Charge-depleting or EV mode refers to a mode of vehicle operation that is dependent on energy from the battery pack. Battery electric vehicles operate solely in this mode. Most plug-in hybrids operate in charge-depleting mode at startup, and switch to charge-sustaining mode after the battery has reached its minimum state of charge (SOC) threshold, exhausting the vehicle's all-electric range (AER). Although there is no technically mandated minimum all-electric range, future state and/or federal legislation may address this for policy purposes.