The battery packs are shown in greater detail in FIG. 5. Cylindrical cells 22, for example Lithium-Ion (Li-Ion) cells, are encased in an insulating material 22a. In a practical embodiment, an intumescent material is employed to surround the cells and absorb heat through conduction. When exposed to high heat or flame, the intumescent material undergoes an endothermic reaction to further absorb heat through its chemical reaction. The insulated cells are electrically coupled to each other and to a circuit board containing control electronics. Metal straps or contacts 22m couple cells to each other and extend outwardly from the cell pack, and fold down for soldering to conductive (brass) pads 22n on the circuit boards. The circuit board comprises a first set of cell monitoring electronics 24c. The control electronics monitor cell status along with cell charging and cell balancing among other tasks. Data generated by the control electronics is communicated to the overall system controller by the CANbus diagnostics connector.