Battery state estimation

This document describes techniques and systems that enable battery state estimation. The techniques and systems may be used to determine a shut-down voltage for a battery of an electronic device. Additionally or alternatively, the techniques and systems may be used to determine a state-of-charge of the battery, which may be determined relative to the shut-down voltage. The techniques and systems use current or expected conditions at the battery to estimate the battery state. These techniques can allow the electronic device to dynamically set a shut-down voltage, rather than using a fixed shut-down voltage over the life of the electronic device. The dynamically set shut-down voltage can provide a low margin, and therefore a greater portion of battery capacity, when operating in good conditions and provide a relatively large margin that is sufficient for poor conditions.