A battery assembly comprising: a first lithium ion cell that includes a positive terminal, that includes a negative terminal, and that includes an electrically conductive can housing that encloses the first lithium ion cell and that: includes a top surface and a bottom surface; and includes first, second, third, and fourth side surfaces (136, 140, 144, 148) that are perpendicular to the top and bottom surfaces (116, 120), the first and second side surfaces (136, 140) arranged opposite one another, wherein the positive and negative terminals extend from the top surface of the can housing; a cell isolator constructed of two or more individual isolator pieces, which include a first piece and a second piece, wherein the first piece: is made of an electrically non-conductive material; includes a first wall member that completely covers and directly contacts the first side surface; includes a second wall member that is perpendicular to the first wall member and that directly contacts a first area of the third side surface; and includes a third wall member that is perpendicular to the first wall member and that directly contacts a first area of the fourth side surface; wherein the second piece: is made of the electrically non-conductive material; includes a fourth wall member that completely covers and directly contacts the second side surface; includes a fifth wall member that is perpendicular to the fourth wall member and that directly contacts a portion of the second wall member; and includes a sixth wall member that is perpendicular to the fourth wall member and that directly contacts a portion of the third wall member, wherein an inner surface of the first piece of the cell isolator is fixed directly to an outer surface of the can housing of the first lithium ion cell by an adhesive, and wherein the first piece and/or the second piece is formed with a bottom member that abuts the bottom surface. a first lithium ion cell that includes a positive terminal, that includes a negative terminal, and that includes an electrically conductive can housing that encloses the first lithium ion cell and that: includes a top surface and a bottom surface; and includes first, second, third, and fourth side surfaces (136, 140, 144, 148) that are perpendicular to the top and bottom surfaces (116, 120), the first and second side surfaces (136, 140) arranged opposite one another, wherein the positive and negative terminals extend from the top surface of the can housing; includes a top surface and a bottom surface; and includes first, second, third, and fourth side surfaces (136, 140, 144, 148) that are perpendicular to the top and bottom surfaces (116, 120), the first and second side surfaces (136, 140) arranged opposite one another, wherein the positive and negative terminals extend from the top surface of the can housing; a cell isolator constructed of two or more individual isolator pieces, which include a first piece and a second piece, wherein the first piece: is made of an electrically non-conductive material; includes a first wall member that completely covers and directly contacts the first side surface; includes a second wall member that is perpendicular to the first wall member and that directly contacts a first area of the third side surface; and includes a third wall member that is perpendicular to the first wall member and that directly contacts a first area of the fourth side surface; is made of an electrically non-conductive material; includes a first wall member that completely covers and directly contacts the first side surface; includes a second wall member that is perpendicular to the first wall member and that directly contacts a first area of the third side surface; and includes a third wall member that is perpendicular to the first wall member and that directly contacts a first area of the fourth side surface; wherein the second piece: is made of the electrically non-conductive material; includes a fourth wall member that completely covers and directly contacts the second side surface; includes a fifth wall member that is perpendicular to the fourth wall member and that directly contacts a portion of the second wall member; and includes a sixth wall member that is perpendicular to the fourth wall member and that directly contacts a portion of the third wall member, is made of the electrically non-conductive material; includes a fourth wall member that completely covers and directly contacts the second side surface; includes a fifth wall member that is perpendicular to the fourth wall member and that directly contacts a portion of the second wall member; and includes a sixth wall member that is perpendicular to the fourth wall member and that directly contacts a portion of the third wall member, wherein an inner surface of the first piece of the cell isolator is fixed directly to an outer surface of the can housing of the first lithium ion cell by an adhesive, and wherein the first piece and/or the second piece is formed with a bottom member that abuts the bottom surface.