Almost every fire prevention officer and each firefighter knows metal fires from demonstration tests as part of his training: gleaming bright light, high temperatures and spectacular reactions with water stay memorable to everyone present in these experiments. Everyone learns, that light metal fires practically can not be extinguished with water. On the contrary, the reaction with water induces a significant spread of fire. It is therefore understandable that fire safety officers are insecure when lithium based energy storage devices are used in companies. From this perspective, the author of the contribution under consideration report on the dangerousness of energy storage devices in the event of a fire.