Internal battery heating comprising a parallel and a series arrangement

An internal battery heating system comprising:

• a core battery having a plurality of cells;
• a heating circuit electrically coupled to the core battery, the heating circuit comprising a plurality of electrochemical sub-cells each electrically coupled to the heating circuit via a pair of switches, such that the plurality of electrochemical sub-cells may be alternated between a parallel arrangement and a series arrangement, wherein a quantity of electrochemical sub-cells in the heating circuit is at least one greater than a quantity of cells of the core battery;
• and
• a controller adapted to provide coordinated switching of each of the pair of switches for each of the plurality of electrochemical sub-cells for alternating between the parallel arrangement and the series arrangement, such that the parallel arrangement provides the core battery with a higher voltage for discharging to the plurality of electrochemical sub-cells, and in the series arrangement, the greater quantity of electrochemical sub-cells in the heating circuit provides a higher voltage thereby discharging to the core battery for internally heating the core battery without the use of an electrical conversion device or an external power source.