NOVELTY - A battery load leveling system comprises an ultracapacitor (140). A diode (142) coupled in series electrical circuit with ultracapacitor and poled to conduct current from ultracapacitor to the electric traction motor (106). The series electrical circuit coupled in parallel with the batteries so that the ultracapacitor provides current to the load when the battery terminal voltage is less than voltage on the ultracapacitor. A battery switching circuit (110) connects the batteries (102,104) in either a lower voltage parallel arrangement or a higher voltage series arrangement.    USE - For an electric or hybrid vehicle.    ADVANTAGE - Current limiting apparatus provides improved load leveling of the batteries by preventing high current recharge of ultracapacitor from the batteries and immediately after the system experiences high power pulse loads due to heavy current thaw in load such as would be occasioned by rapid vehicle acceleration where load comprises an AC or DC electric motor. The ultracapacitor is sized to provide sufficient power for initial acceleration and deceleration during stop and go urban driving and for short bursts of power during passing maneuvers. A relatively low cost ultracapacitor electronic interface allows decoupling of the battery from the ultracapacitor during specific periods and utilizes a higher percentage of the ultracapacitor ideal stored energy, during regenerative energy capture. This stored energy is used during future accelerations to save fuel and increase range. The system also allows for proper matching of the input voltage of the traction drive to efficiently operate for both low speed urban and high speed highway driving. The system facilitates a low cost ultracapacitor/battery interface apparatus that does not require a relatively expensive DC-DC converter. The system is robust, reliable, and provides a smooth transition between battery switching events. The solid state battery switching circuits, contactors (if used) do not have high transient current stress. The system control is based on simple voltage, motor speed feedback sensors, and/or torque command signals. The ultracapacitor interface provides an increased utilization of energy storage compared to known interface techniques. Low speed urban driving type cycles may be run primarily using the ultracapacitor that enhances battery life. High specific power ultracapacitor component exhibits high round-trip efficiency. The ultracapacitor is essentially on the DC link to facilitate eliminating DC-DC converter losses. The combination of ultracapacitor and a battery provide sufficient energy storage that may be utilized during long up-hill and down-hill grades for both low speed and high speed operation. The system also provides improved overall system round-trip efficiency, e.g. ultracapacitor, battery, and/or traction drive, especially during low motor speed operation when the DC link is operated at approximately 50 percent of rated voltage as compared to high-speed high-power operation.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for    (1) method of assembling a battery load system;    (2) electric vehicle;    (3) hybrid vehicle    DESCRIPTION OF DRAWING(S) - The drawing shows a battery load leveling system including an exemplary battery switching circuit.    Batteries (102,104)    Load (106)    Battery switching circuit (110)    Ultracapacitor (140)    Diode (142)