a nonnegligible effect on the impedance. Furthermore, the amplitude of pulses that can be applied is shown to be governed by diffusion limits and the battery's state of charge.