January 4, 2021
Why do lithium battery manufacturers require that lithium batteries only have 30% power when shipped by air?
At the 25th meeting of the ICAO Dangerous Goods Expert Committee on October 19-30, 2015, representatives from various parties discussed this issue enthusiastically. The sponsor pointed out that there is a greater danger in the transportation of lithium batteries. Still, When the battery charge SoC is reduced to a lower level, it can greatly reduce the lithium battery's thermal diffusion and the occurrence of dangerous accidents, which can effectively reduce the risk of air transportation.
Regarding the battery industry’s concern about the impact caused by the self-discharge of lithium batteries, it is a normal situation to claim that a discharge rate of 2% per month is a normal condition. Maintaining sufficient SoC to solve the need to store lithium batteries under long transportation times and too low SoC will directly lead to the battery's degradation, thereby damaging the battery.
Test results from multiple laboratories, including the FAA Technology Center, show that when the state of charge drops to 30%, most of the battery cells tested have no heat conduction diffusion phenomenon. For most battery cells today, 30% of SoC is a relatively safe capacity ratio.
After heated discussions, the expert group agreed to limit the SoC to 30%. This capacity level considers that most batteries have sufficient storage time and will not affect battery life due to self-discharge. The meeting decided to include this content in "Technical Instructions" TECHNICAL INSTRUCTIONS FOR THE SAFE TRANSPORT OF DANGEROUS GOODS BY AIR, 2015-2016 EDITION/ADDENDUM NO.3. It will be implemented from April 1, 2016.
However, some batteries are not suitable for the above regulations. For example, the supply chain is very long and needs to be used after reaching the destination. The expert committee agreed to set up a special rule to provide solutions for more than 30% of SoC batteries, thus adding the A331 clause;