Lithium cells are at risk of thermal runaway due to deposition of lithium metal within the cell, which can be caused by overheating, overcharge, over-discharge, charging below 0 Celsius, or mechanical damage. The venting gas is a mixture of Hydrogen and CO2, and smaller amounts of CO, CH4, C2H4, and C2H6 due to high temperature reactions of the cell chemicals. Hydrogen ignites when it reaches sufficient temperature in the presence of oxygen, but that temperature is caused by the thermal runaway within the cell.
To meet EC regulations, the cells must have electronic protection against charging below 0 Celsius or too high a temperature, overcharging, and over-discharging. Cells in series must have cell balancing circuitry. Has anyone done a tear-down and verified that the EE power bars have this protection circuitry?