This SAE Recommended Practice establishes the minimum interface compatibility requirements for electric vehicle (EV) inductively coupled charging for North America. This part of the specification is applicable to manually connected inductive charging for Levels 1 and 2 power transfer. Requirements for Level 3 compatibility are contained in Appendix B. Recommended software interface messaging requirements are contained in Appendix A. This type of inductively coupled charging is generally intended for transferring power at frequencies significantly higher than power line frequencies. This part of the specification is not applicable to inductive coupling schemes that employ automatic connection methods or that are intended for transferring power at power line frequencies. in the charge coupler). The charge controller signals the charger to stop charging when it determines that the batteries are completely charged or a fault is detected during the charging process. The following steps correspond with the diagram in Figure 1, and describe the closed-loop charging system. Vehicle charge controller determines desired current into batteries. ** Vehicle charge controller transmits charger output power request to charger via an IR communications interface. ** Charger controls input current from utility based on charger output power request from vehicle charge controller. ** Charger converts 60 Hz utility power to HFAC power. HFAC power is magnetically coupled from the coupler (primary) to the vehicle inlet (secondary). HFAC power is rectified/filtered to DC to charge the vehicle batteries. Process repeats until the vehicle charge controller determines the batteries are fully charged. ** Items with ** indicate control loop. ÑTypical closed-loop charging system.