Natural speed, please
According to reports, the lithium primary batteries were not declared as hazardous materials. If lithium primary batteries become internally shorted, due to their high amount of stored energy and chemistry, they can generate enough heat to ignite the internal lithium. Once ignited, the remaining batteries in a shipping carton or on a pallet will ignite. The lithium fire would then burn at a high enough temperature to burn through an aircraft’s aluminum fuselage. Further, most standard fire extinguishers or aircraft fire systems are useless against a lithium fire due to its high burning temperature.
Secondary batteries have a differing chemistry and are defined as being rechargeable. They are usually shipped from their manufacturer partially charged in an attempt to keep the energy density as low as possible during transportation. The DOT and UN regulations divide secondary batteries into two basic categories, which are defined by the level of energy density contained inside the individual cells or batteries. The batteries used inside cell phones, computers and power tools typically fall into the lower energy density category and have much fewer transportation limitations; hence why they are allowed to fly on commercial airliners with passengers.
The batteries used in a typical UPS must be capable of supplying the high current demand of the UPS for a sustained period of time. The period of time may be from a few minutes to several hours, depending on the application. For many decades, the lead-acid battery (Figure 2) has met this demand. Its capability to supply the high current demands of the UPS is very good. However, its energy density to weight ratio leaves a lot to be desired. High power UPS systems capable of providing several hours of battery backup can have lead-acid battery banks weighing tons. The energy density of a lead-acid battery ranges from 30 to 50 Watt/Hours per Kg, while it is 110 to 160 Watt/Hours per Kg for Li-Ion chemistry batteries. This represents a weight reduction of two to three times that of an equivalent lead-acid battery. This makes Li-Ion batteries viable for use in electric vehicles as well as UPS products.
Unfortunately, all shipments of UPS units containing high energy density Li-Ion batteries, battery banks or batteries packaged inside a UPS must be shipped as class 9 hazardous materials and cannot be shipped on commercial airliners. They must ship by ground cargo only. This becomes very impractical and drives the costs associated with the incorporation of lithium batteries up even further.
