A power management system for a vehicle includes a first battery monitoring module configured to monitor a first state of charge (SOC) of a first battery of the vehicle. The first battery has a first nominal voltage. A second battery monitoring module is configured to monitor a second SOC of a second battery of the vehicle. The second battery has a second nominal voltage that is greater than the first nominal voltage. A control module is configured to, using a direct current (DC) to DC converter, selectively charge the second battery with power from the first battery until the second SOC of the second battery is greater than or equal to a predetermined SOC.