 The study examined the effects of calendar aging on the open circuit voltage, OCV, state-of-charge, SOC, curve model parameters of lithium ion battery, lib, cells. The results showed that the OCVQ curve model parameters changed significantly with calendar aging. This indicates that calendar aging should be taken into account when using this type of model to estimate the SOC of lib cells. This article was authored by Simone Barcelona, Lorenzo Codcaza, Silvia Colnago, and others.