Battery unit

A battery unit comprising:

• positive electrode terminal means for connecting to an external device;
• negative electrode terminal means for connecting to the external device;
• first electric power storing means, connected to the positive and negative electrode terminals, for storing electric power;
• first current suppressing means, connected in series with the first electric power storing means, for suppressing rapid current changes with respect to the first electric power storing means;
• second electric power storing means, connected in parallel with the first electric power storing means, storing electric power;
• second current suppressing means, connected in series with the second electric power storing means, for suppressing rapid current changes with respect to the second electric power storing means;
• first switch means for selectively connecting and disconnecting a flow of electric current between the negative electrode terminal means and a negative electrode side of the first electric power storing means;
• second switch means for selectively connecting and disconnecting a flow of electric current between a positive electrode side of the first electric power storing means and a positive electrode side of the second electric power storing means;
• electrical bypass means for electrically connecting a point lying between the first electric power storing means and the first switch means to a point lying between the second electric power storing means and the second switch means;
• third switch means for selectively connecting and disconnecting a flow of electric current in the electrical bypass means;
• and
• controller means for controlling an on-off state of each of the first, second and third switch means.