State of health of partially discharged cells

A method may determine a remaining capacity of a cell that includes a lithium-alloying material in an electrode using a controller. The method includes receiving a temperature signal representing a temperature of a partially discharged cell and receiving a voltage signal representing a voltage of the partially discharged cell. The method further includes determining a time-dependent fade component and a cycle-dependent fade component of the cell. The time-dependent fade component of the cell is determined based on the temperature, the voltage, and an operating time of the cell. The cycle-dependent fade component of the cell is determined based on a depth of discharge of the partially discharged cell and cycle count data representing cycle-dependent fade from previous cycles of the cell. The method further includes determining a remaining capacity of the cell based on the time-dependent fade component, the cycle-dependent fade component, and a reference capacity of the cell.