(4) Obtain the impedance of the battery based on the following equations: 2 = Q' 1 V₁ = R₁C₁ V₁ = Vocu (2) + V₁ + R₂I. +1, -V₁ + It

is assumed that the OCV is linear with the battery SOC: Vacu (2) = az+3. Note that the sign convention of the current signal follows typical EIS testing, that is, a positive current denotes a charging event.