The Power Regulator board has connections to three 12 volt batteries. Two batteries were for the two drive motors and one was for the electronics. The logic battery went to a switching power regulator that supplied regulated 5 volts DC and unregulated 12 volts DC. The board also has a 28 volt DC input from the external power station to recharge the batteries.
The schematics are available for free on the download page.
The power supply and battery charger board.