Data and code for: Usable battery energy decline of a plug-in hybrid from owner-accessible charging records: an affine energy–SOC estimator

Supplementary data and code for the article "Usable battery energy decline of a plug-in hybrid from owner-accessible charging records: an affine energy–SOC estimator" (G. Husi, University of Debrecen, Faculty of Engineering; submitted to Journal of Energy Storage). The record contains anonymised per-session tables of 892 AC charging sessions of one BMW 225xe plug-in hybrid (2021–2026) derived from the manufacturer's owner data export, the MATLAB and Python code that reproduces the reported estimates and figures, and the code documenting the data preparation. Identifiers (VIN, addresses, coordinates) were removed and timestamps rounded to the hour; this does not change any reported estimate. See README.md for details.