Method and system for detecting power supply source electrical current capacity

An apparatus (530) and method for determining a power supply electrical current capacity. An operating circuit (564) is placed into an operating mode that causes the operating circuit (564) to have a determined electrical current consumption. A charging circuit (526) that is electrically connected in parallel with the operating circuit is configured to provide a maximum charging current to a power pack (518). After configuring the charging circuit (526), a value of a measured charging current provided to the power pack (518) is received. After receiving the value of the measured charging current, an electrical current supply capacity value of the external power supply (506) is determined as a function of the determined electrical current consumption and the value of the measured charging current.