A motor drive system of a vehicle includes: an inverter that receives power from a power source via a bus, where the inverter is connected to a motor of the vehicle; a driver that drives the inverter; a filter that filters a current signal received from the bus to generate a filtered signal; and a control module that operates in an impedance determination mode. The impedance determination mode includes: based on the filtered signal, controlling the driver and the inverter to generate a pulsed signal applied to the power source; determining a current level and a voltage of the power source due to generation of the pulsed signal, and determining impedance based on the current level and the voltage. The control modules are configured to: determine a characterization parameter of the power source based on the impedance; and perform a control operation or a countermeasure based on the characterization parameter.