System and method for charging a plug-in electric vehicle

A method for charging a plug-in electric vehicle, comprising the steps of:

• (a) sensing a plurality of conditions pertaining to an external power source, a battery charger, and/or a battery unit, wherein at least one of the plurality of conditions is a droop voltage that generally represents the difference between an unloaded voltage of the external power source and a loaded voltage of the external power source, wherein the unloaded voltage is measured when the external power source is in an unloaded state and there is little or no current being drawn from the external power source by the battery charger, and the loaded voltage is measured when the external power source is in a loaded state and there is some current being drawn from the external power source by the battery charger;
• (b) evaluating each of the sensed conditions with a particular battery charging constraint;
• (c) reviewing each of the evaluations and identifying the most-restrictive constraint, wherein the most-restrictive constraint is the one that requests the least amount of current from the battery charger;
• and
• (d) operating the battery charger so that it does not violate the most-restrictive constraint.

A system for charging a plug-in electric vehicle, comprising:

• a battery charger being located on the plug-in electric vehicle and having an input coupled to an external power source, an output coupled to a battery unit, and one or more sensor(s) for monitoring external power source conditions and/or battery charger conditions;
• a battery unit being located on the plug-in electric vehicle and having an input coupled to the battery charger and one or sensor(s) for monitoring battery conditions;
• and
• a battery charging control module being located on the plug-in electric vehicle and being coupled to both the battery charger and the battery unit, wherein the battery charging control module receives readings from the battery charger sensor(s) and the battery sensor(s) and uses those readings to control the output power that the battery charger provides the battery unit, and one of the readings that is used in the control of the output power is an unloaded voltage reading for the external power source which is representative of the external power source when it is in an unloaded state and there is little or no current being drawn from the external power source by the battery charger.