Lead-acid batteries are based on very old technology, but still provide the cheapest, non-volatile power storage for electronics. Lithium-based batteries offer the highest energy density of any commercially available battery, yet they are far more expensive relative to the power they store. In addition, Lithium-based batteries are typically far more volatile, risking chemical spills and fire if they are charged/discharged too quickly, if their temperature is too high or if they are punctured. For these reasons we do not recommend Lithium-based batteries unless space and weight is very limited. Since lithium-based batteries are used so rarely in the Motus network, they will not be discussed further here.