BI CVn – A spotted, overcontact, type-W eclipsing binary

•Period behavior is examined, sine fit of Qian et al. (2008) is refuted.•New RV results, and new VRI and BVRI light curves are presented.•New WD analyses of our data and also the data of Qian et al. (2008).•All three models effectively agree within error limits.•The spot moves from 2005 to 2013. Follow-up observations are suggested.

We present photometric and spectroscopic observations of the eclipsing binary system BI CVn. Wilson–Devinney analysis of its light and radial velocity curves showed that the system is a W-subtype overcontact W-UMa type binary. We computed the absolute physical parameters of the system based on a mass ratio spectroscopically determined in this study. Though the orbital period had changed somehow in the past, it has remained constant for a long time since March 1999, contradicting the previous interpretations suggesting a cyclic variation superimposed on a quadratic change.