Solar charging of multiple battery banks

A switching device comprising:

• an interface to a plurality of power sources;
• a storage element for receiving and storing the power from the power sources;
• a connection to an auxiliary load;
• control logic for determining which of the plurality of power sources to invoke for powering the auxiliary load by identifying which of the primary sources has the highest potential for excess capacity, the control logic prioritizing the determined power source based on the potential for powering the auxiliary load without compromising a higher priority load, the primary load connected to at least one of the power sources;
• and
• a switch responsive to the control logic for connecting the determined power source to the auxiliary load by switching the auxiliary load to receiving the capacity from the primary source with the highest potential.

In a class 8 tractor trailer power management system, a method for directing excess solar and vehicular charge capacity to an auxiliary load, comprising:

• measuring available charge capacity from a reefer power system including a reefer battery, solar panel and charge controller for moderating solar power to the reefer battery;
• measuring available charge capacity from a cab vehicle power system including a propulsion system battery and alternator;
• determining, at a selector configured for switching charge capacity to the auxiliary load, which of the reefer power system and cab vehicle power system has the highest potential excess charge capacity;
• and
• directing the determined excess charge capacity to the auxiliary load while the measured available charge capacity remains sufficient for powering the respective reefer power system or cab vehicle power system by switching the auxiliary load to receive the charge capacity from either the reefer power system or the cab vehicle power system based on the determined highest potential.